OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 GAIN +4 STABLE WIDEBAND VOLTAGE LIMITING AMPLIFIER FEATURES APPLICATIONS • • • • • • • • • • • • • • High Linearity Near Limiting Fast Recovery from Overdrive: 1 ns Limiting Voltage Accuracy: ±15 mV –3-dB Bandwidth (G = +6): 260 MHz Stable for G ≥ +4 Slew Rate: 1400 V/µs ±5-V and 5-V Supply Operation High Gain Version of the OPA698 Low Prop Delay Comparator Non-Linear Analog Signal Processing Difference Amplifier IF Limiting Amplifier OPA689M Replacement • Transimpedance With Fast Overdrive Recovery Fast Limiting ADC Input Buffers JD PACKAGE (TOP VIEW) NC INVERTING INPUT NONINVERTING INPUT -V S 1 8 2 7 3 6 4 5 VH +VS OUTPUT VL NC - No internal connection P0013-01 DESCRIPTION The OPA699 is a wideband, voltage feedback op amp that offers bipolar output voltage limiting, and is stable for gains ≥ +4. 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 ±15 mV. The op amp operates linearly to within 30 mV of the limits. The combination of narrow nonlinear range and low limiting offset allows the limiting voltages to be set within 100 mV of the desired linear output range 1-ns 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 OPA699 to be used in all standard op amp applications. Non-linear analog signal processing circuits will benefit from the ability of the OPA699 to sharply transition from linear operation to output limiting. The quick recovery time supports high speed applications. The OPA699M is available in an industry-standard pinout in a CDIP-8 package. For lower gain applications requiring output limiting with fast recovery, consider the OPA698M. ORDERING INFORMATION (1) TA -55°C to 125°C (1) PACKAGE CDIP – JD Tube ORDERABLE PART NUMBER TOP-SIDE MARKING OPA699MJD OPA699MJD Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are available at www.ti.com/sc/package. 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. 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 © 2005–2006, Texas Instruments Incorporated OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 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 over operating free-air temperature range (unless otherwise noted) (1) UNIT Power supply ±6.5 V VICM Common-mode input voltage ±VS VID Differential input voltage ±VS Limiter voltage range ±(VS - 0.7 V) TA Operating free-air temperature range –55°C to 125°C Tstg Storage temperature range –65°C to 150°C Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds 300°C Case temperature for 10 seconds 260°C TJ Junction temperature θJC Package thermal impedance (2) (JD Package) (1) (2) 150°C 14.5°C/W Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. The package thermal impedance is measured per MIL-STD-883, Method 1012.1. RECOMMENDED OPERATING CONDITIONS MIN Operating voltage Split-rail operation Single-supply operation Operating free-air temperature 2 –55 Submit Documentation Feedback NOM MAX ±5 ±6 5 12 125 UNIT V °C OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 ELECTRICAL CHARACTERISTICS VS = ±5 V, VICM = 0 V, RL = 500 Ω, limiter pins open (unless otherwise noted) (1) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT AC PERFORMANCE (see Figure 47) VO < 0.5 Vp-p, G = +6 Small signal bandwidth 260 VO < 0.5 Vp-p, G = +12 86 VO < 0.5 Vp-p, G = –6 269 MHz Gain bandwidth product (G ≥ +20) VO < 0.5 Vp-p Gain peaking VO = 0.5 V, G = +4 7.5 dB Bandwidth for 0.1-dB gain flatness VO = 0.5 V 30 MHz Large signal bandwidth VO = 2 Vp-p 290 MHz Slew rate VO = 2 V step 1400 V/µs Rise and falll time VO = 0.5 V step Settling time to 0.05% VO = 2 V step 1000 MHz 1.6 ns 8 ns Even 67 Odd 87 Spurious free dynamic range VO = 2 Vp-p, f = 5 MHz dB Differential gain RL = 500 Ω, NTSC, PAL 0.012% Differential phase RL = 500 Ω, NTSC, PAL 0.008 Input noise, voltage noise density f ≥ 1 MHz 4.1 nV/√Hz Input noise, current noise density f ≥ 1 MHz 2 pA/√Hz ° DC PERFORMANCE Open-loop voltage gain (AVOL) VO = ±0.5 V TA = 25°C 54 TA = Full range 47 TA = 25°C Input offset voltage (VIO) 62 ±1.5 TA = Full range 3 TA = Full range ±10 ±18 TA = 25°C Input offset current (IIO) ±8 ±12 TA = 25°C Input bias current (IIB) (2) dB ±0.3 TA = Full range ±3 ±4 mV µA µA INPUT Common-mode rejection ratio (CMRR) VICM = ±0.5 V, Input referred Common-mode input voltage range (VICR) (3) TA = 25°C 54 TA = Full range 50 TA = 25°C ±3.2 TA = Full range ±3.1 Input impedance, differential mode Input impedance, common mode 62 ±3.3 dB V 0.32 1 MΩ pF 3.5 1 MΩ pF OUTPUT Output voltage range (VOH, VOL) VH = 4.3 V, VL = -4.3 V, RL≥ 500 Ω TA = 25°C ±3.9 TA = Full range ±3.7 Current output, sourcing (IOH) VH = 4.3 V, VL = -4.3 V, RL = 20 Ω TA = 25°C 110 TA = Full range 100 Current output, sinking (IOL) VH = 4.3 V, VL = -4.3 V, RL = 20 Ω TA = 25°C –90 TA = Full range –80 Closed-loop output impedance G = +4, f < 100 kHz (1) (2) (3) ±4.1 165 –130 0.8 V mA mA Ω All typical limits are at TA = 25°C unless otherwise specified. Current is considered positive out of node. CMIR tested as <3-dB degradation from minimum CMRR at specified limits. Submit Documentation Feedback 3 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 ELECTRICAL CHARACTERISTICS (continued) VS = ±5 V, VICM = 0 V, RL = 500 Ω, limiter pins open (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX ±5 ±6 15 15.5 16 UNIT POWER SUPPLY Operating voltage (VS) TA = 25°C Quiescent current (IS) ower supply rejection ratio (PSRR) TA = Full range Input referred, VS = ±4.5 V to ±5.5 V 13.5 TA = 25°C 65 TA = Full range 60 18 76 V mA dB OUTPUT VOLTAGE LIMITERS (PINS 5 AND 8) Default output limited voltage Limiter pins open Limiter output offset voltage (VO– VH) or (VO– VL) Limiter input bias current magnitude (4) VO = 0 V TA = 25°C TA = Full range ±3.3 TA = Full range TA = 25°C 40 TA = Full range 35 ±15 ±50 55 65 70 f = 5 MHz 400 Op amp bias current shift(2) Limter slew rate (6) V mV 3 VI = ±2 V, VO < 0.02 Vp-p µA dB ±4.3 Minimum limiter voltage separation mV MΩ pF –60 Maximum limiter voltage Limiter small signal bandwidth V 3.4 1 Limiter input impedance Limiter feedthrough (5) ±3.6 ±3 µA 600 MHz 125 V/µs mV Limiter step response, overshoot VI = ±2 V 250 Limiter step response, recovery time VI = ±2 V 1 ns Linearity guardband (7) VO = 2 Vp-p, f = 5 MHz 30 mV (4) (5) (6) (7) 4 IVH (VH bias current) is positive and IVL (VL bias current) is negative, under these conditions. See Note 2, Figure 47, and Figure 58. Limiter feedthrough is the ratio of the output magnitude to the sinewave added to VH (or VL) when VIN = 0. VH slew rate conditions are: VIN = +0.7 V, G = +6, VL = -2 V, VH = step between 2 V and 0 V. VL slew rate conditions are similar. Linearity Guardband is defined for an output sinusoid (f = 1 MHz, VO = 2 Vp-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 3 dB (see Figure 59). Submit Documentation Feedback OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 ELECTRICAL CHARACTERISTICS VS = 5 V, VICM = 2.5 V, RL = 500 Ω, limiter pins open (unless otherwise noted) (1) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT AC PERFORMANCE (see Figure 48) VO < 0.5 Vp-p, G = +6 Small signal bandwidth 234 VO < 0.5 Vp-p, G = +12 83 VO < 0.5 Vp-p, G = –6 242 Gain bandwidth product VO < 0.5 Vp-p, G ≥ +20 880 Gain peaking VO < 0.5 V, G = +4 Bandwidth for 0.1-dB gain flatness VO = 0.5 Vp-p Large signal bandwidth VO = 2 Vp-p Slew rate Rise and falll time Settling time to 0.05% 2 V step MHz MHz 8 dB 30 MHz 250 MHz VO = 2 V step 1050 V/µs VO = 0.5 V step 1.75 ns 8 ns Even 64 Odd 70 Spurious free dynamic range VO = 2 Vp-p, f = 5 MHz dB Input noise, voltage noise density f ≥ 1 MHz 4.2 nV/√Hz Input noise, current noise density f ≥ 1 MHz 2.1 pA/√Hz DC PERFORMANCE Open-loop voltage gain (AVOL) VO = ±0.4 V TA = 25°C 54 TA = Full range 47 TA = 25°C Input offset voltage (VIO) 61 ±2 TA = Full range ±3 TA = Full range ±10 ±15 TA = 25°C Input offset current (IIO) ±8 ±12 TA = 25°C Input bias current (IIB) (2) dB ±0.4 TA = Full range ±3 ±4 mV µA µA INPUT VICM = ±0.5 V, Input referred Common-mode rejection ratio (CMRR) TA = 25°C 52 TA = Full range 48 TA = 25°C VICM ±0.7V TA = Full range VICM ±0.6V ) (3) Common-mode input voltage range (VICR Input impedance, differential mode Input impedance, common mode 60 VICM ±0.8V dB V 0.32 1 MΩ pF 1 1 MΩ pF OUTPUT Output voltage range (VOH, VOL) VH = VICM + 1.8 V, VL = VICM – 1.8 V, RL ≥ 500 Ω Current output, sourcing (IOH) VS = ±2.5 V, RL = 20 Ω Current output, sinking (IOL) VS = ±2.5 V, RL = 20 Ω Closed-loop output impedance G = +4, f < 100 kHz (1) (2) (3) TA = 25°C VICM ±1.4V TA = Full range VICM ±1.3V TA = 25°C 70 TA = Full range 60 TA = 25°C –60 TA = Full range –50 VICM ±1.6V 100 –90 0.2 V mA mA Ω All typical limits are at TA = 25°C unless otherwise specified. Current is considered positive out of node. CMIR tested as <3-dB degradation from minimum CMRR at specified limits. Submit Documentation Feedback 5 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 ELECTRICAL CHARACTERISTICS (continued) VS = 5 V, VICM = 2.5 V, RL = 500 Ω, limiter pins open (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX 5 12 13.5 14.3 15 UNIT POWER SUPPLY Operating voltage (VS) TA = 25°C Quiescent current (IS) Power supply rejection ratio (PSRR) TA = Full range Input referred, VS = 4 V to 6 V 12 16.5 58 74 TA = 25°C VICM ±0.8V VICM ±1.1V TA = Full range VICM ±0.6V TA = Full range V mA dB OUTPUT VOLTAGE LIMITERS (PINS 5 AND 8) Default output limited voltage Limiter output offset voltage Limiter input bias current magnitude (4) Limiter pins open (VO – VH) or (VO – VL) VO = 2.5 V TA = Full range TA = 25°C 40 TA = Full range 35 V ±15 ±50 50 65 70 mV µA Limiter input bias current drift 30 nA/°C Limiter input impedance 3.4 1 MΩ pF Limiter feedthrough (5) f = 5 MHz –60 Maximum limiter voltage Minimum limiter voltage separation 400 Output bias current shift(2) Limiter small signal bandwidth dB VICM ±1.8V mV 5 VI = VICM ±0.4 V, VO < 0.02 Vp-p Limter slew rate (6) V µA 450 MHz 100 V/µs mV Limiter step response, overshoot VI = VICM ±0.4 V 55 Limiter step response, recovery time VI = VICM ±0.4 V 3 ns Linearity guardband (7) VO = 2 Vp-p, f = 5 MHz 30 mV (4) (5) (6) (7) 6 IVH (VH bias current) is positive and IVL (VL bias current) is negative, under these conditions. See Note 2, Figure 47, and Figure 58. Limiter feedthrough is the ratio of the output magnitude to the sinewave added to VH (or VL) when VIN = 0. VH slew rate conditions are: VIN = 0.7 V, G = +6, VL = -2 V, VH = stepped between 2 V and 0 V. VL slew rate conditions are similar. Linearity Guardband is defined for an output sinusoid (f = 1 MHz, VO = 2 Vp-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 3 dB (see Figure 59). Submit Documentation Feedback OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 TYPICAL CHARACTERISTICS: VS = ±5 V TA = 25°C, G = +6, RF = 750 Ω, and RL = 500 Ω, VH = –VL = 2 V, unless otherwise noted NONINVERTING SMALL-SIGNAL FREQUENCY RESPONSE INVERTING SMALL-SIGNAL FREQUENCY RESPONSE 6 9 6 G = +6 3 0 -3 G = +12 -6 -9 G = -4 VO = 0.5VPP 3 Normalized Gain (dB) Normalized Gain (dB) G = +4 VO = 0.5VPP G = -6 0 -3 G = -12 -6 -9 -12 G = +20 -15 -12 See Figure 47 -18 -15 1M 10M 100M 1M 1G Frequency (Hz) 1G G001 G002 Figure 2. NONINVERTING LARGE-SIGNAL FREQUENCY RESPONSE INVERTING LARGE-SIGNAL FREQUENCY RESPONSE 18 VO = 1VPP 15 15 VO = 2VPP Gain (dB) VO = 4VPP 12 VO = 7VPP 9 VO = 1VPP G = -6 6 VO = 2VPP VO = 4VPP 12 VO = 7VPP 9 6 See Figure 47 See Figure 49 3 3 1M 10M 100M 1M 1G Frequency (Hz) 10M 100M 1G Frequency (Hz) G003 Figure 3. Figure 4. VH–LIMITER SMALL-SIGNAL FREQUENCY RESPONSE VL–LIMITER SMALL-SIGNAL FREQUENCY RESPONSE G004 3 3 VO = 0.02VPP VO = 0.02VPP 0 Limiter Gain (dB) 0 Limiter Gain (dB) 100M Figure 1. G = +6 0.02VPP + 2.0VDC -3 10M Frequency (Hz) 18 Gain (dB) See Figure 49 0.7VDC 125Ω VH VO OPA699 VL -3 VH VO OPA699 VL 0.02VPP + 2.0VDC -6 Open -6 Open 0.7VDC 125Ω 150Ω 750Ω 150Ω 750Ω -9 -9 1M 10M 100M Frequency (Hz) 1M 1G G005 Figure 5. 10M 100M Frequency (Hz) 1G G006 Figure 6. Submit Documentation Feedback 7 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 TYPICAL CHARACTERISTICS: VS = ±5 V (continued) TA = 25°C, G = +6, RF = 750 Ω, and RL = 500 Ω, VH = –VL = 2 V, unless otherwise noted SMALL-SIGNAL PULSE RESPONSE LARGE-SIGNAL PULSE RESPONSE 0.4 2.5 VO = 0.5VPP VO = 4VPP VH = -VL = 2.5V 2.0 0.3 1.5 0.2 1.0 VOUT (V) VOUT (V) 0.1 0 -0.1 0.5 0 -0.5 -1.0 -0.2 -1.5 -0.3 -2.0 See Figure 47 -0.4 See Figure 47 -2.5 Time (5ns/div) Time (5ns/div) G007 G008 Figure 7. Figure 8. VH–LIMITED PULSE RESPONSE VL–LIMITED PULSE RESPONSE 2.5 2.5 VOUT 1.5 1.0 VIN 0.5 0 -0.5 -1.0 -1.5 -2.0 G=+6 VL = −2V VIN = 0→−0.7V 2.0 Input and Output Voltage (V) Input and Output Voltage (V) 2.0 G = +6 VH = +2V VIN = 0 → 0.7V 1.5 1.0 0.5 0 VIN −0.5 −1.0 −1.5 VOUT −2.0 −2.5 -2.5 Time (5ns/div) Time (5ns/div) G010 G009 Figure 9. Figure 10. LIMITED OUTPUT RESPONSES DETAIL OF LIMITED OUTPUT RESPONSE 2.10 2.5 G = +6 VH = 2V VL = -2V 1.5 2.05 2.00 Output Voltage (V) Input and Output Voltage (V) 2.0 1.0 0.5 0 VIN -0.5 -1.0 -1.5 -2.0 VOUT 1.95 1.90 1.85 1.80 1.75 1.70 VOUT 1.65 1.60 -2.5 Time (50ns/div) Time (200ns/div) G012 G011 Figure 11. 8 Figure 12. Submit Documentation Feedback OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 TYPICAL CHARACTERISTICS: VS = ±5 V (continued) TA = 25°C, G = +6, RF = 750 Ω, and RL = 500 Ω, VH = –VL = 2 V, unless otherwise noted HARMONIC DISTORTION vs LOAD RESISTANCE 5 MHz HARMONIC DISTORTION vs SUPPLY VOLTAGE -60 -55 2nd-Harmonic Harmonic Distortion (dBc) Harmonic Distortion (dBc) -60 -65 -70 -75 3rd-Harmonic -80 -85 -70 -75 -80 3rd-Harmonic -85 -90 1k 100 Load Resistance (Ω) 2.5 G013 5.0 HARMONIC DISTORTION vs OUTPUT VOLTAGE -55 2nd-Harmonic Harmonic Distortion (dBc) -70 -75 -80 -85 -90 3rd-Harmonic -105 1 10 Frequency (MHz) 5.5 6.0 G014 RL = 500Ω VH = -VL = VOPP /2 + 0.5V f = 5MHz -60 2nd-Harmonic -65 -70 3rd-Harmonic -75 -80 -85 See Figure 47 See Figure 47 0.5 4.5 HARMONIC DISTORTION vs FREQUENCY -65 -100 4.0 Figure 14. -50 -95 3.5 Figure 13. VO = 2VPP RL = 500Ω -60 3.0 ± Supply Voltage (V) -55 Harmonic Distortion (dBc) -65 See Figure 47 See Figure 47 -90 VO = 2VPP RL = 500Ω 2nd-Harmonic VO = 2VPP f = 5MHz -90 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 20 G015 Figure 15. Output Voltage (VPP) G016 Figure 16. Submit Documentation Feedback 9 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 TYPICAL CHARACTERISTICS: VS = ±5 V (continued) TA = 25°C, G = +6, RF = 750 Ω, and RL = 500 Ω, VH = –VL = 2 V, unless otherwise noted HARMONIC DISTORTION vs NONINVERTING GAIN -60 Harmonic Distortion (dBc) -55 VO = 2VPP RL = 500Ω f = 5MHz 2nd-Harmonic -65 -70 -75 3rd-Harmonic -80 -85 2nd-Harmonic -65 -70 -75 3rd-Harmonic -80 -85 -90 -95 -90 4 8 12 20 16 Gain (V/V) -4 -8 -12 -20 -16 Gain (V/V) G017 G018 Figure 17. Figure 18. HARMONIC DISTORTION NEAR LIMITING VOLTAGES 2-TONE, 3rd-ORDER INTERMODULATION INTERCEPT -40 38 VO = 0VDC ± 1VP f = 5MHz RL = 500Ω -50 G = +6V/V 36 Intercept Point (+dBm) Harmonic Distortion (dBc) VO = 2VPP RL = 500Ω f = 5MHz -60 Harmonic Distortion (dBc) -55 HARMONIC DISTORTION vs INVERTING GAIN -60 2nd-Harmonic -70 3rd-Harmonic -80 34 32 Open PI 30 VH PO OPA699 28 500Ω VL Open 26 24 150Ω 750Ω 22 -90 20 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 ± Limit Voltage (V) 1.7 1.8 1.9 0 2.0 G019 Figure 19. 10 10 20 30 Frequency (MHz) Figure 20. Submit Documentation Feedback 40 50 G020 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 TYPICAL CHARACTERISTICS: VS = ±5 V (continued) TA = 25°C, G = +6, RF = 750 Ω, and RL = 500 Ω, VH = –VL = 2 V, unless otherwise noted RECOMMENDED R8 vs CAPACITIVE LOAD FREQUENCY RESPONSE vs CAPACITIVE LOAD 140 18 Gain to Capacitive Load (dB) Resistance (Ω) 120 100 80 60 40 20 CL = Open 15 CL = 10pF CL = 1000pF 12 VO = 0.5VPP G = +6 9 CL = 100pF VIN RS 6 OPA699 CL 1kΩ(1) 750Ω 3 150Ω Note: (1) 1kΩ(1) is optional. 0 0 10 100 1000 Capacitive Load (pF) 1M 100M 1G Frequency (Hz) G021 G022 Figure 21. Figure 22. INPUT VOLTAGE AND CURRENT NOISE DENSITY OPEN-LOOP GAIN AND PHASE 100 70 0 Gain 60 Open-Loop Gain (dB) Voltage Noise Density (nV/√Hz) Current Noise Density (pA/√Hz) 10M 10 Voltage Noise (4.1nV/√Hz) Current Noise (2pA/√Hz) -30 VO = 0.5VPP 50 -60 40 -90 30 -120 Phase 20 -150 10 -180 0 -210 -10 1 100 1k 10k 100k Frequency (Hz) 1M 10M Open-Loop Phase (°) 1 -240 10k 100k 1M 10M Frequency (Hz) G023 Figure 23. 100M 1G G024 Figure 24. Submit Documentation Feedback 11 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 TYPICAL CHARACTERISTICS: VS = ±5 V (continued) TA = 25°C, G = +6, RF = 750 Ω, and RL = 500 Ω, VH = –VL = 2 V, unless otherwise noted VOLTAGE RANGES vs TEMPERATURE LIMITED VOLTAGE RANGE vs TEMPERATURE 4.0 5.0 VH and VL left open Internal Default Limited Voltage 3.9 3.8 4.5 VH 3.7 Voltage (V) ±Voltage Ranges (V) VH = -VL = 4.3V Output Voltage Range 4.0 3.6 VL 3.5 3.4 3.3 3.5 3.2 Common-Mode Input Range 3.1 3.0 3.0 -50 -25 0 25 50 100 75 Ambient Temperature (°C) -50 25 50 75 100 G026 Figure 25. Figure 26. LIMITED INPUT BIAS CURRENT vs BIAS VOLTAGE SUPPLY AND OUTPUT CURRENTS vs TEMPERATURE 20 100 Output Current, Sinking 75 18 Supply Current (mA) Minimum Over Temperature 25 0 -25 -50 Limiter Headroom = +VS - VH = VL - (-VS) Current = IVH or -IVL -75 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Limiter Headroom (V) 4.0 4.5 98 Output Current, Sourcing 16 96 Supply Current 14 94 12 92 10 -50 5.0 Output Currents (mA) Maximum Over Temperature 50 -100 -25 0 25 50 Ambient Temperature (°C) G027 Figure 27. 12 0 Ambient Temperature (°C) 100 Limiter Input Bias Current (µA) -25 G025 Figure 28. Submit Documentation Feedback 75 90 100 G028 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 TYPICAL CHARACTERISTICS: VS = ±5 V (continued) TA = 25°C, G = +6, RF = 750 Ω, and RL = 500 Ω, VH = –VL = 2 V, unless otherwise noted TYPICAL DRIFT OVER TEMPERATURE 80 -PSRR CMRR 60 Input Bias Current (∝A) CMRR and PSRR (dB) 70 +PSRR 50 40 30 20 4.5 1 4.0 0.9 3.5 0.8 3.0 2.5 0.5 1.5 0.5 0 Frequency (Hz) 0 −25 0 25 50 75 100 Ambient Temperature (C) G030 G029 Figure 29. Figure 30. LIMITER FEEDTHROUGH CLOSSED-LOOP OUTPUT IMPEDANCE -45 100 G = +4 VO = 0.5VPP -50 -60 Output Impedance (Ω) -55 Feedthrough (dB) 0.2 0.1 100M 10M 0.3 Input Offset Current (I OS) −0.5 −50 1M 0.4 Input Offset Voltage (V OS) 1.0 0 100k 0.6 2.0 10 10k 0.7 Input Bias Current (I B) InputOffset OffsetVoltage Voltage(mV) (mA) Input Input InputOffset OffsetCurrent Current(µA) (∝A) CMRR AND POWER-SUPPLY REJECTION vs FREQUENCY 0.02VPP + 2VDC -65 125Ω VH VO -70 OPA699 -75 VL -80 Open -85 150Ω 10 1 0.1 750Ω -90 0.01 -95 1 10 Frequency (MHz) 100 1M G031 Figure 31. 10M 100M Frequency (Hz) 1G G032 Figure 32. Submit Documentation Feedback 13 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 TYPICAL CHARACTERISTICS: VS = ±5 V (continued) TA = 25°C, G = +6, RF = 750 Ω, and RL = 500 Ω, VH = –VL = 2 V, unless otherwise noted CMRR AND PSRR(±) vs TEMPERATURE OUTPUT VOLTAGE AND CURRENT LIMITATIONS 100 5 90 VH = -VL = 4.3V 1W Internal Power Limit 3 Output Voltage (V) CMRR and PSRR (dB) 4 +PSRR 80 70 -PSRR 60 2 1 0 RL = 25Ω -1 RL = 50Ω -2 RL = 100Ω -3 CMRR -50 -25 0 1W Internal Power Limit -4 50 25 50 75 -5 -400 100 Ambient Temperature (°C) -300 -200 -100 0 100 200 300 400 Output Current (mA) G033 Figure 33. G034 Figure 34. TYPICAL CHARACTERISTICS VS = +5 V TA = 25°C, G = +6, RF = 750 Ω, and RL = 500 Ω to VCM = +2.5 V, VL = VCM– 1.2 V, VH = VCM + 1.2 V, unless otherwise noted NONINVERTING SMALL-SIGNAL FREQUENCY RESPONSE 9 INVERTING SMALL-SIGNAL FREQUENCY RESPONSE 6 VO = 0.5VPP 3 3 Normalized Gain (dB) Normalized Gain (dB) 6 G = +6 0 -3 -6 G = +20 -9 G = +12 0 G = -6 -3 G = -12 -6 -9 -12 -12 See Figure 49 See Figure 48 -15 -15 1M 10M 100M Frequency (Hz) 1G 1M G035 Figure 35. 14 G = -4 VO = 0.5VPP G = +4 10M 100M Frequency (Hz) Figure 36. Submit Documentation Feedback 1G G036 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 TYPICAL CHARACTERISTICS VS = +5 V (continued) TA = 25°C, G = +6, RF = 750 Ω, and RL = 500 Ω to VCM = +2.5 V, VL = VCM– 1.2 V, VH = VCM + 1.2 V, unless otherwise noted LARGE-SIGNAL FREQUENCY RESPONSE 18 0.4 VO = 1VPP, VLIM = VCM ±1.2V 15 G = +6 0.3 VO = 3VPP, VLIM = VCM ±1.2V 12 0.2 0.1 VO = 2VPP, VLIM = VCM ±1.5V 9 VOUT (V) Gain (dB) SMALL-SIGNAL PULSE RESPONSE 6 VLIM = VH = −VL 0 -0.1 -0.2 3 -0.3 See Figure 48 See Figure 48 0 -0.4 0.1 10M 100M 1G Frequency (Hz) Time (5ns/div) G037 G038 Figure 37. Figure 38. LARGE-SIGNAL PULSE RESPONSE VH AND VL– LIMITED PULSE RESPONSE 2.5 1.5 G = +6 2.0 Input and Output Voltage (V) 1.0 VOUT (V) 0.5 0 -0.5 -1.0 VOUT 1.5 1.0 0.5 VIN 0 -0.5 -1.0 -1.5 -2.0 See Figure 48 -1.5 -2.5 Time (20ns/div) Time (5ns/div) G040 G039 Figure 40. HARMONIC DISTORTION vs LOAD RESISTANCE HARMONIC DISTORTION vs FREQUENCY -50 VO = 2VPP f = 5MHz VO = 2VPP RL = 500Ω -55 -55 Harmonic Distortion (dBc) Harmonic Distortion (dBc) -50 Figure 39. 2nd-Harmonic -60 -65 3rd-Harmonic -70 -75 -60 2nd-Harmonic -65 -70 -75 3rd-Harmonic -80 -85 See Figure 48 See Figure 48 -80 -90 1k 100 Load Resistance (Ω) 0.5 G041 Figure 41. 1 10 Frequency (MHz) 20 G042 Figure 42. Submit Documentation Feedback 15 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 TYPICAL CHARACTERISTICS VS = +5 V (continued) TA = 25°C, G = +6, RF = 750 Ω, and RL = 500 Ω to VCM = +2.5 V, VL = VCM– 1.2 V, VH = VCM + 1.2 V, unless otherwise noted 2-TONE, 3rd-ORDER INTERMODULATION INTERCEPT HARMONIC DISTORTION vs OUTPUT VOLTAGE -60 38 36 -65 Intercept Point (+dBM) Harmonic Distortion (dBc) 2nd-Harmonic -70 3rd-Harmonic -75 RL = 500Ω to VS/2 f = 5MHz VH = VCM + VOPP/2 + 0.5V VL = VCM + VOPP/2 + 0.5V -80 See Figure 48 32 Open 30 PI VH PO 28 OPA699 26 VL Open 500Ω 24 750Ω 150Ω 22 20 -85 0.5 1.0 1.5 0 2.5 2.0 Output Voltage Swing (VPP) 20 30 G043 LIMITER INPUT BIAS CURRENT vs BIAS VOLTAGE 100 Limiter Input Bias Current (µA) -50 -55 -60 2nd-Harmonic -65 -70 3rd-Harmonic -75 75 Maximum Over Temperature 50 25 Minimum Over Temperature 0 -25 -50 Limiter Headroom = +VS - VH = VL - (-VS) Current = IVH or -IVL -75 -100 -80 1.0 1.1 1.2 1.3 1.4 1.5 Limit Voltages - 2.5V 1.6 1.7 50 G044 HARMONIC DISTORTION NEAR LIMITING VOLTAGES VO = VCM ±1VP f = 5MHz RL = 500Ω 0.9 40 Frequency (MHz) Figure 44. -45 1.8 0 G045 Figure 45. 16 10 Figure 43. -40 Harmonic Distortion (dBc) 34 0.5 1.0 1.5 Limiter Headroom (V) Figure 46. Submit Documentation Feedback 2.0 2.5 G046 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 APPLICATION INFORMATION DUAL-SUPPLY, NON-INVERTING AMPLIFIER The OPA699 is a +4 V/V minimum gain voltage-feedback amplifier that combines features of a wideband, high slew rate amplifier with output voltage limiters. Its output can swing up to 1 V from each rail and can deliver up to 120 mA. These capabilities make it an ideal interface to drive an ADC while adding overdrive protection for the ADC inputs. Figure 47 shows the ac-coupled, gain of +6 V/V, dual power-supply circuit configuration used as the basis of the ±5-V Electrical Characteristics and Typical Characteristics. For test purposes, the input impedance is set to 50 Ω with a resistor to ground and the output is set to 500 Ω. Voltage swings reported in the specifications are taken directly at the input and output pins. For the circuit of Figure 47, the total output load will be 500 Ω || 900 Ω = 321 Ω. The voltage limiting pins are set to ±2 V through a voltage divider network between +VS and ground for VH and between –VS and ground for VL. These limiter voltages are adequately bypassed with a 0.1-µF ceramic capacitor to ground. The limiter voltages (VH and VL) and the respective bias currents (IVH and IVL) have the polarities shown. One additional component is included in Figure 47. An additional resistor (100 Ω) is included in series with the noninverting input. Combined with the 25-Ω dc source resistance looking back towards the signal generator, this gives an input bias current-canceling resistance that matches the 125-Ω source resistance seen at the inverting input (see the dc accuracy and offset control section). The power-supply bypass for each supply consists of two capacitors: one electrolytic 2.2 µF and one ceramic 0.1 µF. The power-supply bypass capacitors are shown explicitly in Figure 47 and Figure 48, but will be assumed in the other figures. An additional 0.01-µF power-supply decoupling capacitor (not shown here) can be included between the two power-supply pins. In practical PC board layouts, this optional, added capacitor typically improves the 2nd harmonic distortion performance by 3 dB to 6 dB. 3.01kΩ 1.91kΩ +VS = +5V + 2.2µF 0.1µF 0.1µF VH = +2V 100Ω 7 3 VIN 8 49.9Ω OPA699 2 RG 150Ω RF 750Ω 0.1µF 5 IVH 6 IVL VO 500Ω 4 0.1µF VL = -2V + 2.2µF 3.01kΩ 1.91kΩ -VS = -5V S0035-02 Figure 47. DC-Coupled, Dual Supply Amplifier SINGLE-SUPPLY, NON-INVERTING AMPLIFIER Figure 48 shows an ac-coupled, noninverting gain amplifier for single +5-V supply operation. This circuit was used for ac characterization of the OPA699, with a 50-Ω source (which it matches) and a 500-Ω load. The mid-point reference on the noninverting input is set by two 1.5-kΩ resistors. This gives an input bias current-canceling resistance that matches the 750-Ω dc source resistance seen at the inverting input (see the dc accuracy and offset control section). The power-supply bypass for the supply consists of two capacitors: one electrolytic 2.2 µF and one ceramic 0.1 µF. The power-supply bypass capacitors are shown explicitly in Figure 47 Submit Documentation Feedback 17 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 APPLICATION INFORMATION (continued) and Figure 48, but will be assumed in the other figures. The limiter voltages (VH and VL) and the respective bias currents (IVH and IVL) have the polarities shown. These limiter voltages are adequately bypassed with a 0.1-µF ceramic capacitor to ground. Notice that the single-supply circuit can use three resistors to set VH and VL, where the dual-supply circuit usually uses four to reference the limit voltages to ground. While this circuit shows +5-V operation, the same circuit may be used for single supplies up to +12 V. VS = +5V + 0.1µF 2.2µF 523Ω 0.1µF VH = 3.7V 1.5kΩ 0.1µF 3 IVH 7 VIN 8 53.6Ω 1.5kΩ 0.1µF 6 OPA699 2 976Ω VO 5 500Ω IVL 4 RF 750Ω 0.1µF RG 150Ω VL = 1.3V 523Ω 0.1µF S0036-02 Figure 48. AC-Coupled, Single Supply Amplifier WIDEBAND INVERTING OPERATION Operating the OPA699 as an inverting amplifier has several benefits and is particularly useful when a matched 50-Ω source and input impedance are required. Figure 49 shows the inverting gain of –4 V/V circuit used as the basis of the inverting mode typical characteristics. +5V 0.1µF RT 169Ω +2V VH OPA699 VO VL 500Ω -5V 50Ω Source RG 187Ω -2V RF 750Ω VI RM 68.1Ω S0037-02 Figure 49. Inverting G = –4 Specifications and Test Circuit In the inverting case, only the feedback resistor appears as part of the total output load in parallel with the actual load. For a 500-Ω load used in the typical characteristics, this gives a total load of 329 Ω in this inverting 18 Submit Documentation Feedback OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 APPLICATION INFORMATION (continued) configuration. The gain resistor is set to get the desired gain (in this case, 187 Ω for a gain of –4) while an additional input resistor (RM) can be used to set the total input impedance equal to the source, if desired. In this case, RM = 68.1 Ω in parallel with the 187-Ω gain setting resistor gives a matched input impedance of 50 Ω. This matching is only needed when the input needs to be matched to a source impedance, as in the characterization testing done using the circuit of Figure 49. For bias current-cancellation matching, the noninverting input requires a 169-Ω resistor to ground. The calculation for this resistor includes a dc-coupled 50-Ω source impedance along with RG and RM. Although this resistor provides cancellation for the bias current, it must be well-decoupled (0.1 µF in Figure 49) to filter the noise contribution of the resistor and the input current noise. As the required RG resistor approaches 50 Ω at higher gains, the bandwidth for the circuit in Figure 49 far exceeds the bandwidth at that same gain magnitude for the noninverting circuit of Figure 47. This occurs due to the lower noise gain for the circuit of Figure 49 when the 50-Ω source impedance is included in the analysis. For instance, at a signal gain of –15 (RG = 50 Ω, RM = open, RF = 750 Ω) the noise gain for the circuit of Figure 49 will be 1 + 750 Ω/(50 Ω + 50 Ω) = 8.5 due to the addition of the 50-Ω source in the noise gain equation. This approach gives considerably higher bandwidth than the noninverting gain of +15. Using the 1-GHz gain bandwidth product for the OPA699, an inverting gain of –15 from a 50-Ω source to a 50-Ω RG gives 140-MHz bandwidth, whereas the noninverting gain of +6 gives 55 MHz, as shown in the measured results of Figure 50. 24 G = -15 Gain (dB) 21 18 G = +15 15 12 9 1M 10M 100M Frequency (Hz) 1G G047 Figure 50. G = +15 and -15 Frequency Response LOW-GAIN COMPENSATION FOR IMPROVED SFDR Where a low gain is desired and inverting operation is acceptable, a new external compensation technique can be used to retain the full slew rate and noise benefits of the OPA699, while giving increased loop gain and the associated distortion improvements offered by a non-unity-gain stable op amp. This technique shapes the loop gain for good stability, while giving an easily controlled 2nd-order low-pass frequency response. To set the compensation capacitors (CS and CF), consider the half-circuit of Figure 51, where the 50-Ω source is used. Considering only the noise gain for the circuit of Figure 51, the low-frequency noise gain (NG1) is set by the resistor ratio, while the high-frequency noise gain (NG2) is set by the capacitor ratio. The capacitor values set both the transition frequencies and the high-frequency noise gain. If the high-frequency noise gain, determined by NG2 = 1 + CS/CF, is set to a value greater than the recommended minimum stable gain for the op amp, and the noise gain pole (set by 1/RFCF) is placed correctly, a well controlled 2nd-order low-pass frequency response results. Submit Documentation Feedback 19 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 APPLICATION INFORMATION (continued) +5V VH 200Ω OPA699 VO VL RG 402Ω RF 402Ω VI CS 13pF CF 2.8pF -5V S0052-01 Figure 51. Broadband, Low-Inverting Gain External Compensation To choose the values for both CS and CF, two parameters and only three equations need to be solved. The first parameter is the target high-frequency noise gain (NG2), which should be greater than the minimum stable gain for the OPA699. Here, a target of NG2 = 26 is used. The second parameter is the desired low-frequency signal gain, which also sets the low-frequency noise gain (NG1). To simplify this discussion, we target a maximally flat 2nd-order low-pass Butterworth frequency response (Q = 0.707). The signal gain shown in Figure 51 sets the low-frequency noise gain to NG1 = 1 + RF/RG (= 2 in this example). Then, using only these two gains and the gain bandwidth product for the OPA699 (1000 MHz), the key frequency in the compensation is set by Equation 1. Z GBP2 O NG 1 N 1 G1 N G2 N G2 N 12 G1 (1) Physically, this ZO (22.3 MHz for the values shown above) is set by 1/[2πRF(CF + CS)] and is the frequency at which the rising portion of the noise gain would intersect the unity gain if projected back to a 0 dB gain. The actual zero in the noise gain occurs at NG1 × ZO and the pole in the noise gain occurs at NG2 × ZO. That pole is physically set by 1/(RFCF). Since GBP is expressed in Hz, multiply ZO by 2π and use to get CF by solving Equation 2. 1 C ( 3 pF) F 2R Z N F O G2 (2) Finally, since CS and CF set the high-frequency noise gain, determine CS using Equation 3 (solving for CS by using NG2 = 6): C N 1 C S G2 F (3) which gives CS = 15 pF. Both of these calculated values have been reduced slightly in Figure 51 to account for parasitics. The resulting closed-loop bandwidth is approximately equal to Equation 4. f 3dB ZO GBP (4) For the values shown in Figure 51, f–3 dB is approximately 149 MHz. This is less than that predicted by simply dividing the GBP product by NG1. The compensation network controls the bandwidth to a lower value, while providing the full slew rate at the output and an improved distortion performance due to increased loop gain at frequencies below NG1 × ZO. 20 Submit Documentation Feedback OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 APPLICATION INFORMATION (continued) LOW DISTORTION, LIMITED OUTPUT, ADC INPUT DRIVER Figure 52 shows a simple ADC driver that operates on a single supply, and gives excellent distortion performance. The limit voltages track the input range of the converter, completely protecting against input overdrive. Note that the limiting voltages have been set 100 mV above/below the corresponding reference voltage from the converter. This circuit also implements an improved distortion for an inverting gain of –2 using external compensation. VS = +5V 562Ω VH = +3.6V 0.1µF 1.4kΩ VS = +5V 102Ω +3.5V VS = +5V RSEL REFT 0.1µF 3 7 8 OPA699 6 24.9Ω 5 2 1.4kΩ ADS822 10-Bit 40MSPS IN 100pF 750Ω INT/EXT GND +1.5V VIN 18pF 10-Bit Data 4 REFB 1000pF 374Ω +VS 102Ω 4pF VL = +1.4V 0.1µF 562Ω S0038-02 Figure 52. Single Supply, Limiting ADC Input Driver LIMITED OUTPUT, DIFFERENTIAL ADC INPUT DRIVER Figure 53 shows a differential ADC driver that takes advantage of the OPA699 limiters to protect the input of the ADC. Two OPA699s are used. The first one is an inverting configuration at a gain of –2. The second one is in a noninverting configuration at a gain of +2. See the Low Gain Compensation for Improved SFDR section for a discussion of stability issues of the OPA699 operating at a gain less than four. Each amplifier is swinging 2 VPP providing a 4-VPP differential signal to drive the input of the ADC. Limiters have been set 100 mV away from the magnitude of each amplifier maximum signal to provide input protection for the ADC, while maintaining an acceptable distortion level. Submit Documentation Feedback 21 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 APPLICATION INFORMATION (continued) +5V +1.1V OPA699 -1.1V -5V 1kΩ 100Ω 10pF 24.9Ω 0.01µF IN 1kΩ +5V VCM 4VPP +1.1V VIN = 200mVPP ADC 24.9Ω 0.01µF 1kΩ IN OPA699 100Ω 10pF -1.1V -5V 900Ω 100Ω S0040-02 Figure 53. Single to Differential AC-Coupled, High Gain Output Limited ADC Driver PRECISION HALF-WAVE RECTIFIER Figure 54 shows a half-wave rectifier with outstanding precision and speed. VH (pin 8) defaults to 3.5 V typically if left open, while the negative limit is set to ground. The gain for the circuit in Figure 54 is set at +6. Figure 55 shows input and output for ±0.5 V 100-MHz input. +VS = +5V 50Ω Source 75Ω 2 7 VO = Open VIN 8 OPA699 6 VO 5 3 4 150Ω 750Ω -VS = -5V S0039-02 Figure 54. Precision Half-Wave Rectifier 22 Submit Documentation Feedback OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 APPLICATION INFORMATION (continued) 3.5 Output Input and Output Voltage (V) 3.0 2.5 2.0 1.5 1.0 0.5 0 -0.5 Input -1.0 Time (5ns/div) G048 Figure 55. 100-MHz Sinewave Rectified HIGH-SPEED Schmitt TRIGGER Figure 56 shows a high-speed Schmitt Trigger. The output levels are precisely defined and the switching time is exceptional. The output voltage swings between VH and VL. R2 402Ω R1 200Ω +2V VREF R3 200Ω VH OPA699 VOUT VL VIN -2V S0044-02 Figure 56. High-Speed Schmitt Trigger The circuit operates as follows. When the input voltage is less than VHL then the output is limiting at VH. When the input is greater than VHH, then the output is limiting at VL, with VHL and VHH defined as in Equation 5. V HL,HH R1 R2 R3 R1 R2 R3 V V ref OUT R1 R2 (5) Due to the inverting function realized by the Schmitt Trigger, VHL corresponds to VOUT = VH, and VHH corresponds to VOUT = VL. Figure 57 shows the Schmitt Trigger operating with VREF = +5 V. This gives us VHH = 2.4 V and VHL = 1.6 V. The propagation delay for the OPA699 in a Schmitt Trigger configuration is 4 ns from high-to-low and 4 ns from low-to-high. Submit Documentation Feedback 23 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 APPLICATION INFORMATION (continued) Input and Output Voltage (V) 4 3 2 1 0 VOUT -1 VIN -2 -3 -4 Time (10ns/div) G049 Figure 57. Schmitt Trigger Time Domain Response for a 10-MHz Sinewave DESIGN-IN TOOLS Applications Support The Texas Instruments Applications Department is available for design assistance at 1-972-644-5580. The Texas Instruments web site (www.ti.com) has the latest product data sheets and other design tools. Demonstration Boards A PC board is available to assist in the initial evaluation of circuit performance of the OPA699ID. It is available as an unpopulated PCB with descriptive documentation, and can be requested through the Texas Instruments web site. See the demonstration board literature for more information. The summary information for this board is shown in Table 1. Table 1. Evaluation Module Ordering Information PRODUCT PACKAGE BOARD PART NUMBER LITERATURE NUMBER OPA699ID SO-8 DEM-OPA-SO-1A SBOU009 OPERATING SUGGESTIONS Theory of Operation The OPA699 is a voltage-feedback, gain of +4 V/V stable op amp. The output voltage is limited to a range set by the voltage on the limiter pins (5 and 8). When the input tries to overdrive the output, the limiters take control of the output buffer. This action from the limiters avoids saturating any part of the signal path, giving quick overdrive recovery and excellent limiter accuracy at any signal gain. The limiters have a sharp transition from the linear region of operation to output limiting. This transition allows the limiter voltages to be set near (< 100 mV) the desired signal range. The distortion performance is also good near the limiter voltages. Output Limiters The output voltage is linearly dependent on the input(s) when it is between the limiter voltages VH (pin 8) and VL (pin 5). When the output tries to exceed VH or VL, the corresponding limiter buffer takes control of the output voltage and holds it at VH or VL. Because the limiters act on the output, their accuracy does not change with the gain. The transition from the linear region of operation to output limiting is sharp—the desired output signal can safely come to within 30 mV of VH or VL with no onset of non-linearity. The limiter voltages can be set to within 0.7 V of the supplies (VL = –VS + 0.7 V, VH = +VS– 0.7 V). They must also be at least 400 mV apart (VH– VL = 0.4 V). When pins 5 and 8 are left open, VH and VL go to the default voltage limit; the minimum values are given in the electrical specifications. Looking at Figure 58 for the zero bias current case shows the expected range of (VS– default limit voltages) = headroom. 24 Submit Documentation Feedback OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 Limiter Input Bias Current (µA) 100 75 Maximum Over Temperature 50 Minimum Over Temperature 25 0 -25 -50 Limiter Headroom = +VS - VH = VL - (-VS) Current = IVH or -IVL -75 -100 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Limiter Headroom (V) G027 Figure 58. Limit Bias Current vs Bias Voltage When the limiter voltages are more than 2.1 V from the supplies (VL = –VS + 2.1 V or VH = +VS– 2.1 V), you can use simple resistor dividers to set VH and VL (see Figure 47). Make sure to include the limiter input bias currents (see Figure 54) in the calculations (that is, IVL = 50 µA into pin 5, and IVH = +50 µA out of pin 8). For good limiter voltage accuracy, run a minimum 1-mA quiescent bias current through these resistors. When the limiter voltages need to be within 2.1 V of the supplies (VL = –VS + 2.1 V or VH = +VS– 2.1 V), consider using low impedance buffers to set VH and VL to minimize errors due to bias current uncertainty. This condition typically is the case for single-supply operation (VS = +5 V). Figure 48 runs 2.5 mA through the resistive divider that sets VH and VL. This limits errors due to IVH and IVL < ±1% of the target limit voltages. The limiters' dc accuracy depends on attention to detail. The two dominant error sources can be improved as follows: • Power supplies, when used to drive resistive dividers that set VH and VL, can contribute large errors (for example, ±5%). Using a more accurate source and bypassing pins 5 and 8 with good capacitors, improves limiter PSRR. • The resistor tolerances in the resistive divider can also dominate. Use 1% resistors. Other error sources also contribute, but should have little impact on the limiters' dc accuracy. • Reduce offsets caused by the limiter input bias currents. Select the resistors in the resistive divider(s) as described above. • Consider the signal path dc errors as contributing to uncertainty in the useable output swing. • The limiter offset voltage only slightly degrades limiter accuracy. Figure 59 shows how the limiters affect distortion performance. Virtually no degradation in linearity is observed for output voltage swinging right up to the limiter voltages. In this plot a fixed ±1-V output swing is driven while the limiter voltages are reduced symmetrically. Until the limiters are reduced to ±1.1 V, little distortion degradation is observed. Harmonic Distortion (dBc) -40 VO = 0VDC ± 1VP f = 5MHz RL = 500Ω -50 -60 2nd-Harmonic -70 3rd-Harmonic -80 -90 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 ± Limit Voltage (V) 2.0 G019 Figure 59. Harmonic Distortion Near Limit Voltages Submit Documentation Feedback 25 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 Output Drive The OPA699 has been optimized to drive 500-Ω loads, such as ADCs. It still performs well driving 100-Ω loads; the specifications are shown for the 500-Ω load. This makes the OPA699 an ideal choice for a wide range of high-frequency applications. Many high-speed applications, such as driving ADCs, require op amps with low output impedance. As shown in the typical performance curve Output Impedance vs Frequency, the OPA699 maintains low closed-loop output impedance over frequency. Closed-loop output impedance increases with frequency, since loop gain decreases with frequency. Thermal Considerations The OPA699 does not require heat sinking under most operating conditions. Maximum desired junction temperature sets a maximum allowed internal power dissipation as described below. In no case should the maximum junction temperature be allowed to exceed 150°C. The total internal power dissipation (PD) is the sum of quiescent power (PDQ) and the additional power dissipated in the output stage (PDL), while delivering load power. PDQ is simply the specified no-load supply current times the total supply voltage across the part. PDL depends on the required output signals and loads. For a grounded resistive load, and equal bipolar supplies, it is at maximum when the output is at 1/2 either supply voltage. In this condition, PDL = VS2/(4RL) where RL includes the feedback network loading. Note that it is the power in the output stage and not in the load, that determines internal power dissipation. The operating junction temperature is: TJ = TA + PD × θJA, where TA is the ambient temperature. For example, the maximum TJ for a OPA699ID with G = +6, RF = 750 Ω, RL = 500 Ω, and ±VS = ±5 V at the maximum TA = 85°C is calculated as: P (10 V 15.5 mA) 155 mW DQ (5V)2 P 19.4 mW DL 4 (500 900 ) P D 155 mW 19.4 mW 174.4 mW T 85oC 174.4 mW 125 oCW 107 oC J (6) This would be the maximum TJ from VO = ±2.5 VDC. Most applications will be at a lower output stage power and have a lower TJ. Care must be taken when operating at higher ambient temperatures. Capacitive Loads Capacitive loads, such as the input to ADCs, decreases the amplifier phase margin, which may cause high-frequency peaking or oscillations. Capacitive loads ≥2 pF should be isolated by connecting a small resistor in series with the output, as shown in Figure 60. Increasing the gain from +2 improves the capacitive drive capabilities due to increased phase margin. RG RF RS VO OPA699 RL RT CL RL is optional S0048-02 Figure 60. Driving Capacitive Loads 26 Submit Documentation Feedback OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 In general, capacitive loads should be minimized for optimum high-frequency performance. The capacitance of coax cable (29 pF/ft for RG-58) does not load the amplifier when the coaxial cable or transmission line is terminated in its characteristic impedance. Frequency Response Compensation The OPA699 is internally compensated to be +4 gain stable and has a nominal phase margin of 60° at a gain of +6. Phase margin and peaking improve at higher gains. Recall that an inverting gain of –5 is equivalent to a gain of +6 for bandwidth purposes (that is, noise gain = 6). Standard external compensation techniques work with this device. For example, in the inverting configuration, the bandwidth may be limited without modifying the inverting gain by placing a series RC network to ground on the inverting node. This has the effect of increasing the noise gain at high frequencies, which limits the bandwidth. For unity-gain stable amplifier applications, the OPA698 is recommended. In applications where a large feedback resistor is required, such as a photodiode transimpedance amplifier, the parasitic capacitance from the inverting input to ground causes peaking or oscillations. To compensate for this effect, connect a small capacitor in parallel with the feedback resistor. The bandwidth is limited by the pole that the feedback resistor and this capacitor create. In other high-gain applications, use a three-resistor Tee network to reduce the RC time constants set by the parasitic capacitances. Pulse Settling Time The OPA699 is capable of an extremely fast settling time in response to a pulse input. Frequency response flatness and phase linearity are needed to obtain the best settling times. For capacitive loads, such as an ADC, use the recommended RS in the typical performance curve Recommended RS vs Capacitive Load. Extremely fine-scale settling (0.01%) requires close attention to ground return current in the supply decoupling capacitors. The pulse settling characteristics, when recovering from overdrive, are extremely good as shown in the typical characteristics. Distortion The OPA699's distortion performance is specified for a 500-Ω load, such as an ADC. Driving loads with smaller resistance increases the distortion as illustrated in Figure 61. Remember to include the feedback network in the load resistance calculations. -55 2nd-Harmonic Harmonic Distortion (dBc) -60 VO = 2VPP f = 5MHz -65 -70 -75 3rd-Harmonic -80 -85 -90 See Figure 47 1k 100 Load Resistance (Ω) G013 Figure 61. 5-MHz Harmonic Distortion vs Load Resistance Noise Performance High slew rate, voltage-feedback op amps usually achieve their slew rate at the expense of a higher input noise voltage. The 4.1-nV/√Hz input voltage noise for the OPA699, however, is much lower than comparable amplifiers. The input-referred voltage noise and the two input-referred current noise terms, combine to give low output noise under a wide variety of operating conditions. Figure 62 shows the op amp noise analysis model with all the noise terms included. In this model, all noise terms are taken to be noise voltage or current density terms in either nV/√Hz or pA/√Hz. Submit Documentation Feedback 27 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 ENI EO OPA699 RS IBN ERS RF 4kTRS 4kT RG 4kTRF IBI RG 4kT = 1.6E -20J at 290 K S0049-02 Figure 62. Op Amp Noise Analysis Model The total output spot noise voltage can be computed as the square root of the sum of all squared output noise voltage contributors. Equation 7 shows the general form for the output noise voltage using the terms shown in Figure 62. E O E 2 NI BNRS 2 I 4kTR S BIRF 2 NG 2 I 4kTR NG F (7) Dividing this expression by the noise gain [NG = (1+RF/RG)] gives the equivalent input-referred spot noise voltage at the noninverting input, as shown in Equation 8. E N E 2 NI BNRS I 2 4kTR S I R BI F NG 2 4kTR F NG (8) Evaluating these two equations for the OPA699 circuit and component values (see Figure 47) gives a total output spot noise voltage of 27.4 nV/√Hz and a total equivalent input spot noise voltage of 4.6 nV/√Hz. This total input-referred spot noise voltage is only slightly higher than the 4.1-nV/√Hz specification for the op amp voltage noise alone. This is the case as long as the impedances appearing at each op amp input are limited to a maximum value of 300 Ω. Keeping both (RF || RG) and the noninverting input source impedance less than 300 Ω satisfies both noise and frequency response flatness considerations. Since the resistor-induced noise is negligible, additional capacitive decoupling across the bias current cancellation resistor (RT) for the inverting op amp configuration of Figure 49 is not required, but is still desirable. DC-Accurracy and Offset Control The balanced input stage of a wideband voltage feedback op amp allows good output dc accuracy in a large variety of applications. The power-supply current trim for the OPA699 gives even tighter control than comparable products. Although the high-speed input stage does require relatively high input bias current (typically 3 µA at each input terminal), the close matching between them may be used to reduce the output dc error caused by this current. The total output offset voltage may be considerably reduced by matching the dc source resistances appearing at the two inputs. This reduces the output dc error due to the input bias currents to the offset current times the feedback resistor. Evaluating the configuration of Figure 47, using worst-case +25°C input offset voltage and current specifications, gives a worst-case output offset voltage, with NG = noninverting signal gain, equal to: ±[NG × VIO(MAX)] ± [RF × IIO(MAX)] = ±(2 × 8 mV) ± (750 Ω × 3 µA) = ±18.3 mV 28 Submit Documentation Feedback OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 A fine-scale output offset null or dc operating point adjustment, is often required. Numerous techniques are available for introducing dc-offset control into an op amp circuit. Most of these techniques eventually reduce to adding a dc current through the feedback resistor. In selecting an offset trim method, one key consideration is the impact on the desired signal path frequency response. If the signal path is intended to be noninverting, the offset control is best applied as an inverting summing signal to avoid interaction with the signal source. If the signal path is intended to be inverting, applying the offset control to the noninverting input may be considered. However, the dc offset voltage on the summing junction sets up a dc current back into the source which must be considered. Applying an offset adjustment to the inverting op amp input can change the noise gain and frequency response flatness. For a dc-coupled inverting amplifier, Figure 63 shows one example of an offset adjustment technique that has minimal impact on the signal frequency response. In this case, the dc offsetting current is brought into the inverting input node through resistor values that are much larger than the signal path resistors. This insures that the adjustment circuit has minimal effect on the loop gain as well as the frequency response. +5V Supply Decoupling Not Shown 0.1µF 328Ω OPA699 VO -5V RG 150Ω +5V 5kΩ RF 750Ω VI 20kΩ ±200mV Output Adjustment 10kΩ 0.1µF 5kΩ VO VI =- RF RG = -5 S0050-02 -5V Figure 63. DC-Coupled, Inverting Gain of –5, With Offset Adjustment Board Layout Guidelines Achieving optimum performance with the high-frequency OPA699 requires careful attention to layout design and component selection. Recommended PCB layout techniques and component selection criteria are: 1. Minimize parasitic capacitance to any ac ground for all of the signal I/O pins. Open a window in the ground and power planes around the signal I/O pins, and leave the ground and power planes unbroken elsewhere. 2. Provide a high quality power supply. Use linear regulators, ground plane and power planes to provide power. Place high frequency 0.1-µF decoupling capacitors < 0.2" away from each power-supply pin. Use wide, short traces to connect to these capacitors to the ground and power planes. Also use larger (2.2 µF to 6.8 µF) high-frequency decoupling capacitors to bypass lower frequencies. They may be somewhat further from the device and be shared among several adjacent devices. 3. Place external components close to the OPA699. This minimizes inductance, ground loops, transmission line effects and propagation delay problems. Be extra careful with the feedback (RF), input and output resistors. 4. Use high-frequency components to minimize parasitic elements. Resistors should be a low reactance type. Surface-mount resistors work best and allow a tighter layout. Metal film or carbon composition axially-leaded resistors can also provide good performance when their leads are as short as possible. Never use wirewound resistors for high-frequency applications. Remember that most potentiometers have large parasitic capacitances and inductances. Multilayer ceramic chip capacitors work best and take up little space. Monolithic ceramic capacitors also work well. Use RF type capacitors with low ESR and ESL. The large power pin bypass capacitors (2.2 µF to 6.8 µF) should be tantalum for better high frequency and pulse performance. Submit Documentation Feedback 29 OPA699M www.ti.com SGLS289A – MAY 2005 – REVISED MARCH 2006 5. Choose low resistor values to minimize the time constant set by the resistor and its parasitic parallel capacitance. Good metal film or surface mount resistors have approximately 0.2-pF parasitic parallel capacitance. For resistors > 1.5 kΩ, this adds a pole and/or zero below 500 MHz. Make sure that the output loading is not too heavy. The recommended 750-Ω feedback resistor is a good starting point in most designs. 6. Use short direct traces to other wideband devices on the board. Short traces act as a lumped capacitive load. Wide traces (50 to 100 mils) should be used. Estimate the total capacitive load at the output and use the series isolation resistor recommended in the typical performance curve, Recommended RS vs Capacitive Load. Parasitic loads < 2 pF may not need the isolation resistor. 7. When long traces are necessary, use transmission line design techniques (consult an ECL design handbook for microstrip and stripline layout techniques). A 50-Ω transmission line is not required on board—a higher characteristic impedance helps reduce output loading. Use a matching series resistor at the output of the op amp to drive a transmission line and a matched load resistor at the other end to make the line appear as a resistor. If the 6 dB of attenuation that the matched load produces is not acceptable, and the line is not too long, use the series resistor at the source only. This isolates the source from the reactive load presented by the line, but the frequency response will be degraded. Multiple destination devices are best handled as separate transmission lines, each with its own series source and shunt load terminations. Any parasitic impedances acting on the terminating resistors alters the transmission line match and can cause unwanted signal reflections and reactive loading. 8. Do not use sockets for high-speed parts like the OPA699. The additional lead length and pin-to-pin capacitance introduced by the socket creates an extremely troublesome parasitic network. Best results are obtained by soldering the part onto the board. Power Supplies The OPA699 is nominally specified for operation using either ±5-V supplies or a single +5-V supply. The maximum specified total supply voltage of 12 V allows reasonable tolerances on the supplies. Higher supply voltages can break down internal junctions, possibly leading to catastrophic failure. Single-supply operation is possible as long as common mode voltage constraints are observed. The common-mode input and output voltage specifications can be interpreted as required headroom to the supply voltage. Observing this input and output headroom requirement allows a design of non-standard or single-supply operation circuits. Figure 48 shows one approach to single-supply operation. input and ESD protection The OPA699 is built using a high-speed complementary bipolar process. The internal junction breakdown voltages are relatively low for these small geometry devices. These breakdowns are reflected in the Absolute Maximum Ratings table. All device pins are protected with internal ESD protection diodes to the power supplies, as shown in Figure 64. These diodes provide moderate protection to input overdrive voltages above the supplies as well. The protection diodes can typically support 30-mA continuous current. Where higher currents are possible (e.g., in systems with ±15-V supply parts driving into the OPA699), 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. +V S External Pin Internal Circuitry -V S S0051-01 Figure 64. I/O Pin ESD Protection 30 Submit Documentation Feedback PACKAGE OPTION ADDENDUM www.ti.com 18-Sep-2008 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing OPA699MJD ACTIVE CDIP SB JD Pins Package Eco Plan (2) Qty 8 1 TBD Lead/Ball Finish MSL Peak Temp (3) POST-PLATE N / A for Pkg Type (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) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. 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