LMH6551QMM/NOPB

LMH6551Q www.ti.com SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 LMH6551Q Differential, High Speed Op Amp Check for Samples: LMH6551Q FEATURES 1 • • • • • • 23 370 MHz −3 dB Bandwidth (VOUT = 0.5 VPP) 50 MHz 0.1 dB Bandwidth 2400 V/µs Slew Rate 18 ns Settling Time to 0.05% −94/−96 dB HD2/HD3 @ 5 MHz LMH6551Q is AEC-Q100 Grade 1 Qualified and is Manufactured on an Automotive Grade Flow APPLICATIONS • • • • • • • • Differential AD Driver Video Over Twisted Pair Differential Line Driver Single End to Differential Converter High Speed Differential Signaling IF/RF Amplifier SAW Filter Buffer/Driver Automotive DESCRIPTION The LMH™6551Q is a high performance voltage feedback differential amplifier. The LMH6551Q has the high speed and low distortion necessary for driving high performance ADCs as well as the current handling capability to drive signals over balanced transmission lines like CAT 5 data cables. The LMH6551Q can handle a wide range of video and data formats. With external gain set resistors, the LMH6551Q can be used at any desired gain. Gain flexibility coupled with high speed makes the LMH6551Q suitable for use as an IF amplifier in high performance communications equipment. The LMH6551Q is available in the VSSOP package. Typical Application 1 2 3 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. LMH is a trademark of Texas Instruments. All other 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 © 2011–2013, Texas Instruments Incorporated LMH6551Q SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 www.ti.com Connection Diagram -IN VCM V+ +OUT 1 2 8 - + 7 3 6 4 5 +IN NC V- -OUT Figure 1. Top View 8-Pin VSSOP See Package Number DGK These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Absolute Maximum Ratings ESD Tolerance (1) (2) (3) Human Body Model Machine Model Supply Voltage 2000V 200V 13.2V Common Mode Input Voltage ±Vs Maximum Input Current (pins 1, 2, 7, 8) 30mA (4) Maximum Output Current (pins 4, 5) Maximum Junction Temperature 150°C Soldering Information: http://www.ti.com/lit/SNOA549 (1) (2) (3) (4) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not ensured. For ensured specifications, see the Electrical Characteristics tables. If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications. Human body model: 1.5 kΩ in series with 100 pF. Machine model: 0Ω in series with 200pF. The maximum output current (IOUT) is determined by device power dissipation limitations. Operating Ratings (1) Operating Temperature Range −40°C to +125°C Storage Temperature Range −65°C to +150°C Total Supply Voltage Package Thermal Resistance (θJA) 3V to 11V (2) 8-Pin VSSOP (1) (2) 2 159°C/W Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not ensured. For ensured specifications, see the Electrical Characteristics tables. The maximum power dissipation is a function of TJ(MAX), θJA and TA. The maximum allowable power dissipation at any ambient temperature is P D= (TJ(MAX) — TA)/ θJA. All numbers apply for package soldered directly into a 4 layer PC board with zero air flow. Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Product Folder Links: LMH6551Q LMH6551Q www.ti.com SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 ±5V Electrical Characteristics (1) Single ended in differential out, TA= 25°C, G = +1, VS = ±5V, VCM = 0V, RF = RG = 365Ω, RL = 500Ω; Unless specified Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min (2) Typ (3) Max (2) Units AC Performance (Differential) SSBW Small Signal −3 dB Bandwidth VOUT = 0.5 VPP 370 MHz LSBW Large Signal −3 dB Bandwidth VOUT = 2 VPP 340 MHz Large Signal −3 dB Bandwidth VOUT = 4 VPP 320 MHz 0.1 dB Bandwidth VOUT = 2 VPP 50 MHz (4) Slew Rate 4V Step 2400 V/μs Rise/Fall Time 2V Step 1.8 ns Settling Time 2V Step, 0.05% 18 ns VCMbypass capacitor removed 200 MHz HD2 VO = 2 VPP, f = 5 MHz, RL=800Ω −94 dBc HD2 VO = 2 VPP, f = 20MHz, RL=800Ω −85 dBc HD3 VO = 2 VPP, f = 5 MHz, RL=800Ω −96 dBc VCM Pin AC Performance (Common Mode Feedback Amplifier) Common Mode Small Signal Bandwidth Distortion and Noise Response VO = 2 VPP, f = 20 MHz, RL=800Ω −72 dBc en Input Referred Voltage Noise Freq ≥ 1 MHz 6.0 nV/√Hz in Input Referred Noise Current Freq ≥ 1 MHz 1.5 pA/√Hz Differential Mode, VID = 0, VCM = 0 0.5 HD3 Input Characteristics (Differential) VOSD IBI Input Offset Voltage ±4 ±6 mV Input Offset Voltage Average Temperature Drift (5) −0.8 Input Bias Current (6) -4 Input Bias Current Average Temperature Drift (5) −2.6 nA/°C 0.03 µA µV/°C 0 -10 µA Input Bias Difference Difference in Bias currents between the two inputs CMRR Common Mode Rejection Ratio DC, VCM = 0V, VID = 0V 80 dBc RIN Input Resistance Differential 5 MΩ CIN Input Capacitance Differential 1 pF CMVR Input Common Mode Voltage Range CMRR > 53dB +3.2 −4.7 V (1) (2) (3) (4) (5) (6) 70 +3.1 −4.6 Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating of the device such that TJ = TA. No specification of parametric performance is indicated in the electrical tables under conditions of internal self-heating where TJ > TA. Limits are 100% production tested at 25°C. Limits over the operating temperature range are ensured through correlation using Statistical Quality Control (SQC) methods. Typical numbers are the most likely parametric norm. Slew Rate is the average of the rising and falling edges. Drift determined by dividing the change in parameter at temperature extremes by the total temperature change. Negative input current implies current flowing out of the device. Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Product Folder Links: LMH6551Q 3 LMH6551Q SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 www.ti.com ±5V Electrical Characteristics (1) (continued) Single ended in differential out, TA= 25°C, G = +1, VS = ±5V, VCM = 0V, RF = RG = 365Ω, RL = 500Ω; Unless specified Boldface limits apply at the temperature extremes. Symbol Parameter Min (2) Conditions Typ (3) Max (2) Units 0.5 ±5 ±8 mV VCMPin Input Characteristics (Common Mode Feedback Amplifier) VOSC Input Offset Voltage Common Mode, VID = 0 Input Offset Voltage Average Temperature Drift (7) Input Bias Current (8) VCM CMRR 8.2 µV/°C −2 μA 70 75 dB ΔVO,CM/ΔVCM 0.995 0.999 Single Ended, Peak to Peak ±7.38 ±7.18 ±7.8 ±3.69 ±3.8 V ±50 ±65 mA VID = 0V, 1V step on VCM pin, measure VOD Input Resistance 25 Common Mode Gain kΩ 1.005 V/V Output Performance Output Voltage Swing Output Common Mode Voltage Range VID = 0 V, V IOUT Linear Output Current VOUT = 0V ISC Short Circuit Current Output Shorted to Ground VIN = 3V Single Ended (9)l 140 mA Output Balance Error ΔVOUTCommon Mode /ΔVOUTDIfferential, VOUT = 0.5 Vpp Differential, f = 10 MHz −70 dB 70 dB Miscellaneous Performance AVOL Open Loop Gain Differential PSRR Power Supply Rejection Ratio DC, ΔVS = ±1V 71 90 Supply Current RL = ∞ 11 12.5 (7) (8) (9) dB 14.5 16.5 mA Drift determined by dividing the change in parameter at temperature extremes by the total temperature change. Negative input current implies current flowing out of the device. The maximum output current (IOUT) is determined by device power dissipation limitations. 5V Electrical Characteristics (1) Single ended in differential out, TA= 25°C, G = +1, VS = 5V, VCM = 2.5V, RF = RG = 365Ω, RL = 500Ω; Unless specified Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min (2) Typ (3) Max (2) Units SSBW Small Signal −3 dB Bandwidth RL = 500Ω, VOUT = 0.5 VPP 350 MHz LSBW Large Signal −3 dB Bandwidth RL = 500Ω, VOUT = 2 VPP 300 MHz 0.1 dB Bandwidth VOUT = 2 VPP 50 MHz Slew Rate 4V Step (4) 1800 V/μs Rise/Fall Time, 10% to 90% 4V Step 2 ns Settling Time 4V Step, 0.05% 17 ns 170 MHz VCM Pin AC Performance (Common Mode Feedback Amplifier) Common Mode Small Signal Bandwidth (1) (2) (3) (4) 4 Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating of the device such that TJ = TA. No specification of parametric performance is indicated in the electrical tables under conditions of internal self-heating where TJ > TA. Limits are 100% production tested at 25°C. Limits over the operating temperature range are ensured through correlation using Statistical Quality Control (SQC) methods. Typical numbers are the most likely parametric norm. Slew Rate is the average of the rising and falling edges. Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Product Folder Links: LMH6551Q LMH6551Q www.ti.com SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 5V Electrical Characteristics (1) (continued) Single ended in differential out, TA= 25°C, G = +1, VS = 5V, VCM = 2.5V, RF = RG = 365Ω, RL = 500Ω; Unless specified Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min (2) Typ (3) Max (2) Units Distortion and Noise Response HD2 2nd Harmonic Distortion HD2 HD3 3rd Harmonic Distortion HD3 VO = 2 VPP, f = 5 MHz, RL=800Ω −84 dBc VO = 2 VPP, f = 20 MHz, RL=800Ω −69 dBc VO = 2 VPP, f = 5 MHz, RL=800Ω −93 dBc VO = 2 VPP, f = 20 MHz, RL=800Ω −67 dBc en Input Referred Noise Voltage Freq ≥ 1 MHz 6.0 nV/√Hz in Input Referred Noise Current Freq ≥ 1 MHz 1.5 pA/√Hz Differential Mode, VID = 0, VCM = 0 0.5 Input Characteristics (Differential) VOSD IBIAS CMRR VICM Input Offset Voltage ±4 ±6 mV Input Offset Voltage Average Temperature Drift (5) −0.8 Input Bias Current (6) −4 Input Bias Current Average Temperature Drift (5) −3 nA/°C 0.03 µA 78 dBc µV/°C μA 0 -10 Input Bias Current Difference Difference in Bias currents between the two inputs Common-Mode Rejection Ratio DC, VID = 0V Input Resistance Differential 5 MΩ Input Capacitance Differential 1 pF Input Common Mode Range CMRR > 53 dB 70 +3.1 +0.4 +3.2 +0.3 VCMPin Input Characteristics (Common Mode Feedback Amplifier) Input Offset Voltage Common Mode, VID = 0 0.5 Input Offset Voltage Average Temperature Drift ±5 ±8 mV 5.8 µV/°C 3 μA 70 75 dB Input Bias Current VCM CMRR VID = 0, 1V step on VCM pin, measure VOD Input Resistance VCM pin to ground Common Mode Gain ΔVO,CM/ΔVCM 0.995 0.999 ±2.8 V 25 kΩ 1.005 V/V Output Performance VOUT Output Voltage Swing Single Ended, Peak to Peak, VS= ±2.5V, VCM= 0V ±2.4 IOUT Linear Output Current VOUT = 0V Differential ±45 ISC Output Short Circuit Current Output Shorted to Ground VIN = 3V Single Ended (7) CMVR Output Common Mode Voltage Range VID = 0, VCMpin = 1.2V and 3.8V Output Balance Error ΔVOUTCommon Mode /ΔVOUTDIfferential, VOUT = 1Vpp Differential, f = 10 MHz 1.23 3.72 ±60 mA 230 mA 1.20 3.80 V −65 dB 70 dB Miscellaneous Performance Open Loop Gain DC, Differential PSRR Power Supply Rejection Ratio DC, ΔVS = ±0.5V 71 88 IS Supply Current RL = ∞ 10 11.5 (5) (6) (7) dB 13.5 15.5 mA Drift determined by dividing the change in parameter at temperature extremes by the total temperature change. Negative input current implies current flowing out of the device. The maximum output current (IOUT) is determined by device power dissipation limitations. Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Product Folder Links: LMH6551Q 5 LMH6551Q SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 3.3V Electrical Characteristics www.ti.com (1) Single ended in differential out, TA= 25°C, G = +1, VS = 3.3V, VCM = 1.65V, RF = RG = 365Ω, RL = 500Ω; Unless specified Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min (2) Typ (3) Max (2) Units SSBW Small Signal −3 dB Bandwidth RL = 500Ω, VOUT = 0.5 VPP 320 MHz LSBW Large Signal −3 dB Bandwidth RL = 500Ω, VOUT = 1 VPP 300 MHz Slew Rate 1V Step (4) 700 V/μs Rise/Fall Time, 10% to 90% 1V Step 2 ns 95 MHz VO = 1 VPP, f = 5 MHz, RL=800Ω −93 dBc VO = 1 VPP, f = 20 MHz, RL=800Ω −74 dBc VO = 1VPP, f = 5 MHz, RL=800Ω −85 dBc VO = 1VPP, f = 20 MHz, RL=800Ω −69 dBc VCM Pin AC Performance (Common Mode Feedback Amplifier) Common Mode Small Signal Bandwidth Distortion and Noise Response HD2 2nd Harmonic Distortion HD2 HD3 3rd Harmonic Distortion HD3 (1) (2) (3) (4) 6 Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating of the device such that TJ = TA. No specification of parametric performance is indicated in the electrical tables under conditions of internal self-heating where TJ > TA. Limits are 100% production tested at 25°C. Limits over the operating temperature range are ensured through correlation using Statistical Quality Control (SQC) methods. Typical numbers are the most likely parametric norm. Slew Rate is the average of the rising and falling edges. Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Product Folder Links: LMH6551Q LMH6551Q www.ti.com SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 3.3V Electrical Characteristics (1) (continued) Single ended in differential out, TA= 25°C, G = +1, VS = 3.3V, VCM = 1.65V, RF = RG = 365Ω, RL = 500Ω; Unless specified Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min (2) Typ (3) Max (2) Units Input Characteristics (Differential) VOSD IBIAS CMRR VICM Input Offset Voltage 1 mV Input Offset Voltage Average Temperature Drift Differential Mode, VID = 0, VCM = 0 (5) 1.6 µV/°C Input Bias Current (6) −8 μA Input Bias Current Average Temperature Drift (5) 9.5 nA/°C Input Bias Current Difference Difference in Bias currents between the two inputs 0.3 µA Common-Mode Rejection Ratio DC, VID = 0V 78 dBc Input Resistance Differential 5 MΩ Input Capacitance Differential 1 pF Input Common Mode Range CMRR > 53 dB +1.5 +0.3 VCMPin Input Characteristics (Common Mode Feedback Amplifier) Input Offset Voltage Common Mode, VID = 0 1 Input Offset Voltage Average Temperature Drift Input Bias Current ±5 mV 18.6 µV/°C 3 μA VCM CMRR VID = 0, 1V step on VCM pin, measure VOD 60 dB Input Resistance VCM pin to ground 25 kΩ Common Mode Gain ΔVO,CM/ΔVCM 0.999 V/V ±0.9 V Output Performance VOUT Output Voltage Swing Single Ended, Peak to Peak, VS= 3.3V, VCM= 1.65V ±0.75 IOUT Linear Output Current VOUT = 0V Differential ±40 mA ISC Output Short Circuit Current Output Shorted to Ground VIN = 2V Single Ended (7) 200 mA CMVR Output Common Mode Voltage Range VID = 0, VCMpin = 1.2V and 2.1V 2.1 1.2 V Output Balance Error ΔVOUTCommon Mode /ΔVOUTDIfferential, VOUT = 1Vpp Differential, f = 10 MHz −65 dB ±30 Miscellaneous Performance Open Loop Gain DC, Differential 70 dB PSRR Power Supply Rejection Ratio DC, ΔVS = ±0.5V 75 dB IS Supply Current RL = ∞ 8 mA (5) (6) (7) Drift determined by dividing the change in parameter at temperature extremes by the total temperature change. Negative input current implies current flowing out of the device. The maximum output current (IOUT) is determined by device power dissipation limitations. Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Product Folder Links: LMH6551Q 7 LMH6551Q SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics (TA = 25°C, VS = ±5V, RL = 500Ω, RF = RG = 365Ω; Unless Specified). Frequency Response vs. Supply Voltage 2 1 1 0 0 -1 -1 VOD = 2 VPP -2 -3 -4 -3 -6 -5 -6 SINGLE ENDED INPUT VS = ±5V -7 -8 1 10 100 1 1000 10 1000 FREQUENCY (MHz) Figure 2. Figure 3. Frequency Response vs. VOUT Frequency Response vs. Capacitive Load 2 2 1 1 CL = 5.7 pF, ROUT = 60: 0 0 -1 -1 CL = 10 pF, ROUT = 34: -2 CL = 27 pF, ROUT = 20: VOD = 1 VPP -2 -3 VOD = 0.5 VPP -4 -3 -4 -5 VS = ±5V CL = 57 pF, ROUT = 15: -5 LOAD = (CL || 1 k:) IN -6 -6 SERIES WITH 2 ROUTS SINGLE ENDED INPUT VS = 3.3V -7 -7 VOUT = 0.5 VPP DIFFERENTIAL -8 1 10 -8 1 10 100 1000 100 FREQUENCY (MHz) FREQUENCY (MHz) Figure 4. Figure 5. Suggested ROUT vs. Cap Load Suggested ROUT vs. Cap Load 70 60 60 SUGGESTED RO (:) 70 50 40 30 20 1000 50 LOAD = 1 k: || CAP LOAD 10 40 30 20 LOAD = 1 k: || CAP LOAD 10 VS = ±5V VS = 5V 0 0 1 8 100 FREQUENCY (MHz) GAIN (dB) GAIN (dB) SINGLE ENDED INPUT VS = 5V -7 -8 SUGGESTED RO (:) VOD = 0.5 VPP -4 VOD = 0.5 VPP -5 VOD = 2 VPP -2 GAIN (dB) GAIN (dB) Frequency Response 2 10 100 1 10 CAPACITIVE LOAD (pF) CAPACITIVE LOAD (pF) Figure 6. Figure 7. Submit Documentation Feedback 100 Copyright © 2011–2013, Texas Instruments Incorporated Product Folder Links: LMH6551Q LMH6551Q www.ti.com SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 Typical Performance Characteristics (continued) (TA = 25°C, VS = ±5V, RL = 500Ω, RF = RG = 365Ω; Unless Specified). 1 VPP Pulse Response Single Ended Input 2 VPP Pulse Response Single Ended Input 0.8 2.5 2 VOUT DIFFERENTIAL (V) VOUT DIFFERENTIAL (V) 0.6 0.4 0.2 0 -0.2 -0.4 VS = 3.3V RL = 500: -0.6 1.5 1 0.5 0 -0.5 -1 RL = 500: -2 RF = 360: RF = 360: -0.8 VS = 5V -1.5 -2.5 0 5 0 10 15 20 25 30 35 40 45 50 5 10 15 20 25 30 35 40 45 50 TIME (ns) TIME (ns) Figure 8. Figure 9. Large Signal Pulse Response Output Common Mode Pulse Response 3 0.12 VS = ±5V 0.1 COMMON MODE VOUT (V) VOUT DIFFERENTIAL (V) 2 1 0 -1 VS = ±5V RL = 500: -2 RF = 360: RF = 360: 0.06 VOUT = 4 VPP 0.04 0.02 0 -0.02 -0.04 -0.06 -3 -0.08 0 5 0 10 15 20 25 30 35 40 45 50 5 10 15 20 25 30 35 40 45 50 TIME (ns) TIME (ns) Figure 10. Figure 11. Distortion vs. Frequency Distortion vs. Frequency -50 -50 VS = ±5V VS = 5V HD3 DISTORTION (dBc) -60 RL = 800: -70 HD3 VOUT = 2 VPP -60 VOUT = 2 VPP VCM = 0V DISTORTION (dBc) RL = 500: 0.08 -80 -90 VCM = 2.5V RL = 800: -70 -80 HD2 HD2 -90 -100 -100 -110 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 FREQUENCY (MHz) FREQUENCY (MHz) Figure 12. Figure 13. Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Product Folder Links: LMH6551Q 9 LMH6551Q SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics (continued) (TA = 25°C, VS = ±5V, RL = 500Ω, RF = RG = 365Ω; Unless Specified). Distortion vs. Frequency Distortion vs. Supply Voltage (Split Supplies) -30 -50 VOUT = 2 VPP f = 5 MHz VS = 3.3V HD3 VOUT = 1 VPP VCM = VS/2 VCM = 1.65V -50 DISTORTION (dBc) DISTORTION (dBc) -60 -40 RL = 800: -70 -80 -60 -70 HD3 -80 HD2 -90 -90 HD2 -100 -100 0 5 10 15 20 25 30 35 3 40 4 FREQUENCY (MHz) Figure 14. Figure 15. Distortion vs. Supply Voltage (Single Supply) Maximum VOUT vs. IOUT 6 4 -65 VOUT = 4 VPP f = 5 MHz 3.9 VCM = 0V 3.8 -70 MAXIMUM VOUT (V) DISTORTION (dBc) -60 HD3 -75 -80 -85 HD2 -90 3.7 3.6 3.5 3.4 VIN = 3.88V SINGLE ENDED 3.3 VS = ±5V 3.2 -95 AV = 2 3.1 -100 RF = 730: 3 6 7 8 9 10 11 12 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 SUPPLY VOLTAGE (V) OUTPUT CURRENT (mA) Figure 16. Figure 17. Minimum VOUT vs. IOUT Closed Loop Output Impedance 100 -3 VIN = 3.88V SINGLE ENDED -3.1 VS = ±5V VIN = 0V VS = ±5V -3.2 AV = 2 -3.3 RF = 730: 10 -3.4 |Z| (:) MINIMUM VOUT (V) 5 SUPPLY VOLTAGE (V) -3.5 1 -3.6 -3.7 0.1 -3.8 -3.9 0.01 -4 0 10 20 30 40 50 60 70 80 90 100 0.1 1 10 100 1000 FREQUENCY (MHz) OUTPUT CURRENT (mA) Figure 18. 10 0.01 Figure 19. Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Product Folder Links: LMH6551Q LMH6551Q www.ti.com SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 Typical Performance Characteristics (continued) (TA = 25°C, VS = ±5V, RL = 500Ω, RF = RG = 365Ω; Unless Specified). Closed Loop Output Impedance Closed Loop Output Impedance 100 100 VS = 5V VS = 3.3V VIN = 0V VIN = 0V 10 |Z| (:) |Z| (:) 10 1 0.1 1 0.1 0.01 0.01 0.01 1 0.1 10 100 0.01 1000 1 0.1 Figure 20. Figure 21. PSRR PSRR 90 PSRR + PSRR (dBc DIFFERENTIAL) PSRR (dBc DIFFERENTIAL) 90 70 60 PSRR 50 40 VS = ±5V 20 RL = 200: 10 VCM = 0V 0 0.01 10 1 0.1 100 80 70 60 50 40 30 VS = +5V 20 RL = 200: 10 VCM = 2.5V 0 0.01 1000 1 0.1 10 100 FREQUENCY (MHz) FREQUENCY (MHz) Figure 22. Figure 23. CMRR 1000 Balance Error 80 -25 VS = ±5V -30 BALANCE ERROR (dBc) 75 70 CMRR (dB) 1000 100 80 65 60 55 50 45 100 FREQUENCY (MHz) 100 30 10 FREQUENCY (MHz) VIN, CM = 0.5 VPP 40 1 RL = 500: VIN = 0.5 VPP -55 -60 -65 -70 -75 -80 -85 -90 VS = ±5V 0.1 RF = 360: -35 -40 -45 -50 10 100 1000 1 10 100 FREQUENCY (MHz) FREQUENCY (MHz) Figure 24. Figure 25. 1000 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Product Folder Links: LMH6551Q 11 LMH6551Q SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 www.ti.com APPLICATION SECTION The LMH6551Q is a fully differential amplifier designed to provide low distortion amplification to wide bandwidth differential signals. The LMH6551Q, though fully integrated for ultimate balance and distortion performance, functionally provides three channels. Two of these channels are the V+ and V− signal path channels, which function similarly to inverting mode operational amplifiers and are the primary signal paths. The third channel is the common mode feedback circuit. This is the circuit that sets the output common mode as well as driving the V+ and V− outputs to be equal magnitude and opposite phase, even when only one of the two input channels is driven. The common mode feedback circuit allows single ended to differential operation. The LMH6551Q is a voltage feedback amplifier with gain set by external resistors. Output common mode voltage is set by the VCM pin. This pin should be driven by a low impedance reference and should be bypassed to ground with a 0.1 µF ceramic capacitor. Any signal coupling into the VCM will be passed along to the output and will reduce the dynamic range of the amplifier. FULLY DIFFERENTIAL OPERATION The LMH6551Q will perform best when used with split supplies and in a fully differential configuration. See Figure 26 and Figure 27 for recommended circuits. RF1 RO RG1 + VI a CL VCM RL VO RG2 RO RF2 Figure 26. Typical Application The circuit shown in Figure 26 is a typical fully differential application as might be used to drive an ADC. In this circuit closed loop gain, (AV) = VOUT/ VIN = RF/RG. For all the applications in this data sheet VIN is presumed to be the voltage presented to the circuit by the signal source. For differential signals this will be the difference of the signals on each input (which will be double the magnitude of each individual signal), while in single ended inputs it will just be the driven input signal. The resistors RO help keep the amplifier stable when presented with a load CL as is typical in an analog to digital converter (ADC). When fed with a differential signal, the LMH6551 provides excellent distortion, balance and common mode rejection provided the resistors RF, RG and RO are well matched and strict symmetry is observed in board layout. With a DC CMRR of over 80dB, the DC and low frequency CMRR of most circuits will be dominated by the external resistors and board trace resistance. At higher frequencies board layout symmetry becomes a factor as well. Precision resistors of at least 0.1% accuracy are recommended and careful board layout will also be required. 12 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Product Folder Links: LMH6551Q LMH6551Q www.ti.com SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 500 50: 100: TWISTED PAIR 250 + 2 VPP a VCM 250 2 VPP 50: 500 GAIN = 2 Figure 27. Fully Differential Cable Driver With up to 15 VPP differential output voltage swing and 80 mA of linear drive current the LMH6551Q makes an excellent cable driver as shown in Figure 27. The LMH6551Q is also suitable for driving differential cables from a single ended source. The LMH6551Q requires supply bypassing capacitors as shown in Figure 28 and Figure 29. The 0.01 µF and 0.1 µF capacitors should be leadless SMT ceramic capacitors and should be no more than 3 mm from the supply pins. The SMT capacitors should be connected directly to a ground plane. Thin traces or small vias will reduce the effectiveness of bypass capacitors. Also shown in both figures is a capacitor from the VCM pin to ground. The VCM pin is a high impedance input to a buffer which sets the output common mode voltage. Any noise on this input is transferred directly to the output. Output common mode noise will result in loss of dynamic range, degraded CMRR, degraded Balance and higher distortion. The VCM pin should be bypassed even if the pin in not used. There is an internal resistive divider on chip to set the output common mode voltage to the mid point of the supply pins. The impedance looking into this pin is approximately 25 kΩ. If a different output common mode voltage is desired drive this pin with a clean, accurate voltage reference. + V V + 0.01 PF 0.01 PF 10 PF 10 PF 0.01 PF + + VCM 0.1 PF 0.1 PF - VCM 0.1 PF 0.01 PF 10 PF V - Figure 28. Split Supply Bypassing Capacitors Figure 29. Single Supply Bypassing Capacitors Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Product Folder Links: LMH6551Q 13 LMH6551Q SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 www.ti.com SINGLE ENDED INPUT TO DIFFERENTIAL OUTPUT The LMH6551Q provides excellent performance as an active balun transformer. Figure 30 shows a typical application where an LMH6551Q is used to produce a differential signal from a single ended source. In single ended input operation the output common mode voltage is set by the VCM pin as in fully differential mode. Also, in this mode the common mode feedback circuit must recreate the signal that is not present on the unused differential input pin. Figure 25 is the measurement of the effectiveness of this process. The common mode feedback circuit is responsible for ensuring balanced output with a single ended input. Balance error is defined as the amount of input signal that couples into the output common mode. It is measured as a the undesired output common mode swing divided by the signal on the input. Balance error can be caused by either a channel to channel gain error, or phase error. Either condition will produce a common mode shift. Figure 25 measures the balance error with a single ended input as that is the most demanding mode of operation for the amplifier. Supply and VCM pin bypassing are also critical in this mode of operation. See the above section on FULLY DIFFERENTIAL OPERATION for bypassing recommendations and also see Figure 28 and Figure 29 for recommended supply bypassing configurations. Figure 30. Single Ended In to Differential Out 14 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Product Folder Links: LMH6551Q LMH6551Q www.ti.com SNOSB95E – NOVEMBER 2011 – REVISED MARCH 2013 SINGLE SUPPLY OPERATION The input stage of the LMH6551Q has a built in offset of 0.7V towards the lower supply to accommodate single supply operation with single ended inputs. As shown in Figure 30, the input common mode voltage is less than the output common voltage. It is set by current flowing through the feedback network from the device output. The input common mode range of 0.4V to 3.2V places constraints on gain settings. Possible solutions to this limitation include AC coupling the input signal, using split power supplies and limiting stage gain. AC coupling with single supply is shown in Figure 31. In Figure 30 closed loop gain = VO / VI ≊ RF / RG, where VI =VS / 2, as long as RM