OPA688

® OPA 688 OPA688 OPA 688 For most current data sheet and other product information, visit www.burr-brown.com Unity Gain Stable, Wideband VOLTAGE LIMITING AMPLIFIER TM FEATURES q q q q q q q HIGH LINEARITY NEAR LIMITING FAST RECOVERY FROM OVERDRIVE: 2.4ns LIMITING VOLTAGE ACCURACY: ±15mV –3dB BANDWIDTH (G = +1): 530MHz SLEW RATE: 1000V/µs ±5V AND 5V SUPPLY OPERATION HIGH GAIN VERSION: OPA689 APPLICATIONS q q q q q q q q FAST LIMITING ADC INPUT BUFFER CCD PIXEL CLOCK STRIPPING VIDEO SYNC STRIPPING HF MIXER IF LIMITING AMPLIFIER AM SIGNAL GENERATION NON-LINEAR ANALOG SIGNAL PROCESSING COMPARATOR DESCRIPTION The OPA688 is a wideband, unity gain stable voltage feedback op amp that offers bipolar output voltage limiting. Two buffered limiting voltages take control of the output when it attempts to drive beyond these limits. This new output limiting architecture holds the limiter offset error to ±15mV. The op amp operates linearly to within 30mV of the output limit voltages. The combination of narrow nonlinear range and low limiting offset allows the limiting voltages to be set within 100mV of the desired linear output range. A fast 2.4ns recovery from limiting ensures that overdrive signals will be transparent to the signal channel. Implementing the limiting function at the output, as opposed to the input, gives the specified limiting accuracy for any gain, and allows the OPA688 to be used in all standard op amp applications. Non-linear analog signal processing will benefit from the OPA688’s sharp transition from linear operation to output limiting. The quick recovery time supports high speed applications. The OPA688 is available in an industry standard pinout in PDIP-8 and SO-8 packages. For higher gain, or transimpedance applications requiring output limiting with fast recovery, consider the OPA689. LIMITED OUTPUT RESPONSE 2.5 2.0 Input and Output Voltage (V) 2.10 DETAIL OF LIMITED OUTPUT VOLTAGE 2.05 2.00 VH = –VL = 2.0V G = +2 Output Voltage (V) 1.5 1.0 0.5 0 –0.5 –1.0 –1.5 –2.0 –2.5 Time (200ns/div) VIN VO 1.95 1.90 1.85 1.80 1.75 1.70 1.65 1.60 Time (50ns/div) VO International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111 Twx: 910-952-1111 • Internet: http://www.burr-brown.com/ • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132 ® © 1997 Burr-Brown Corporation PDS-1424D 1 Printed in U.S.A. OPA688 January, 2000 SPECIFICATIONS— VS = ±5V G = +2, RL = 500Ω, RF = 402Ω, VH = –VL = 2V (Figure 1 for AC performance only), unless otherwise noted. OPA688U, P TYP +25°C +25°C GUARANTEED(1) 0°C to +70°C –40°C to +85°C MIN/ TEST MAX LEVEL(2) PARAMETER AC PERFORMANCE (see Figure 1) Small Signal Bandwidth CONDITIONS UNITS Gain-Bandwidth Product (G ≥ +5) Gain Peaking 0.1dB Gain Flatness Bandwidth Large Signal Bandwidth Step Response: Slew Rate Rise/Fall Time Settling Time: 0.05% Spurious Free Dynamic Range Differential Gain Differential Phase Input Noise: Voltage Noise Density Current Noise Density DC PERFORMANCE (VCM = 0) Open Loop Voltage Gain (AOL) Input Offset Voltage Average Drift Input Bias Current(3) Average Drift Input Offset Current Average Drift INPUT Common-Mode Rejection Common-Mode Input Range(4) Input Impedance Differential-Mode Common-Mode OUTPUT Output Voltage Range Current Output, Sourcing Sinking Closed-Loop Output Impedance POWER SUPPLY Operating Voltage, Specified Maximum Quiescent Current, Maximum Minimum Power Supply Rejection Ratio +PSR (Input Referred) OUTPUT VOLTAGE LIMITERS Default Limit Voltage Minimum Limiter Separation (VH – VL) Maximum Limit Voltage Limiter Input Bias Current Magnitude (5) Maximum Minimum Average Drift Limiter Input Impedance Limiter Feedthrough(6) DC Performance in Limit Mode Limiter Offset Op Amp Input Bias Current Shift(3) AC Performance in Limit Mode Limiter Small Signal Bandwidth Limiter Slew Rate(7) Limited Step Response Overshoot Recovery Time Linearity Guardband(8) VO < 0.2Vp-p G = +1, RF = 25Ω G = +2 G = –1 VO < 0.2Vp-p G = +1, RF = 25Ω, VO < 0.2Vp-p VO < 0.2Vp-p VO = 4Vp-p, VH = –VL = 2.5V 4V Step, VH = –VL = 2.5V 0.2V Step 2V Step f = 5MHz, VO = 2Vp-p NTSC, PAL, RL = 500Ω NTSC, PAL, RL = 500Ω f ≥ 1MHz f ≥ 1MHz VO = ±0.5V 530 260 230 290 11 50 145 1000 1.2 7 66 0.02 0.01 6.3 2.0 52 ±2 — +6 — ±0.3 — 57 ±3.3 0.4 || 1 1 || 1 — 150 — 175 — — 100 800 2.6 — 62 — — 7.2 2.5 46 — — 140 — 170 — — 95 770 2.7 — 58 — — 7.8 2.9 44 ±7 ±14 ±13 –60 ±3 ±10 49 ±3.2 — — ±3.9 85 –65 — — ±6 19 12.8 57 ±3.0 200 ±4.3 68 34 40 — — ±40 — — — — 3.0 — — 135 — 160 — — 90 650 3 — 53 — — 8 3.6 43 ±9 ±14 ±20 –90 ±4 ±10 47 ±3.1 — — ±3.8 80 –60 — — ±6 20 11 55 ±2.9 200 ±4.3 70 31 45 — — ±40 — — — — 3.2 — MHz MHz MHz MHz dB MHz MHz V/µs ns ns dB % ° nV/√Hz pA/√Hz dB mV µV/°C µA nA/°C µA nA/°C dB V MΩ || pF MΩ || pF V mA mA Ω V V mA mA dB V mV V µA µA nA/°C MΩ || pF dB mV µA MHz V/µs mV ns mV Typ Min Typ Min Typ Typ Min Min Max Typ Min Typ Typ Max Max Min Max Max Max Max Max Max Min Min Typ Typ Min Min Min Typ Typ Max Max Min Min Min Min Max Max Min Max Typ Typ Max Typ Typ Typ Typ Max Typ C B C B C C B B B C B C C B B A A B A B A B A A C C A A A C C A A A A A B B A A B C C A C C C C B C ±6 — ±12 ±2 — 50 Input Referred, VCM = ±0.5V ±3.2 — — VH = –VL = 4.3V RL ≥ 500Ω VO = 0 VO = 0 G = +1, RF = 25Ω, f < 100kHz ±4.1 105 –85 0.2 ±5 — 15.8 15.8 ±3.9 90 –70 — — ±6 17 14 58 +VS = 4.5V to 5.5V 65 Pins 5 and 8 Limiter Pins Open ±3.3 200 — 54 54 — 2 || 1 –60 ±15 3 450 100 250 2.4 30 ±3.0 200 ±4.3 65 35 — — — VO = 0 f = 5MHz VIN = ±2V (VO – VH) or (VO – VL) VIN = ±2V, VO < 0.02Vp-p 2x Overdrive VIN = 0 to ±2V Step VIN = ±2V to 0V Step f = 5MHz, VO = 2Vp-p ±35 — — — — 2.8 — ® OPA688 2 SPECIFICATIONS— VS = ±5V (CONT) OPA688U, P TYP +25°C –40 to +85 100 125 +25°C — — — GUARANTEED(1) 0°C to +70°C — — — –40°C to +85°C — — — MIN/ TEST MAX LEVEL(2) G = +2, RL = 500Ω, RF = 402Ω, VH = –VL = 2V (Figure 1 for AC performance only), unless otherwise noted. PARAMETER THERMAL CHARACTERISTICS Temperature Range Thermal Resistance P 8-Pin DIP U 8-Pin SO-8 CONDITIONS UNITS °C °C/W °C/W Specification: P, U Junction-to-Ambient Typ Typ Typ C C C NOTES: (1) Junction Temperature = Ambient Temperature for low temperature limit and 25 °C guaranteed specifications. Junction Temperature = Ambient Temperature + 23°C at high temperature limit guaranteed specifications. (2) TEST LEVELS: (A) 100% tested at 25 °C. Over temperature limits by characterization and simulation. (B) Limits set by characterization and simulation. (C) Typical value for information only. (3) Current is considered positive out of node. (4) CMIR tested as < 3dB degradation from minimum CMRR at specified limits. (5) IVH (VH bias current) is positive, and I VL (VL bias current) is negative, under these conditions. See Note 3, Figure 1 and Figure 8 . (6) Limiter feedthrough is the ratio of the output magnitude to the sinewave added to V H (or VL) when VIN = 0. (7) VH slew rate conditions are: VIN = +2V, G = +2, VL = –2V, VH = step between 2V and 0V. VL slew rate conditions are similar. (8) Linearity Guardband is defined for an output sinusoid (f = 5MHz, VO = 0VDC ±1Vp-p) centered between the limiter levels (VH and VL). It is the difference between the limiter level and the peak output voltage where SFDR decreases by 3dB (see Figure 9). SPECIFICATIONS — VS = +5V G = +2, RL = 500Ω tied to VCM = 2.5V, RF = 402Ω, VL = VCM –1.2V, VH = VCM +1.2V (Figure 2 for AC performance only), unless otherwise noted. OPA688U, P TYP +25°C +25°C GUARANTEED(1) 0°C to +70°C –40°C to +85°C MIN/ TEST MAX LEVEL(2) PARAMETER AC PERFORMANCE (see Figure 2) Small Signal Bandwidth CONDITIONS UNITS Gain-Bandwidth Product (G ≥ +5) Gain Peaking 0.1dB Gain Flatness Bandwidth Large Signal Bandwidth Step Response: Slew Rate Rise/Fall Time Settling Time: 0.05% Spurious Free Dynamic Range Input Noise: Voltage Noise Density Current Noise Density DC PERFORMANCE Open Loop Voltage Gain (AOL) Input Offset Voltage Average Drift Input Bias Current(3) Average Drift Input Offset Current Average Drift VO < 0.2Vp-p G = +1, RF = 25Ω G = +2 G = –1 VO < 0.2Vp-p G = +1, RF = 25Ω, VO < 0.2Vp-p VO < 0.2Vp-p VO = 2Vp-p 2V Step 0.2V Step 1V Step f = 5MHz, VO = 2Vp-p f ≥ 1MHz f ≥ 1MHz VCM = 2.5V VO = ±0.5V 515 240 190 275 10 50 240 1000 2.3 12 64 6.3 2.0 52 ±2 — +6 — ±0.3 — — 110 — 130 — — 110 800 2.6 — 60 7.2 2.5 46 — — 105 — 125 — — 105 770 2.7 — 56 7.8 2.9 44 ±7 ±14 ±13 –60 ±3 ±10 — 100 — 120 — — 100 650 3 — 51 8 3.6 43 ±9 ±14 ±20 –90 ±4 ±10 MHz MHz MHz MHz dB MHz MHz V/µs ns ns dB nV/√Hz pA/√Hz dB mV µV/°C µA nA/°C µA nA/°C Typ Min Typ Min Typ Typ Min Min Max Typ Min Max Max Min Max Max Max Max Max Max C B C B C C B B B C B B B A A B A B A B ±6 — ±12 ±2 — ® 3 OPA688 SPECIFICATIONS— VS = +5V (CONT) OPA688U, P TYP +25°C 55 VCM ±0.8 0.4 || 1 1 || 1 +25°C 48 VCM ±0.7 — — VCM ±1.4 60 –50 — — +12 15 11 — VCM ±0.6 200 VCM ±1.8 65 0 — — — GUARANTEED(1) 0°C to +70°C 47 VCM ±0.7 — — VCM ±1.4 55 –45 — — +12 15 10 — VCM ±0.6 200 VCM ±1.8 75 0 30 — — ±40 — — — — — — — — — –40°C to +85°C 45 VCM ±0.6 — — VCM ±1.3 50 –40 — — +12 16 9 — VCM ±0.6 200 VCM ±1.8 85 0 50 — — ±40 — — — — — — — — — MIN/ TEST MAX LEVEL(2) G = +2, RL = 500Ω tied to VCM = 2.5V, RF = 402Ω, VL = –1.2V, VH = +1.2V (Figure 2 for AC performance only), unless otherwise noted. PARAMETER INPUT Common-Mode Rejection Common-Mode Input Range(4) Input Impedance Differential-Mode Common-Mode OUTPUT Output Voltage Range Current Output, Sourcing Sinking Closed-Loop Output Impedance POWER SUPPLY Operating Voltage, Specified Maximum Quiescent Current, Maximum Minimum Power Supply Rejection Ratio +PSR (Input Referred) OUTPUT VOLTAGE LIMITERS Default Limiter Voltage Minimum Limiter Separation (VH – VL) Maximum Limit Voltage Limiter Input Bias Current Magnitude(5) Maximum Minimum Average Drift Limiter Input Impedance Limiter Feedthrough(6) DC Performance in Limit Mode Limiter Voltage Accuracy Op Amp Bias Current Shift(3) AC Performance in Limit Mode Limiter Small Signal Bandwidth Limiter Slew Rate(7) Limited Step Response Overshoot Recovery Time Linearity Guardband(8) THERMAL CHARACTERISTICS Temperature Range Thermal Resistance P 8-Pin DIP U 8-Pin SO-8 CONDITIONS Input Referred, VCM = ±0.5V UNITS dB V MΩ || pF MΩ || pF V mA mA Ω V V mA mA dB V mV V µA µA nA/°C MΩ || pF dB mV µA MHz V/µs mV ns mV °C °C/W °C/W Min Min Typ Typ Min Min Min Typ Typ Max Max Min Typ Min Min Max Max Min Max Typ Typ Max Typ Typ Typ Typ Max Max Typ Typ Typ A A C C A A A C C A A A C A B B A A B C C A C C C C C C C C C VH = VCM +1.8V, VL = = VCM –1.8V RL ≥ 500Ω VO = 2.5V VO = 2.5V G = +1, RF = 25Ω, f < 100kHz Single Supply Operation VCM ±1.6 70 –60 0.2 +5 — 13 13 VS = 4.5V to 5.5V 65 Pins 5 and 8 Limiter Pins Open VCM ±0.9 200 — 35 35 — 2 || 1 –60 ±15 5 300 20 55 15 30 –40 to +85 100 125 VO = 2.5V f = 5MHz VIN = VCM ±1.2V (VO – VH) or (VO – VL) VIN = VCM ±1.2V, VO < 0.02Vp-p 2x Overdrive VIN = VCM to VCM ±1.2V Step VIN = VCM ±1.2V to VCM Step f = 5MHz, VO = 2Vp-p Specification: P, U Junction-to-Ambient ±35 — — — — — — — — — NOTES: (1) Junction Temperature = Ambient Temperature for low temperature limit and 25 °C guaranteed specifications. Junction Temperature = Ambient Temperature + 23°C at high temperature limit guaranteed specifications. (2) TEST LEVELS: (A) 100% tested at 25 °C. Over temperature limits by characterization and simulation. (B) Limits set by characterization and simulation. (C) Typical value for information only. (3) Current is considered positive out of node. (4) CMIR tested as < 3dB degradation from minimum CMRR at specified limits. (5) I VH (VH bias current) is negative, and I VL (VL bias current) is positive, under these conditions. See Note 3, Figures 2, and Figure 8. (6) Limiter feedthrough is the ratio of the output magnitude to the sinewave added to V H (or VL) when VIN = 0. (7) VH slew rate conditions are: V IN = VCM +0.4V, G = +2, V L = VCM –1.2V, VH = step between V CM + 1.2V and VCM. VL slew rate conditions are similar. (8) Linearity Guardband is defined for an output sinusoid (f = 5MHz, V O = VCM ±1Vp-p) centered between the limiter levels (V H and VL). It is the difference between the limiter level and the peak output voltage where SFDR decreases by 3dB (see Figure 9). ® OPA688 4 ABSOLUTE MAXIMUM RATINGS Supply Voltage ................................................................................. ±6.5V Internal Power Dissipation .......................... See Thermal Characteristics Common-Mode Input Voltage ............................................................. ±VS Differential Input Voltage ..................................................................... ±VS Limiter Voltage Range ........................................................... ±(VS – 0.7V) Storage Temperature Range: P, U ................................ –40°C to +125°C Lead Temperature (DIP, soldering, 10s) ..................................... +300°C (SO-8, soldering, 3s) ...................................... +260°C Junction Temperature .................................................................... +175°C ELECTROSTATIC DISCHARGE SENSITIVITY Electrostatic discharge can cause damage ranging from performance degradation to complete device failure. Burr-Brown Corporation recommends that all integrated circuits be handled and stored using appropriate ESD protection methods. 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 published specifications. PIN CONFIGURATION Top View DIP-8, SO-8 NC Inverting Input Non-Inverting Input –VS 1 2 3 4 8 7 6 5 VH +VS Output VL PACKAGE/ORDERING INFORMATION PACKAGE DRAWING NUMBER 006 182 SPECIFIED TEMPERATURE RANGE –40°C to +85°C –40°C to +85°C PACKAGE MARKING OPA688P OPA688U ORDERING NUMBER(1) OPA688P OPA688U OPA688U/2K5 TRANSPORT MEDIA Rails Rails Tape and Reel PRODUCT OPA688P OPA688U PACKAGE DIP-8 Plastic DIP SO-8 Surface Mount " " " " " NOTES: (1) Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /2K5 indicates 2500 devices per reel). Ordering 2500 pieces of OPA688U/2K5” will get a single 2500-piece Tape and Reel. The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant any BURR-BROWN product for use in life support devices and/or systems. ® 5 OPA688 TYPICAL PERFORMANCE CURVES —VS = ±5V G = +2, RL = 500Ω, RF = 402Ω, VH = –VL = 2V (Figure 1 for AC performance only), unless otherwise noted. NON-INVERTING SMALL-SIGNAL FREQUENCY RESPONSE 12 9 VO = 0.2Vp-p G = +1, RC = ∞, RF = 25Ω INVERTING SMALL-SIGNAL FREQUENCY RESPONSE 6 3 Normalized Gain (dB) VO = 0.2Vp-p G = –1 Normalized Gain (dB) 6 3 0 –3 –6 –9 –12 –15 –18 1M VIN RS 150Ω G = +1, RC = 175Ω, RF = 25Ω G = +2, RC = ∞ 0 –3 –6 –9 –12 –15 –18 G = –2 VO RC RF RG G = –5 G = +5, RC = ∞ 100M Frequency (Hz) 1G –21 –24 1M 10M 100M Frequency (Hz) 1G 10M SMALL-SIGNAL PULSE RESPONSE 0.25 0.20 0.15 Output Voltage (V) Output Voltage (V) LARGE-SIGNAL PULSE RESPONSE 2.5 2.0 1.5 0.10 0.05 0 –0.5 –1.0 –1.5 –2.0 –2.5 VO = 4Vp-p VH = –VL = 2.5V VO = 0.2Vp-p 0.10 0.05 0 –0.05 –0.10 –0.15 –0.20 –0.25 Time (5ns/div) Time (5ns/div) VH—LIMITED PULSE RESPONSE 2.5 Input and Output Voltages (V) Input and Output Voltages (V) VL—LIMITED PULSE RESPONSE 2.5 2.0 1.5 1.0 0.5 0 –0.5 –1.0 –1.5 –2.0 –2.5 VIN VO G = +2 VL = –2V 2.0 1.5 1.0 0.5 0 –0.5 –1.0 –1.5 –2.0 –2.5 Time (20ns/div) G = +2 VH = +2V VIN VO Time (20ns/div) ® OPA688 6 TYPICAL PERFORMANCE CURVES —VS = ±5V G = +2, RL = 500Ω, RF = 402Ω, VH = –VL = 2V (Figure 1 for AC performance only), unless otherwise noted. (cont.) HARMONIC DISTORTION vs FREQUENCY 2nd and 3rd Harmonic Distortion (dBc) HARMONIC DISTORTION NEAR LIMIT VOLTAGES 2nd and 3rd Harmonic Distortion (dBc) –40 –45 –50 –55 –60 –65 –70 –75 –80 –85 –90 1M Frequency (Hz) 10M 20M HD3 HD2 VO = 2Vp-p RL = 500Ω –40 –45 –50 –55 –60 –65 –70 –75 –80 –85 –90 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 HD3 HD2 VO = 0VDC ±1Vp f1 = 5MHz RL = 500Ω ± Limit Voltage (V) 2ND HARMONIC DISTORTION vs OUTPUT SWING –40 3RD HARMONIC DISTORTION vs OUTPUT SWING –40 –45 RL = 500Ω 2nd Harmonic Distortion (dBc) –50 –55 –60 –65 –70 –75 –80 –85 –90 0.1 1.0 Output Swing (Vp-p) f1 = 10MHz f1 = 20MHz 3rd Harmonic Distortion (dBc) –45 RL = 500Ω –50 –55 –60 –65 –70 –75 –80 –85 –90 f1 = 2MHz f1 = 5MHz f1 = 10MHz f1 = 20MHz f1 = 1MHz f1 = 5MHz f1 = 2MHz f1 = 1MHz 5.0 0.1 1.0 Output Swing (Vp-p) 5.0 HARMONIC DISTORTION vs LOAD RESISTANCE 2nd and 3rd Harmonic Distortion (dBc) –40 –45 –50 –55 –60 –65 –70 –75 –80 –85 –90 50 100 Load Resistance (Ω) 1000 HD3 HD2 Gain (dB) 12 LARGE-SIGNAL FREQUENCY RESPONSE 9 6 3 0 –3 –6 –9 –12 –15 –18 1M 10M 100M Frequency (Hz) 1G 2Vp-p G = +2 ≤ 0.2Vp-p VO = 2Vp-p f1 = 5MHz ® 7 OPA688 TYPICAL PERFORMANCE CURVES —VS = ±5V G = +2, RL = 500Ω, RF = 402Ω, VH = –VL = 2V (Figure 1 for AC performance only), unless otherwise noted. (cont.) RS vs CAPACITIVE LOAD 80 Gain to Capacitive Load (dB) 12 9 6 3 0 –3 –6 –9 –12 VIN FREQUENCY RESPONSE vs CAPACITIVE LOAD VO = 0.2Vp-p CL = 0 CL = 10pF CL = 100pF 200Ω RS 70 60 50 RS ( Ω ) 40 30 20 10 0 1 10 100 300 Capacitive Load (pF) OPA688 402Ω 402Ω 1kΩ VO CL –15 –18 1M 1kΩ is optional 10M 100M Frequency (Hz) 1G OPEN-LOOP FREQUENCY RESPONSE Input Voltage Noise Density (nV/√Hz) Input Current Noise Density (pA/√Hz) INPUT NOISE DENSITY 0 60 50 Gain 100 –30 –60 –90 Open-Loop Gain (dB) 40 30 20 10 0 –10 –20 10k Open-Loop Phase (deg) Phase Voltage Noise 10 Current Noise 6.3nV/√Hz VO = 0.2Vp-p –120 –150 –180 –210 –240 1G 2.0pA/√Hz 1 100 1k 10k 100k 1M 10M Frequency (Hz) 100k 1M 10M 100M Frequency (Hz) LIMITER SMALL-SIGNAL FREQUENCY RESPONSE 6 3 0 VO = 0.02Vp-p –30 –35 –40 LIMITER FEEDTHROUGH –6 –9 –12 –15 –18 –21 –24 1M 200Ω 2VDC Feedthrough (dB) Limiter Gain (dB) –3 VH = 0.02Vp-p + 2.0VDC 8 VO 402Ω 402Ω –45 –50 –55 –60 –65 –70 –75 –80 402Ω 402Ω 200Ω 8 VO VH = 0.02Vp-p + 2VDC 10M 100M Frequency (Hz) 1G 1M 10M Frequency (Hz) 50M ® OPA688 8 TYPICAL PERFORMANCE CURVES —VS = ±5V G = +2, RL = 500Ω, RF = 402Ω, VH = –VL = 2V (Figure 1 for AC performance only), unless otherwise noted. (cont.) CLOSED-LOOP OUTPUT IMPEDANCE 100 Limter Input Bias Current (µA) 100 LIMITER INPUT BIAS CURRENT vs BIAS VOLTAGE Maximum Over Temperature 75 50 25 0 –25 –50 –75 Limiter Headroom = +VS – VH = VL – (–VS) Current = IVH or –IVL 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Minimum Over Temperature Output Impedance (Ω) G = +1 RF = 25Ω VO = 0.2Vp-p 10 1 0.1 1M 10M 100M 1G Frequency (Hz) –100 Limiter Headroom (V) SUPPLY AND OUTPUT CURRENTS vs TEMPERATURE 20 120 100 PSR AND CMR vs TEMPERATURE PSR and CMR, Input Referred (dB) 95 90 85 80 75 70 65 60 55 50 –50 –25 0 25 50 75 100 Ambient Temperature (°C) CMRR PSR+ PSRR PSR– 18 Output Current, Sourcing 110 Supply Current (mA) 16 Supply Current 100 14 | Output Current, Sinking | 12 90 80 10 –50 –25 0 25 50 75 Ambient Temperature (°C) 70 100 VOLTAGE RANGES vs TEMPERATURE 5.0 VH = –VL = 4.3V 4.5 Output Voltage Range 4.0 ±Voltage Range (V) 3.5 Common-Mode Input Range 3.0 –50 –25 0 25 50 75 100 Ambient Temperature (°C) Output Current (mA) ® 9 OPA688 TYPICAL PERFORMANCE CURVES —VS = +5V G = +2, RF = 402Ω, RL = 500Ω tied to VCM = 2.5V, VL = VCM –1.2V, VH = VCM +1.2V, (Figure 2 for AC performance only), unless otherwise noted. NON-INVERTING SMALL-SIGNAL FREQUENCY RESPONSE 12 9 Normalized Gain (dB) INVERTING SMALL-SIGNAL FREQUENCY RESPONSE 6 3 Normalized Gain (dB) VO = 0.2Vp-p G = +1, RC = ∞, RF = 25Ω G = +1, RC = 175Ω, RF = 25Ω G = +2, RC = ∞ VO = 0.2Vp-p G = –1 G = –2 G = –5 6 3 0 –3 –6 –9 –12 –15 –18 1M VIN RS 150Ω 0 –3 –6 –9 –12 –15 –18 VO RC RF RG G = +5, RC = ∞ 10M 100M Frequency (Hz) 1G –21 –24 1M 10M 100M Frequency (Hz) 1G LARGE-SIGNAL FREQUENCY RESPONSE 12.0 9.0 6.0 3.0 Input and Output Voltages (V) VH AND VL—LIMITED PULSE RESPONSE 5.0 4.5 VH = VCM +1.2V VL = VCM –1.2V G = +2 ≤ 0.2Vp-p 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 VCM = 2.5V VIN VO Gain (dB) 0 –3.0 –6.0 –9.0 –12.0 –15.0 –18.0 1M 10M 100M Frequency (Hz) 1G 2.0Vp-p VIN VO Time (20ns/div) HARMONIC DISTORTION vs FREQUENCY HARMONIC DISTORTION NEAR LIMIT VOLTAGES 2nd and 3rd Harmonic Distortion (dBc) 2nd and 3rd Harmonic Distortion (dBc) –40 –45 –50 –55 –60 –65 –70 –75 –80 –85 –90 1M Frequency (Hz) 10M 20M HD3 HD2 VO = 2Vp-p RL = 500Ω –40 –45 –50 –55 –60 –65 –70 –75 –80 –85 –90 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 HD3 HD2 VO = 2.5V ±1Vp f1 = 5MHz RL = 500Ω | Limit Voltages – 2.5VDC | ® OPA688 10 TYPICAL APPLICATIONS DUAL SUPPLY, NON-INVERTING AMPLIFIER Figure 1 shows a non-inverting gain amplifier for dual supply operation. This circuit was used for AC characterization of the OPA688, with a 50Ω source, which it matches, and a 500Ω load. The power supply bypass capacitors are shown explicitly in Figures 1 and 2, but will be assumed in the other figures. The limiter voltages (VH and VL) and their bias currents (IVH and IVL) have the polarities shown. SINGLE SUPPLY, NON-INVERTING AMPLIFIER Figure 2 shows an AC coupled, non-inverting gain amplifier for single supply operation. This circuit was used for AC characterization of the OPA688, with a 50Ω source, which 3.01kΩ +VS = +5V + 2.2µF 0.1µF 0.1µF VH = +2V 174Ω VIN 49.9Ω 2 RG 402Ω RF 402Ω 4 3 7 8 1.91kΩ it matches, and a 500Ω load. The power supply bypass capacitors are shown explicitly in Figures 1 and 2, but will be assumed in the other figures. The limiter voltages (VH and VL) and their bias currents (IVH and IVL) have the polarities shown. Notice that the single supply circuit can use 3 resistors to set VH and VL, where the dual supply circuit usually uses 4 to reference the limit voltages to ground. LIMITED OUTPUT, ADC INPUT DRIVER Figure 3 shows a simple ADC driver that operates on single supply, and gives excellent distortion performance. The limit voltages track the input range of the converter, completely protecting against input overdrive. VS = +5V + 2.2µF 0.1µF 0.1µF 523Ω VH = 3.7V IVH 0.1µF 806Ω OPA688 5 6 IVL 500Ω VO 3 806Ω 2 7 8 IVH 6 IVL VIN 57.6Ω 976Ω 0.1µF VO 500Ω OPA688 5 4 0.1µF 0.1µF VL = –2V RF 402Ω 0.1µF RG 402Ω VL = 1.3V 523Ω + –VS = –5V 2.2µF 3.01kΩ 1.91kΩ 0.1µF FIGURE 1. DC-Coupled, Dual Supply Amplifier. FIGURE 2. AC-Coupled, Single Supply Amplifier. VS = +5V 562Ω VH = +3.6V 0.1µF 715Ω 0.1µF VIN 3 VS = +5V 7 8 OPA688 2 715Ω 4 REFB 402Ω +1.5V 102Ω 402Ω 0.1µF VL = +1.4V 0.1µF 562Ω INT/EXT GND 5 6 24.9Ω IN 100pF ADS822 10-Bit 40MSPS 10-Bit Data 102Ω +3.5V REFT RSEL +VS VS = +5V FIGURE 3. Single Supply, Limiting ADC Input Driver. ® 11 OPA688 PRECISION HALF WAVE RECTIFIER Figure 4 shows a half wave rectifier with outstanding precision and speed. VH (pin 8) will default to a voltage between 3.1 and 3.8V if left open, while the negative limit is set to ground. When VO tries to go below ground, CCII charges C1 through D1, which restores the output back to ground. D1 adds a propagation delay to the restoration process, which then has an exponential decay with time constant R1C1/G (G = +2 = the OPA688 gain). When the signal is above ground, it decays to ground with a time constant of R2C1. The OPA688 output recovers very quickly from overdrive. +VS = +5V 200Ω VIN 2 7 NC 8 6 3.01kΩ +VS = +5V VO 1.91kΩ OPA688 3 4 402Ω 402Ω 5 0.1µF 200Ω VIN 402Ω VO 3 7 8 133Ω 6 –VS = –5V FIGURE 4. Precision Half Wave Rectifier. VERY HIGH SPEED SCHMITT TRIGGER Figure 5 shows a very high speed Schmitt trigger. The output levels are precisely defined, and the switching time is exceptional. The output voltage swings between ±2V. –VS = –5V 2 4 OPA688 5 0.1µF 3.01kΩ 1.91kΩ UNITY-GAIN BUFFER Figure 6 shows a unity-gain voltage buffer using the OPA688. The feedback resistor (RF) isolates the output from any board inductance between pins 2 and 6. We recommend that RF ≥ 24.9Ω for unity-gain buffer applications. RC is an optional compensation resistor that reduces the peaking typically seen at G = +1. Choosing RC = RS + RF gives a unity gain buffer with approximately the G = +2 frequency response. DC RESTORER Figure 7 shows a DC restorer using the OPA688 and OPA660. The OPA660’s OTA amplifier is used as a current conveyor (CCII) in this circuit, with a current gain of 1.0. FIGURE 5. Very High Speed Schmitt Trigger. RS VS RC OPA688 VO RF 24.9Ω FIGURE 6. Unity-Gain Buffer. U1 200Ω VIN 5 +1 1 U1 = OPA660 RQ = 1kΩ (sets U1’s IQ) D1, D2 = 1N4148 RQ 1kΩ 6 C1 100pF 20Ω D1 VH = +3V 8 R2 100kΩ OPA688 5 VL = –1V 402Ω VO D2 20Ω 3 B C CCII U1 402Ω 2 R1 40.2Ω E FIGURE 7. DC Restorer. ® OPA688 12 DESIGN-IN TOOLS APPLICATIONS SUPPORT The Burr-Brown Applications Department is available for design assistance at 1-800-548-6132 (US/Canada only). The Burr-Brown Internet web page (http://www.burr-brown.com) has the latest data sheets and other design aids. DEMONSTRATION BOARDS Two PC boards are available to assist in the initial evaluation of circuit performance of the OPA688 in both package styles. These are available as an unpopulated PCB with descriptive documentation. See the demonstration board literature for more information. The summary information for these boards is shown below: LITERATURE REQUEST NUMBER MKT-350 MKT-351 The limiters have a very sharp transition from the linear region of operation to output limiting. This allows the limiter voltages to be set very near (