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OPA615IDGSR

OPA615IDGSR

  • 厂商:

    BURR-BROWN(德州仪器)

  • 封装:

    TFSOP10

  • 描述:

    IC DC RESTORATION CIRCUIT 10MSOP

  • 数据手册
  • 价格&库存
OPA615IDGSR 数据手册
OPA615 www.ti.com...................................................................................................................................... SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009 Wide-Bandwidth, DC Restoration Circuit Check for Samples: OPA615 FEATURES DESCRIPTION • • The OPA615 is a complete subsystem for very fast and precise DC restoration, offset clamping, and low-frequency hum suppression of wideband amplifiers or buffers. Although it is designed to stabilize the performance of video signals, the circuit can also be used as a sample-and-hold amplifier, high-speed integrator, or peak detector for nanosecond pulses. The device features a wideband Operational Transconductance Amplifier (OTA) with a high-impedance cascode current source output and fast and precise sampling comparator that together set a new standard for high-speed applications. Both the OTA and the sampling comparator can be used as stand-alone circuits or combined to form a more complex signal processing stage. The self-biased, bipolar OTA can be viewed as an ideal voltage-controlled current source and is optimized for low input bias current. The sampling comparator has two identical high-impedance inputs and a current source output optimized for low output bias current and offset voltage; it can be controlled by a TTL-compatible switching stage within a few nanoseconds. The transconductance of the OTA and sampling comparator can be adjusted by an external resistor, allowing bandwidth, quiescent current, and gain trade-offs to be optimized. 1 2 • • • • • • PROPAGATION DELAY: 1.9ns BANDWIDTH: OTA: 710MHz Comparator: 730MHz LOW INPUT BIAS CURRENT: ±1μA SAMPLE-AND-HOLD SWITCHING TRANSIENTS: ±5mV SAMPLE-AND-HOLD FEEDTHROUGH REJECTION: 100dB CHARGE INJECTION: 40fC HOLD COMMAND DELAY TIME: 2.5ns TTL/CMOS HOLD CONTROL APPLICATIONS • • • • • • • • • BROADCAST/HDTV EQUIPMENT TELECOMMUNICATIONS EQUIPMENT HIGH-SPEED DATA ACQUISITION CAD MONITORS/CCD IMAGE PROCESSING NANOSECOND PULSE INTEGRATOR/PEAK DETECTOR PULSE CODE MODULATOR/DEMODULATOR COMPLETE VIDEO DC LEVEL RESTORATION SAMPLE-AND-HOLD AMPLIFIER SHC615 UPGRADE Ground 9 CHOLD 4 The OPA615 is available in both an surface-mount and an MSOP-10 package. Base 3 2 Hold Control 7 Switching Stage 10 S/H In− 11 Emitter OTA Sampling Comparator (SC) S/H In+ SO-14 12 SOTA ∞ Biasing Collector (IOUT) 1 IQ Adjust OPA615 13 +VCC 5 −VCC 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2004–2009, Texas Instruments Incorporated OPA615 SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009...................................................................................................................................... www.ti.com This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. Table 1. ORDERING INFORMATION (1) PRODUCT PACKAGE PACKAGE DESIGNATOR OPA615 SO-14 D OPA615 (1) MSOP-10 DGS SPECIFIED TEMPERATURE RANGE PACKAGE MARKING –40°C to +85°C OPA615ID –40°C to +85°C BJT ORDERING NUMBER TRANSPORT MEDIA, QUANTITY OPA615ID Rails, 50 OPA615IDR Tape and Reel, 2500 OPA615IDGST Tape and Reel, 250 OPA615IDGSR Tape and Reel, 2500 For the most current package and ordering information see the Package Option Addendum at the end of this document, or see the TI website at www.ti.com. ABSOLUTE MAXIMUM RATINGS (1) Supply Voltage ±6.5V Differential Input Voltage ±VS Common-Mode Input Voltage Range ±VS Hold Control Pin Voltage –VS to +VS Storage Temperature Range –65°C to +125°C Junction Temperature (TJ) +150°C ESD Ratings: Human Body Model (HBM) (2) 1000V Charge Device Model (CDM) 1000V Machine Model (MM) (1) (2) 2 150V Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not implied. Pin 2 for the SO-14 package and pin 1 for the MSOP-10 package > 500V HBM. Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 OPA615 www.ti.com...................................................................................................................................... SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009 BLOCK DIAGRAMS SO−14 MSOP−10 Ground 9 CHO LD Base 4 Ground 3 6 2 Hold Control 7 S/H In+ 10 S/H In− 11 12 SOTA ∞ 1 Biasing 3 2 1 Hold Control OTA Base Emitter Switching Stage Sampling Comparator (SC) CHO LD 5 Sampling Comparator (SC) Collector (IO UT ) IQ Adjust S/H In+ 7 S/H In− 8 Emitter Switching Stage 9 OTA SOTA ∞ Collector (IO U T ) Biasing OPA615 OPA615 13 5 10 −VC C +VCC 4 −VC C +VCC PIN CONFIGURATIONS Top View IQ Adjust 1 14 NC(1) Emitter, E 1 10 +VCC Emitter, E 2 13 +VCC Base, B 2 9 IOUT, Collector, C Base, B 3 12 IOUT, Collector, C CHOLD 3 8 S/H In− 11 S/H In− −VCC 4 7 S/H In+ Hold Control 5 6 Ground OPA615 CHOLD 4 −VCC 5 10 S/H In+ NC(1) 6 9 Ground Hold Control 7 8 NC(1) BJT MSOP−10 SO−14 NOTE: (1) No Connection. Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 3 OPA615 SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009...................................................................................................................................... www.ti.com ELECTRICAL CHARACTERISTICS: VS = ±5V RL = 100Ω, RQ = 300Ω, and RIN = 50Ω, unless otherwise noted. OPA615ID, OPA615IDGS TYP PARAMETER CONDITIONS AC PERFORMANCE (OTA) Small-Signal Bandwidth (B to E) +25°C MIN/MAX OVER TEMPERATURE +25°C (2) 0°C to 70°C (3) –40°C to +85°C (3) UNIT MIN/ MAX TEST LEVEL (1) See Figure 36b VO = 200mVPP, RL = 500Ω 710 MHz min C VO = 1.4VPP, RL = 500Ω 770 MHz min C VO = 2.8VPP, RL = 500Ω 230 MHz min C Large-Signal Bandwidth (B to E) VO = 5VPP, RL = 500Ω 200 MHz min C Small-Signal Bandwidth (B to C) G = +1, VO = 200mVPP, RL = 100Ω 440 MHz min C G = +1, VO = 1.4VPP, RL = 100Ω 475 MHz min C G = +1, VO = 2.8VPP, RL = 100Ω 230 MHz min C G = +1, VO = 5VPP, RL = 100Ω 230 MHz min C Rise-and-Fall Time (B to E) VO = 2VPP, RL = 500Ω 2 ns max C Rise-and-Fall Time (B to C) G = +1, VO = 2VPP, RL = 100Ω 2 ns max C Harmonic Distortion (B to E) RE = 100Ω 2nd-Harmonic VO = 1.4VPP, f = 30MHz –62 –50 –48 –47 dBc min B 3rd-Harmonic VO = 1.4VPP, f = 30MHz –47 –40 –35 –33 dBc min B Input Voltage Noise Base Input, f > 100kHz 4.6 6.2 6.9 7.4 nV/√Hz max B Input Current Noise Base Input, f > 100kHz 2.5 3.1 3.6 3.9 pA/√Hz max B Input Current Noise Emitter Input, f > 100kHz 21 23 25 27 pA/√Hz max B Large-Signal Bandwidth (B to C) DC PERFORMANCE (OTA) Transconductance (V-base to I-collector) See Figure 37b VB = ±5mVPP, RC = 0Ω, RE = 0Ω 72 65 63 58 mA/V min A B-Input Offset Voltage VB = 0V, RC = 0V, RE = 100Ω ±4 ±40 ±47 ±50 mV max A B-Input Offset Voltage Drift VB = 0V, RC = 0V, RE = 100Ω ±160 ±160 μV/°C max B B-Input Bias Current VB = 0V, RC = 0V, RE = 100Ω ±1.5 ±1.7 μA max A B-Input Bias Current Drift VB = 0V, RC = 0V, RE = 100Ω ±12 ±12 nA/°C max B ±120 ±135 μA min A ±200 ±250 nA/°C max B ±110 ±125 μA max A ±200 ±250 nA/°C max B ±3.1 ±3.0 E-Input Bias Current VB = 0V, VC = 0V E-Input Bias Current Drift VB = 0V, VC = 0V C-Output Bias Current VB = 0V, VC = 0V C-Output Bias Current VB = 0V, VC = 0V ±0.5 ±35 ±35 ±0.9 ±110 ±100 INPUT (OTA Base) See Figure 37b Input Voltage Range RE = 100Ω ±3.4 B-Input 7 || 1.5 ±VS to VIO at E-Input 54 49 47 46 Input Impedance OTA Power-Supply Rejection Ratio (–PSRR) ±3.2 V min B MΩ || pF typ C dB min A A OUTPUT (OTA Collector) See Figure 37b Output Voltage Compliance IE = 2mA ±3.5 ±3.4 ±3.4 ±3.4 V min Output Current VC = 0V ±20 ±18 ±17 ±17 mA min A Output Impedance VC = 0V 1.2 || 2 MΩ || pF typ C B COMPARATOR PERFORMANCE AC Performance Output Current Bandwidth IO < 4mAPP 730 520 480 400 MHz min IIO = ±2mAPP, RL = 50Ω at CHOLD 1.4 1.5 1.7 2 ns max B Control Propagation Delay Time Hold ≥ Track and Track ≥ Hold 2.5 ns typ C Signal Propagation Delay Time S/H In+ – S/H In– to CHOLD Current 1.9 C Input Differential Voltage Noise S/H In+ – S/H In– 6 Track-to-Hold Hold Mode, VIN = 1VPP, f < 20MHz Output Current Rise and Fall Time Charge Injection Feedthrough Rejection (1) (2) (3) 4 ns typ nV/√Hz max B 40 fC typ C 100 dB typ C 7.5 8 9 Test levels: (A) 100% tested at +25°C. Over temperature limits set by characterization and simulation. (B) Limits set by characterization and simulation. (C) Typical value only for information. Junction temperature = ambient for +25°C tested specifications. Junction temperature = ambient at low temperature limit; junction temperature = ambient +23°C at high temperature limit for over temperature specifications. Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 OPA615 www.ti.com...................................................................................................................................... SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009 ELECTRICAL CHARACTERISTICS: VS = ±5V (continued) RL = 100Ω, RQ = 300Ω, and RIN = 50Ω, unless otherwise noted. OPA615ID, OPA615IDGS TYP PARAMETER CONDITIONS +25°C MIN/MAX OVER TEMPERATURE +25°C (2) 0°C to 70°C (3) –40°C to +85°C (3) UNIT MIN/ MAX TEST LEVEL (1) A DC Performance Input Bias Current Output Offset Current Input Impedance Input Differential Voltage Range Input Common-Mode Voltage Range S/H In+ = S/H In– = 0V ±1 ±3 ±3.5 ±4.0 μA max S/H In+ = S/H In– = 0V, Track Mode ±10 ±50 ±70 ±80 μA max A S/H In+ and S/H In– 200 || 1.2 kΩ || pF typ C S/H In+ – S/H In– ±3.0 V typ C S/H In+ and S/H In– ±3.2 V typ C μA/V max A V typ C Common-Mode Rejection Ratio (CMRR) ±2 Output Voltage Compliance CHOLD Pin Output Current CHOLD Pin ±5 Output Impedance CHOLD Pin 0.5 || 1.2 Transconductance S/H In+ – S/H In– to CHOLD Current VIN = 300mVPP 35 ±50 ±55 ±60 ±3.5 ±3 21 ±2.5 20 ±2.0 mA min A MΩ || pF typ C 19 mA/V min A Minimum Hold Logic High Voltage Tracking High 2 2 2 V max A Maximum Hold Logic Low Voltage Holding Low 0.8 0.8 0.8 V min A Logic High Input Current VHOLD = +5V ±0.5 ±1 ±1 ±1.2 μA max A Logic Low Input Current VHOLD = 0V 140 200 220 230 μA max A ±2 ±50 ±55 ±60 μA/V max A V typ C Minimum Operating Voltage ±4 ±4 ±4 V min B Maximum Operating Voltage ±6.2 ±6.2 ±6.2 V max A Comparator Power-Supply Rejection Ratio (PSRR) S/H In+ = S/H In– = 0V, Track Mode POWER SUPPLY Specified Operating Voltage ±5 Maximum Quiescent Current RQ = 300Ω (4) 13 14 16 17 mA max A Minimum Quiescent Current RQ = 300Ω (4) 13 12 11 9 mA min A –40 to +85 °C typ C THERMAL CHARACTERISTICS Specified Operating Range D Package Thermal Resistance θ JA Junction-to-Ambient DGS MSOP-10 125 °C/W typ C D SO-14 100 °C/W typ C (4) SO-14 package only. Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 5 OPA615 SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009...................................................................................................................................... www.ti.com TYPICAL CHARACTERISTICS TA = +25°C and IQ = 13mA, unless otherwise noted. OTA OTA TRANSCONDUCTANCE vs FREQUENCY 120 80 IQ = 13mA (72mA/V), RQ = 300Ω VIN = 100mVPP 50Ω 50Ω Transconductance (mA/V) Transconductance (mA/V) VIN IQ = 14.3mA (89mA/V), RQ = 0Ω 120 IOUT VIN = 10mVPP 100 OTA TRANSCONDUCTANCE vs QUIESCENT CURRENT 60 40 IQ = 9.6mA (28mA/V), RQ = 2kΩ 20 0 100 80 60 IOUT VIN 40 30 0 10k 1M 10M 100M 1G 8 9 10 Frequency (Hz) 13 14 15 OTA TRANSFER CHARACTERISTICS 100 20 90 15 I O UT IQ = 14.3mA OTA Output Current (mA) Transconductance (mA/V) 12 Figure 2. OTA TRANSCONDUCTANCE vs INPUT VOLTAGE 80 70 60 IQ = 13mA 50 I Q = 9.6mA 40 VIN 50Ω 10 50Ω 5 0 −5 IQ = 13mA IQ = 9.6mA −10 IQ = 14.3mA −15 30 Small−Signal Around Input Voltage 20 −50 −40 −30 −20 −10 0 10 20 30 40 −20 −200 50 −150 −100 Input Voltage (mV) 0 50 100 150 200 Figure 4. OTA-C SMALL SIGNAL PULSE RESPONSE OTA-C LARGE SIGNAL PULSE RESPONSE 0.15 3 fIN = 10MHz G = +1V/V VIN = 0.2VPP 2 Output Voltage (V) 0.10 −50 OTA Input Voltage (mV) Figure 3. Output Voltage (V) 11 Quiescent Current (mA) Figure 1. 0.05 0 −0.05 −0.10 fIN = 10MHz G = +1V/V VIN = 4VPP 1 0 −1 −2 −0.15 −3 Time (10ns/div) Time (10ns/div) Figure 5. 6 50Ω 50Ω Figure 6. Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 OPA615 www.ti.com...................................................................................................................................... SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009 TYPICAL CHARACTERISTICS (continued) TA = +25°C and IQ = 13mA, unless otherwise noted. OTA B-INPUT RESISTANCE vs QUIESCENT CURRENT OTA C-OUTPUT RESISTANCE vs QUIESCENT CURRENT 18 OTA C−Output Resistance (MΩ ) OTA B−Input Resistance (MΩ ) 140 120 100 80 60 40 20 0 16 14 12 10 8 6 4 2 0 8 9 10 11 12 13 14 15 8 9 10 Quiescent Current (mA) 12 13 14 15 Figure 7. Figure 8. OTA E-OUTPUT RESISTANCE vs QUIESCENT CURRENT OTA INPUT VOLTAGE AND CURRENT NOISE DENSITY 100 160 Voltage Noise Density (nV/√Hz) Current Noise Density (pA/√Hz) OTA E−Output Resistance (Ω) 180 140 120 100 80 60 40 20 8 9 10 11 12 13 14 E−Input Current Noise (21.0pA/√Hz) 10 B−Input Voltage Noise (4.6nV/√Hz) B−Input Current Noise (2.5pA/√Hz) 1 100 0 15 Figure 9. 1.0 0.05 B−Input Bias Current 0 0 −0.5 −0.05 B−Input Offset Voltage −1.5 −20 0 20 40 60 80 100 −0.10 120 B−Input Bias Current (µV) 1.5 −2.0 −40 100k 1M 10M OTA TRANSFER CHARACTERISTICS vs INPUT VOLTAGE 0.10 OTA−C Output Current (mA) 2.0 −1.0 10k Figure 10. OTA B-INPUT OFFSET VOLTAGE AND BIAS CURRENT vs TEMPERATURE 0.5 1k Frequency (Hz) Quiescent Current (mA) B−Input Offset Voltage (mV) 11 Quiescent Current (mA) 35 Degenerated E−Input IQ = 14.3mA 30 RE = RL = 100Ω 25 IO UT 20 100Ω 15 VIN IQ = 9.6mA 10 100Ω 5 0 IQ = 13mA −5 −10 −15 −20 −25 −30 −35 −3.5 −3 −2.5 −2 −1.5 −1 −0.5 0 0.5 1 1.5 2 2.5 3 3.5 Ambient Temperature (_ C) OTA−B Input Voltage (mV) Figure 11. Figure 12. Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 7 OPA615 SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009...................................................................................................................................... www.ti.com TYPICAL CHARACTERISTICS (continued) TA = +25°C and IQ = 13mA, unless otherwise noted. OTA-E OUTPUT PULSE RESPONSE VO = 0.6VPP VO = 1.4VPP −3 Gain (dB) Output Voltage (mV) 0 VO = 5VPP −6 VO = 2.8VPP −9 100Ω V IN 50Ω −12 VO = 0.2VPP VO 200 2.0 160 1.6 120 1.2 0.8 80 Large−Signal ±1.6V Right Scale 40 Small−Signal ±80mV Left Scale 0 −40 −80 0 −0.4 100Ω −0.8 VIN −120 50Ω VO 500Ω −160 500Ω 0.4 1M 10M 100M −1.2 −1.6 −2.0 −200 −15 Output Voltage (V) OTA-E OUTPUT FREQUENCY RESPONSE 3 Time (20ns/div) 1G Frequency (Hz) Figure 13. Figure 14. OTA-C OUTPUT FREQUENCY RESPONSE OTA-E OUTPUT HARMONIC DISTORTION vs FREQUENCY 3 −40 0 −45 VO = 0.6VPP −3 Gain (dB) Harmonic Distortion (dBc) VOUT = 1.4VPP VO = 1.4VPP −6 VO = 0.2VPP VO −9 V IN 100Ω VO = 2.8VPP 50Ω −12 100Ω −50 3rd−Harmonic −55 2nd−Harmonic −60 V IN −65 50Ω V OUT 10 0Ω VO = 5VPP −70 −15 1M 10M 100M 1 1G 10 Figure 15. Figure 16. OTA-C OUTPUT HARMONIC DISTORTION vs FREQUENCY OTA QUIESCENT CURRENT vs RQ −20 16 VO U T VIN V OUT = 1.4VPP 15 100Ω 50Ω −30 Quiescent Current (mA) Harmonic Distortion (dBc) −25 100Ω −35 −40 −45 −50 3rd−Harmonic −55 14 13 12 +IQ 11 10 −IQ 9 2nd−Harmonic −60 8 1 10 100 0.1 Frequency (MHz) 1 10 100 1k 10k 100k R Q (Ω) Figure 17. 8 100 Frequency (MHz) Frequency (Hz) Figure 18. Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 OPA615 www.ti.com...................................................................................................................................... SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009 TYPICAL CHARACTERISTICS (continued) TA = +25°C and IQ = 13mA, unless otherwise noted. SOTA (Sampling Operational Transconductance Amplifier) SOTA TRANSCONDUCTANCE vs FREQUENCY SOTA TRANSCONDUCTANCE vs QUIESCENT CURRENT 40 40 Transconductance (mA/V) Transconductance (mA/V) VIN = 10mVPP 30 20 VIN 10 50Ω SOTA ∞ IO UT 30 20 10 50Ω RQ Adjusted +5V Hold Control 0 0 1M 10M 100M 8 1G 9 10 Figure 19. 13 14 15 SOTA TRANSFER CHARACTERISTICS 45 8 40 6 SOTA Output Current (mA) Transconductance (mA/V) 12 Figure 20. SOTA TRANSCONDUCTANCE vs INPUT VOLTAGE 35 30 25 20 15 10 4 2 0 −2 −4 −6 5 Small−Signal Around Input Voltage 0 −100 −80 −60 −40 −20 0 20 40 60 80 −8 −200 100 −150 −100 Input Voltage (mV) 50 100 150 200 SOTA PULSE RESPONSE 150 fIN = 20MHz RL = 50Ω IOUT = 4mAPP tRISE = 2ns 100 Output Voltage (mV) 100 0 Figure 22. SOTA PULSE RESPONSE 150 −50 SOTA Input Voltage (mV) Figure 21. Output Voltage (mV) 11 Quiescent Current (mA) Frequency (Hz) 50 0 −50 fIN = 20MHz RL = 50Ω IOUT = 4mAPP tRISE = 10ns 50 0 −50 −100 −100 Hold Control = +5V −150 Hold Control = +5V −150 Time (10ns/div) Time (10ns/div) Figure 23. Figure 24. Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 9 OPA615 SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009...................................................................................................................................... www.ti.com TYPICAL CHARACTERISTICS (continued) TA = +25°C and IQ = 13mA, unless otherwise noted. SOTA PROPAGATION DELAY vs OVERDRIVE SOTA PROPAGATION DELAY vs TEMPERATURE 1.3 2.0 1.8 Propagation Delay (ns) Propagation Delay (ns) Negative 1.2 Positive 1.1 1.0 100W VOD VOD SOTA GND 0.9 VOD 100W 1.6 Falling Edge 1.4 Rising Edge 1.2 1.0 0.8 0.6 0.4 0.2 0 0.8 0 200 400 600 800 1000 −40 1200 −20 0 20 Input Voltage (mV) 40 60 80 100 120 Temperature (_ C) Figure 25. Figure 26. SOTA PROPAGATION DELAY vs SLEW RATE SOTA SWITCHING TRANSIENTS 1.4 10 100Ω VOUT Switching Transient (mV) Propagation Delay (ns) 1.3 1.2 Negative 1.1 1.0 VIN = 1.2Vpp +0.6V 0.9 Positive ON −OFF 50Ω 5 100Ω TTL OFF −ON 0 −5 0V −0.6V −10 0.8 0 1 2 3 4 5 6 7 8 9 Time (10ns/div) 10 Rise Time (ns) Figure 28. SOTA HOLD COMMAND DELAY TIME SOTA BANDWIDTH vs OUTPUT CURRENT SWING 2.0 1.5 1.0 Output Voltage (mV) 0.5 0 −50 150 100 50 6 IOUT = 0.5mAPP 3 0 Gain (dB) 2.5 Hold Command (V) Figure 27. IOUT = 4mAPP −3 −6 IOUT = 2mAPP −9 0 −50 −12 −100 −15 −150 Time (10ns/div) 1M 10M 100M 1G 2G Frequency (Hz) Figure 29. 10 Figure 30. Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 OPA615 www.ti.com...................................................................................................................................... SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009 TYPICAL CHARACTERISTICS (continued) TA = +25°C and IQ = 13mA, unless otherwise noted. SOTA FEEDTHROUGH REJECTION vs FREQUENCY SOTA COMMON-MODE REJECTION vs FREQUENCY −20 0 Hold Control = 0V (Off−Isolation) Common−Mode Rejection (dB) Feedthrough Rejection (dB) 0 −40 −60 −80 −100 −120 1M 10M 100M −20 Hold Control = 5V V+ = V− −40 −60 −80 −100 −120 100k 1G 1M 10M Frequency (Hz) 1G Figure 31. Figure 32. SOTA INPUT BIAS CURRENT vs TEMPERATURE SOTA OUTPUT BIAS CURRENT vs TEMPERATURE 50 0.40 40 0.30 Positive Input 0.25 Negative Input Output Bias Current (µA) 0.35 Input Bias Current (µA) 100M Frequency (Hz) 0.20 0.15 0.10 Hold Control = 5V V+ = V− = 0V 30 20 10 0 −10 −20 −30 −40 0.05 0 −40 −20 0 20 40 60 80 100 120 −50 −40 −20 0 20 40 60 80 100 120 Temperature (_ C) Temperature (_C) Figure 33. Figure 34. Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 11 OPA615 SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009...................................................................................................................................... www.ti.com DISCUSSION OF PERFORMANCE The OPA615, which contains a wideband Operational Transconductance Amplifier (OTA) and a fast sampling comparator (SOTA), represents a complete subsystem for very fast and precise DC restoration, offset clamping and correction to GND or to an adjustable reference voltage, and low frequency hum suppression of wideband operational or buffer amplifiers. Although the IC was designed to improve or stabilize the performance of complex, wideband video signals, it can also be used as a sample-and-hold amplifier, high-speed integrator, peak detector for nanosecond pulses, or as part of a correlated double sampling system. A wideband Operational Transconductance Amplifier (OTA) with a high-impedance cascode current source output and a fast and precise sampling comparator sets a new standard for high-speed sampling applications. Both the OTA and the sampling comparator can be used as stand-alone circuits or combined to create more complex signal processing stages such as sample-and-hold amplifiers. The OPA615 simplifies the design of input amplifiers with high hum suppression; clamping or DC-restoration stages in professional broadcast equipment, high-resolution CAD monitors and information terminals; and signal processing stages for the energy and peak value of nanoseconds pulses. This device also eases the design of high-speed data acquisition systems behind a CCD sensor or in front of an analog-to-digital converter (ADC). An external resistor on the SO-14 package, RQ, allows the user to set the quiescent current. RQ is connected from Pin 1 (IQ adjust) to –VCC. It determines the operating currents of the OTA section and controls the bandwidth and AC behavior as well as the transconductance of the OTA. Besides the quiescent current setting feature, a Proportional-to-Absolute-Temperature (PTAT) supply current control will increase the quiescent current versus temperature. This variation holds the transconductance (gm) of the OTA and comparator relatively constant versus temperature. The circuit parameters listed in the specification table are measured with RQ set to 300Ω, giving a nominal quiescent current at 13mA. While not always shown in the application circuits, this RQ = 300Ω is required to get the 13mA quiescent operating current. 12 OPERATIONAL TRANSCONDUCTANCE AMPLIFIER (OTA) SECTION OVERVIEW The symbol for the OTA section is similar to that of a bipolar transistor, and the self-biased OTA can be viewed as either a quasi-ideal transistor or as a voltage-controlled current source. Application circuits for the OTA look and operate much like transistor circuits—the bipolar transistor is also a voltage-controlled current source. Like a transistor, it has three terminals: a high-impedance input (base) optimized for a low input bias current of 0.3μA, a low-impedance input/output (emitter), and the high-impedance current output (collector). The OTA consists of a complementary buffer amplifier and a subsequent complementary current mirror. The buffer amplifier features a Darlington output stage and the current mirror has a cascoded output. The addition of this cascode circuitry increases the current source output resistance to 1.2MΩ. This feature improves the OTA linearity and drive capabilities. Any bipolar input voltage at the high impedance base has the same polarity and signal level at the low impedance buffer or emitter output. For the open-loop diagrams, the emitter is connected to GND; the collector current is then determined by the voltage between base and emitter times the transconductance. In application circuits (Figure 36b), a resistor RE between the emitter and GND is used to set the OTA transfer characteristics. The following formulas describe the most important relationships. re is the output impedance of the buffer amplifier (emitter) or the reciprocal of the OTA transconductance. Above ±5mA, the collector current, IC, will be slightly less than indicated by the formula. IC + V IN r E ) RE or RE + V IN * rE IC (1) The RE resistor may be bypassed by a relatively large capacitor to maintain high AC gain. The parallel combination of RE and this large capacitor form a high-pass filter, enhancing the high frequency gain. Other cases may require an RC compensation network in parallel to RE to optimize the high-frequency response. The large-signal bandwidth (VO = 1.4VPP) measured at the emitter achieves 770MHz. The frequency response of the collector is directly related to the resistor value between the collector and GND; it decreases with increasing resistor values, because of the low-pass filter formed with the OTA C-output capacitance. Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 OPA615 www.ti.com...................................................................................................................................... SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009 Figure 35 shows a simplified block diagram of the OPA615 OTA. Both the emitter and the collector outputs offer a drive capability of ±20mA for driving low impedance loads. The emitter output is not current-limited or protected. Momentary shorts to GND should be avoided, but are unlikely to cause permanent damage. +VCC (13) B (3) E (2) +1 While the OTA function and labeling appear similar to those of a transistor, it offers essential distinctive differences and improvements: 1) The collector current flows out of the C terminal for a positive B-to-E input voltage and into it for negative voltages; 2) A common emitter amplifier operates in non-inverting mode while the common base operates in inverting mode; 3) The OTA is far more linear than a bipolar transistor; 4) The transconductance can be adjusted with an external resistor; 5) As a result of the PTAT biasing characteristic, the quiescent current increases as shown in the typical performance curve vs temperature and keeps the AC performance constant; 6) The OTA is self-biased and bipolar; and 7) The output current is approximately zero for zero differential input voltages. AC inputs centered on zero produce an output current centered on zero. BASIC APPLICATION CIRCUITS C (12) Most application circuits for the OTA section consist of a few basic types which are best understood by analogy to discrete transistor circuits. Just as the transistor has three basic operating modes—common emitter, common base, and common collector—the OTA has three equivalent operating modes; common-E, common-B, and common-C (see Figure 36, Figure 37 and Figure 38). Figure 36 shows the OTA connected as a Common-E amplifier, which is equivalent to a common emitter transistor amplifier. Input and output can be ground-referenced without any biasing. The amplifier is noninverting because a current flowing out of the emitter will also flow out of the collector as a result of the current mirror shown in Figure 35. +VCC (5) Figure 35. Simplified OTA Block Diagram V+ RB RL VO 100Ω Inverting Gain VOS ≈ several volts VI RB VI VO 12 C 3 B OTA RL NoninvertingGain VOS ≈ 0 E 2 RE RE V− Single Transistor (b) Common−E Amplifier for OTA (a) Common Emitter Amplifier Transconductance varies over temperature. Transconductance remains constant over temperature. Figure 36. a) Common Emitter Amplifier Using a Discrete Transistor; b) Common-E Amplifier Using the OTA Portion of the OPA615 Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 13 OPA615 SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009...................................................................................................................................... www.ti.com Figure 37 shows the Common-C amplifier. It constitutes an open-loop buffer with low offset voltage. Its gain is approximately 1 and will vary with the load. 12 C V+ 100Ω VI Figure 38 shows the Common-B amplifier. This configuration produces an inverting gain, and the input is low-impedance. When a high impedance input is needed, it can be created by inserting a buffer amplifier (such as the BUF602) in series. 3 B V+ OTA G≈1 VOS ≈ 0 G=− RL E 2 VI VO RE V− Single Transistor (a) Common Collector Amplifier (Emitter Follower) RE G= RO = 1 1+ gm x RE 100Ω RE ≈ 1 3 B ≈ − RL RE 12 C OTA VO Inverting Gain VOS ≈ 0 RL E 2 VI Single Transistor (a) Common−Base Amplifier 1 gm Figure 37. a) Common Collector Amplifier Using a Discrete Transistor; b) Common-C Amplifier Using the OTA Portion of the OPA615 14 Noninverting Gain VOS ≈ several volts (b) Common−C Amplifier for OTA (Buffer) 1 1 gm VO VO G≈1 VOS ≈ 0.7V RL RE + RE VI (b) Common−B Amplifier for OTA Figure 38. a) Common Base Amplifier Using a Discrete Transistor; b) Common-B Amplifier Using the OTA Portion of the OPA615 Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 OPA615 www.ti.com...................................................................................................................................... SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009 SAMPLING COMPARATOR The OPA615 sampling comparator features a very short switching (2.5ns) propagation delay and utilizes a new switching circuit architecture to achieve excellent speed and precision. It provides high impedance inverting and noninverting analog inputs, a high-impedance current source output and a TTL-CMOS-compatible Hold Control Input. The sampling comparator consists of an operational transconductance amplifier (OTA), a buffer amplifier, and a subsequent switching circuit. This combination is subsequently referred to as the Sampling Operational Transconductance Amplifier (SOTA). The OTA and buffer amplifier are directly tied together at the buffer outputs to provide the two identical high-impedance inputs and high open-loop transconductance. Even a small differential input voltage multiplied with the high transconductance results in an output current—positive or negative—depending upon the input polarity. This characteristic is similar to the low or high status of a conventional comparator. The current source output features high output impedance, output bias current compensation, and is optimized for charging a capacitor in DC restoration, nanosecond integrators, peak detectors and S/H circuits. The typical comparator output current is ±5mA and the output bias current is minimized to typically ±10μA in the sampling mode. This innovative circuit achieves the high slew rate representative of an open-loop design. In addition, the acquisition slew current for a hold or storage capacitor is higher than standard diode bridge and switch configurations, removing a main contributor to the limits of maximum sampling rate and input frequency. The switching circuits in the OPA615 use current steering (versus voltage switching) to provide improved isolation between the switch and analog sections. This design results in low aperture time sensitivity to the analog input signal, reduced power supply and analog switching noise. Sample-to-hold peak switching charge injection is 40fC. The additional offset voltage or switching transient induced on a capacitor at the current source output by the switching charge can be determined by the following formula: Offset (V) + Charge (pC) CHTotal (pF) (2) The switching stage input is insensitive to the low slew rate performance of the hold control command and compatible with TTL/CMOS logic levels. With TTL logic high, the comparator is active, comparing the two input voltages and varying the output current accordingly. With TTL logic low, the comparator output is switched off, showing a very high impedance to the hold capacitor. DESIGN-IN TOOLS Demonstration Fixture Two printed circuit boards (PCBs) are available to assist in the initial evaluation of circuit performance using the OPA615. The demonstration fixture is offered free of charge as an unpopulated PCB, delivered with a user's guide. The summary information for this fixture is shown in Table 2. Table 2. OPA615 Demonstration Fixtures PRODUCT PACKAGE ORDERING NUMBER LITERATURE NUMBER OPA615ID SO-14 DEM-OPA-SO-1C SBOU039 OPA615IDGS MSOP-10 DEM-OPA-MSOP-1A SBOU042 The demonstration fixture can be requested at the Texas Instruments web site (www.ti.com) through the OPA615 product folder. Macromodel and Applications Support Computer simulation of circuit performance using SPICE is often a quick way to analyze the performance of analog circuits and systems. This is particularly true for video and RF amplifier circuits where parasitic capacitance and inductance can have a major effect on circuit performance. A SPICE model for the OPA615 is available through the TI web page (www.ti.com). This model predicts typical small-signal AC, transient steps, DC performance, and noise under a wide variety of operating conditions. The model includes the noise terms found in the electrical specifications of the data sheet. However, the model does not attempt to distinguish between package types in their small-signal AC performance. The applications department is also available for design assistance. Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 15 OPA615 SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009...................................................................................................................................... www.ti.com APPLICATION INFORMATION The OPA615 operates from ±5V power supplies (±6.2V maximum). Absolute maximum is ±6.5V. Do not attempt to operate with larger power supply voltages or permanent damage may occur. Power-supply bypass capacitors should be located as close as possible to the device pins. Solid tantalum capacitors are generally best. See Board Layout at the end of the applications discussion for further suggestions on layout. BASIC CONNECTIONS Figure 39 shows the basic connections required for operation. These connections are not shown in subsequent circuit diagrams. RB (25Ω to 200Ω) CHOLD 9 GND 4 3 Base 2 (20Ω to 200Ω) Hold 7 Control Switching Stage Emitter OTA 12 Collector Sampling Comparator (SC) S/H In+ 10 SOTA ∞ Biasing 1 IQ Adjust S/H In− 11 RQ 13 +VCC +5V + 2.2µF 10nF 470pF 5 RQ = 300Ω sets approximately I Q = 13mA −VCC −5V 470pF 10nF + 2.2µF Solid Tantalum Figure 39. Basic Connections 16 Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 OPA615 www.ti.com...................................................................................................................................... SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009 DC-RESTORE SYSTEM Figure 40 and Figure 41 offer two possible DC-restore systems using the OPA615. Figure 41 implements a DC-restore function as a unity-gain amplifier. As can be expected from its name, this DC-restore circuit does not provide any amplification. HCL 7 SOTA 4 In applications where some amplification is needed, consider using the circuit design shown in Figure 40. 10 100Ω 11 12 CHOLD OPA615 100Ω 100Ω OTA 3 HCL 10 7 VOUT 2 VIN 100Ω 4 SOTA 11 OPA615 12 CHOLD 3 OTA VOUT 2 VIN Figure 41. DC Restoration of a Buffer Amplifier 100Ω 100Ω = VIN x R1 For either of these circuits to operate properly, the source impedance needs to be low, such as the one provided by the output of a closed-loop amplifier or buffer. Consider the video input signal shown in Figure 42, and the complete DC restoration system shown in Figure 40. This signal is amplified by the OTA section of the OPA615 by a gain of: R2 R1 R2 Figure 40. Complete DC Restoration System G+) 100 89 70 59 41 W Y CY GRN MAG 30 R R2 R1 11 0 BLU BLK 100 IRE UNITS 60 40 7.5 20 10 0 40 IRE 1VPP 80 −20 BACK PORCH −40 BLANKING LUMINANCE + CHROMINANCE FRONT PORCH SYNC TIP BREEZEWAY COLOR BURST Figure 42. NTSC Horizontal Scan Line Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 17 OPA615 SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009...................................................................................................................................... www.ti.com The DC restoration is done by the SOTA section by sampling the output signal at an appropriate time. The sampled section of the signal is then compared to a reference voltage that appears on the non-inverting input of the SOTA (pin 10), or ground in Figure 40. When the SOTA is sampling, it is charging or discharging the CHOLD capacitor depending on the level of the output signal sampled. The detail of an appropriate timing is illustrated in Figure 43. 100 0V IRE UNITS Input Voltage 80 60 40 7.5 20 10 0 −20 −40 HCL Sample Hold 100 Output Voltage IRE UNITS 80 0V 60 40 7.5 20 10 0 −20 −40 Figure 43. DC-Restore Timing 18 Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 OPA615 www.ti.com...................................................................................................................................... SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009 CLAMPED VIDEO/RF AMPLIFIER Another circuit example for the preamplifier and the clamp circuit is shown in Figure 44. The preamplifier uses the wideband, low noise OPA656, again configured in a gain of +2V/V. Here, the OPA656 has a typical bandwidth of 200MHz with a settling time of about 21ns (0.02%) and offers a low bias current JFET input stage. HCL 100Ω 7 2 11 4 OTA 3 OPA615 SAMPLE-AND-HOLD AMPLIFIER With a control propagation delay of 2.5ns and 730MHz bandwidth, the OPA615 can be used advantageously in a high-speed sample-and-hold amplifier. Figure 45 illustrates this configuration. CHOLD RE The external capacitor (CHOLD) allows for a wide range of flexibility. By choosing small values, the circuit can be optimized for a short clamping period or with high values for a low droop rate. Another advantage of this circuit is that small clamp peaks at the output of the switching comparator are integrated and do not cause glitches in the signal path. 100Ω VREF Hold /Track SOTA 10 12 100Ω R1 R2 300Ω 150Ω VIN 100Ω 300Ω 50Ω CB 11 12 OPA615 10 7 SOTA 100Ω 4 CHOLD 22pF 3 OTA 2 50Ω VOUT OPA656 VOUT 300Ω • Current Control VIN RB • Non−Inverting 300Ω Figure 44. Clamped Video/RF Amplifier Figure 45. Sample-and-Hold Amplifier The video signal passes through the capacitor CB, blocking the DC component. To restore the DC level to the desired baseline, the OPA615 is used. The inverting input (pin 11) is connected to a reference voltage. During the high time of the clamp pulse, the switching comparator (SOTA) will compare the output of the op amp to the reference level. Any voltage difference between those pins will result in an output current that either charges or discharges the hold capacitor, CHOLD. This charge creates a voltage across the capacitor, which is buffered by the OTA. Multiplied by the transconductance, the voltage will cause a current flow in the collector, C, terminal of the OTA. This current will level-shift the OPA656 up to the point where its output voltage is equal to the reference voltage. This level-shift also closes the control loop. Because of the buffer, the voltage across the CHOLD stays constant and maintains the baseline correction during the off-time of the clamp pulse. To illustrate how the digitization is realized in the Figure 45 circuit, Figure 46 shows a 100kHz sinewave being sampled at a rate of 1MHz. The output signal used here is the IOUT output driving a 50Ω load. 1MHz SAMPLE−AND−HOLD OF A 100kHz SINEWAVE 5 Output Voltage (V) 3 2 1 +2.5 0 +1.5 +0.5 −0.5 Hold−and−Track Signal (V) 4 −1.5 −2.5 Time (1µs/div) Figure 46. 1MHz Sample-and-Hold of a 100kHz Sine Wave Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 19 OPA615 SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009...................................................................................................................................... www.ti.com Integrator for ns-Pulses Phase Detector for Fast PLL Systems The integrator for ns-pulses using the OPA615 (shown in Figure 47) makes use of the fast comparator and its current-mode output. Placing the hold-control high, a narrow pulse charges the capacitor, increasing the average output voltage. To minimize ripples at the inverting input and maximize the capacitor charge, a T-network is used in the feedback path. Figure 49 shows the circuit for a phase detector for fast PLL systems. Given a reference pulse train fREF and a pulse train input signal fIN out of phase, the SOTA of the OPA615 acts in this circuit as a comparator, either charging or discharging the capacitor. This voltage is then buffered by the OTA and fed to the VCO. Hold Control 150Ω VIN 10 SOTA 50Ω 4 OTA 10 f IN 50Ω 75Ω VOUT 620Ω SOTA 4 7 27pF 2 12 OPA615 100Ω 100Ω 3 11 11 fR EF 12 7 75Ω OTA 3 C IN T 2 75Ω VO UT +5V 820Ω 1µF f IN √N fO UT fR EF Figure 47. Integrator for ns-Pulses fIN Fast Pulse Peak Detector I OU T A circuit similar to that shown in Figure 47 (the integrator for ns-pulses) can be devised to detect and isolate positive pulses from negative pulses. This circuit, shown in Figure 48, uses the OPA615 as well as the BUF602. This circuit makes use of diodes to isolate the positive-going pulses from the negative-going pulses and charge-different capacitors. Hold Control 50Ω 100Ω 4 150Ω 50Ω 10 11 VOU T Phase fR EF fO UT = f RE F x N Figure 49. Phase Detector For Fast PLL-Systems −VOUT 8 27pF 100Ω VIN +1 VOU T VCO BUF602 12 7 SOTA 100Ω 4 3 27pF OPA615 OTA 2 50Ω +VOUT 300Ω Figure 48. Fast Bipolar Peak Detector 20 Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 OPA615 www.ti.com...................................................................................................................................... SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009 CORRELATED DOUBLE SAMPLER The signal coming from the CCD is applied to the two sample-and-hold amplifiers, with their outputs connected to the difference amplifier. The timing diagram clarifies the operation (see Figure 52). At time t1, the sample and hold (S/H1) goes into the hold mode, taking a sample of the reset level including the noise. This voltage (VRESET) is applied to the noninverting input of the difference amplifier. At time t2, the sample-and-hold (S/H2) will take a sample of the video level, which is VRESET – VVIDEO. The output voltage of the difference amplifier is defined by the equation VOUT = VIN+ – VIN–. The sample of the reset voltage contains the kT/C noise, which is eliminated by the subtraction of the difference amplifier. Noise is the limiting factor for the resolution in a CCD system, where the kT/C noise is dominant (see Figure 51). To reduce this noise, imaging systems use a circuit called a Correlated Double Sampler (CDS). The name comes from the double sampling technique of the CCD charge signal. A CDS using two OPA615s and one OPA694 is shown in Figure 50. The first sample (S1) is taken at the end of the reset period. When the reset switch opens again, the effective noise bandwidth changes because of the large difference in the switch RON and ROFF resistance. This difference causes the dominating kT/C noise essentially to freeze in its last point. The double sampling technique also reduces the white noise. The white noise is part of the reset voltage (VRESET) as well as of the video amplitude (VRESET – VVIDEO). With the assumption that the noise of the noise of the second sample was unchanged from the instant of the first sample, the noise amplitudes are the same and are correlated in time. Therefore, the noise can be reduced by the CDS function. The other sample (S2) is taken during the video portion of the signal. Ideally, the two samples differ only by a voltage corresponding to the transferred charge signal. This is the video level minus the noise (ΔV). The CDS function will eliminate the kT/C noise as well as much of the 1/f and white noise. Figure 52 is a block diagram of a CDS circuit. Two sample-and-hold amplifiers and one difference amplifier constitute the correlated double sampler. VHOLD1 100Ω VIN1 50Ω 11 12 7 10 100Ω SOTA 4 402Ω 3 OTA 27pF 402Ω 2 300Ω 402Ω OPA694 VOUT 300Ω 402Ω VHOLD2 100Ω VIN2 50Ω 11 12 7 10 100Ω SOTA 4 3 OTA 27pF 2 300Ω 300Ω Figure 50. Correlated Double Sampler Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 21 OPA615 SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009...................................................................................................................................... www.ti.com Simplified CCD Output Signal S1 kT/C −Noise PP ∆V Reset Level S2 Video Level NOTE: Signals are out of scale. Figure 51. Improving SNR with Correlated Double Sampling S/H1 VRESET VOUT = VIN+ − VIN− VIN S/H2 t2 Video Hold VIN VRESET − VVIDEO Difference Amplifier t1 Reset Hold S1 t1 S2 t2 0V Video Out Figure 52. CDS: Circuit Concept 22 Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 OPA615 www.ti.com...................................................................................................................................... SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009 BOARD LAYOUT GUIDELINES Achieving optimum performance with a highfrequency amplifier such as the OPA615 requires careful attention to printed circuit board (PCB) layout parasitics and external component types. Recommendations that will optimize performance include: d) Connections to other wideband devices on the board may be made with short direct traces or through onboard transmission lines. For short connections, consider the trace and the input to the next device as a lumped capacitive load. Relatively wide traces (50mils to 100mils) should be used, preferably with ground and power planes opened up around them. a) Minimize parasitic capacitance to any AC ground for all of the signal I/O pins. Parasitic capacitance on the output and inverting input pins can cause instability; on the non-inverting input, it can react with the source impedance to cause unintentional bandlimiting. To reduce unwanted capacitance, a window around the signal I/O pins should be opened in all of the ground and power planes around those pins. Otherwise, ground and power planes should be unbroken elsewhere on the board. e) Socketing a high-speed part such as the OPA615 is not recommended. The additional lead length and pin-to-pin capacitance introduced by the socket can create an extremely troublesome parasitic network which can make it almost impossible to achieve a smooth, stable frequency response. Best results are obtained by soldering the OPA615 directly onto the PCB. b) Minimize the distance (< 0.25") from the power supply pins to high frequency 0.1μF decoupling capacitors. At the device pins, the ground and power plane layout should not be in close proximity to the signal I/O pins. Avoid narrow power and ground traces to minimize inductance between the pins and the decoupling capacitors. The power-supply connections should always be decoupled with these capacitors. An optional supply-decoupling capacitor across the two power supplies (for bipolar operation) will improve 2nd-harmonic distortion performance. Larger (2.2μF to 6.8μF) decoupling capacitors, effective at a lower frequency, should also be used on the main supply pins. These may be placed somewhat farther from the device and may be shared among several devices in the same area of the PCB. The OPA615 is built using a very high-speed, complementary bipolar process. The internal junction breakdown voltages are relatively low for these very small geometry devices. These breakdowns are reflected in the Absolute Maximum Ratings table where an absolute maximum ±6.5V supply is reported. All device pins have limited ESD protection using internal diodes to the power supplies, as shown in Figure 53. c) Careful selection and placement of external components will preserve the high frequency performance of the OPA615. Resistors should be a very low reactance type. Surface-mount resistors work best and allow a tighter overall layout. Metal-film and carbon composition, axially-leaded resistors can also provide good high frequency performance. Again, keep these leads and PCB trace length as short as possible. Never use wirewound-type resistors in a high frequency application. Other network components, such as noninverting input termination resistors, should also be placed close to the package. INPUT AND ESD PROTECTION +VCC External Pin Internal Circuitry −VCC Figure 53. Internal ESD Protection These diodes also provide moderate protection to input overdrive voltages above the supplies. The protection diodes can typically support 30mA continuous current. Where higher currents are possible (for example, in systems with ±15V supply parts driving into the OPA615), current-limiting series resistors should be added into the two inputs. Keep these resistor values as low as possible since high values degrade both noise performance and frequency response. Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 23 OPA615 SBOS299E – FEBRUARY 2004 – REVISED SEPTEMBER 2009...................................................................................................................................... www.ti.com REVISION HISTORY NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision D (August 2008) to Revision E ................................................................................................ Page • Corrected y-axis title of Figure 25 ....................................................................................................................................... 10 Changes from Revision C (October 2006) to Revision D ............................................................................................... Page • Changed rating for storage temperature range in Absolute Maximum Ratings table from –40°C to +125°C to –65°C to +125°C .............................................................................................................................................................................. 2 • Clarified hold control pin voltage rating in Absolute Maximum Ratings table ....................................................................... 2 24 Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated Product Folder Link(s): OPA615 PACKAGE OPTION ADDENDUM www.ti.com 6-May-2022 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) Samples (4/5) (6) OPA615ID ACTIVE SOIC D 14 50 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA615ID Samples OPA615IDGSR ACTIVE VSSOP DGS 10 2500 RoHS & Green Call TI | NIPDAUAG Level-2-260C-1 YEAR -40 to 85 BJT Samples OPA615IDGST ACTIVE VSSOP DGS 10 250 RoHS & Green NIPDAUAG Level-2-260C-1 YEAR -40 to 85 BJT Samples OPA615IDR ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA615ID Samples (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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OPA615IDGSR
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