THS4281 www.ti.com SLOS432 – APRIL 2004 VERY LOW-POWER, HIGH-SPEED, RAIL-TO-RAIL INPUT AND OUTPUT VOLTAGE-FEEDBACK OPERATIONAL AMPLIFIER FEATURES • • • • • • • • • • • DESCRIPTION Very Low Quiescent Current: 750 µA (at 5 V) Rail-to-Rail Input and Output: – Common-Mode Input Voltage Extends 400 mV Beyond the Rails – Output Swings Within 150 mV From the Rails Wide -3 dB Bandwidth at 5 V: – 90-MHz @ Gain = +1, 40 MHz @ Gain = +2 High Slew Rate: 35 V/µs Fast Settling Time (2-V Step): – 78 ns to 0.1% – 150 ns to 0.01% Low Distortion @ Gain = +2, VO = 2-Vpp, 5 V: – -91 dBc at 100 kHz, -67 dBc at 1 MHz Input Offset Voltage: 2.5 mV (Max at 25°C) Output Current >30 mA (10-Ω Load, 5 V) Low Voltage Noise of 12.5 nV/√Hz Supply Voltages: +2.7 V, 3 V, +5 V, ±5 V, +15 V Packages: SOT-23, MSOP, and SOIC Fabricated using the BiCom-II process, the THS4281 is a low-power, rail-to-rail input and output voltage-feedback operational amplifier designed to operate over a wide power supply range of 2.7-V to 15-V single supply, and ±1.35-V to ±7.5-V dual supply. Consuming only 750 µA with a unity gain bandwidth of 90 MHz and a high 35-V/µs slew rate, the THS4281 allows portable or other power-sensitive applications to realize high performance with minimal power. To ensure long battery life in portable applications, the quiescent current is trimmed to be less than 900 µA at 25°C, and 1 mA from –40°C to 85°C. The THS4281 is a true single-supply amplifier with a specified common-mode input range of 400 mV beyond the rails. This allows for high-side current sensing applications without phase reversal concerns. Its output swings to within 40 mV from the rails with 10-kΩ loads, and 150 mV from the rails with 1-kΩ loads. The THS4281 has a good 0.1% settling time of 78 ns, and 0.01% settling time of 150 ns. The low THD of -87 dBc at 100 kHz, coupled with a maximum offset voltage of less than 2.5 mV, makes the THS4281 a good match for high-resolution ADCs sampling less than 2 MSPS. APPLICATIONS • • • • • Portable/Battery-Powered Applications High Channel Count Systems ADC Buffer Active Filters Current Sensing The THS4281 is offered in a space-saving SOT-23-5 package, a small MSOP-8 package, and the industry standard SOIC-8 package. 470 pF V BAT 500 I 2.5 k RSENSE V OUT = I RSENSE VBAT VBAT 0.2 − 500 + Load 100 470 pF THS4281 +IN ADS8320 −IN 10 nF 2.5 k VBAT/2 High-Side, Low Power Current-Sensing System 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. FilterPro is a trademark of Texas Instruments. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2004, Texas Instruments Incorporated THS4281 www.ti.com SLOS432 – APRIL 2004 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 (1) over operating free-air temperature range (unless otherwise noted) UNIT Supply voltage, VS- to VS+ 16.5 V ±VS± 0.5 V Input voltage, VI ±2 V Differential input voltage, VID ±100 mA Output current, IO Continuous power dissipation See Dissipation Rating Table Maximum junction temperature, any condition, (2) TJ Maximum junction temperature, continuous operation, long term 150°C reliability (2) TJ 125°C Storage temperature range, Tstg -65°C to 150°C Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds ESD ratings (1) (2) 300°C HBM 3500 V CDM 1500 V MM 100 V The absolute maximum ratings under any condition is limited by the constraints of the silicon process. Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not implied. The maximum junction temperature for continuous operation is limited by package constraints. Operation above this temperature may result in reduced reliability and/or lifetime of the device. recommended operating conditions. RECOMMENDED OPERATING CONDITIONS Supply voltage, (VS+ and VS -) Dual supply Single supply MIN MAX ±1.35 ±8.25 2.7 16.5 UNIT V DISSIPATION RATINGS TABLE PER PACKAGE θJC (°C/W) θJA (1) (°C/W) DBV (5) 55 D (8) 38.3 DGK (8) 71.5 PACKAGE (1) (2) 2 POWER RATING (2) TA < 25°C TA = 85°C 255.4 391 mW 156 mW 97.5 1.02 W 410 mW 180.8 553 mW 221 mW This data was taken using the JEDEC standard High-K test PCB. Power rating is determined with a junction temperature of 125°C. This is the point where distortion starts to substantially increase. Thermal management of the final PCB should strive to keep the junction temperature at or below 125°C for best performance and long term reliability. THS4281 www.ti.com SLOS432 – APRIL 2004 PACKAGING/ORDERING INFORMATION PACKAGED DEVICES DEVICE MARKING PACKAGE TYPE AON SOT-23 - 5 -- SOIC - 8 AOO MSOP - 8 THS4281DBVT THS4281DBVR THS4281D THS4281DR THS4281DGK THS4281DGKR TRANSPORT MEDIA, QUANTITY Tape and Reel, 250 Tape and Reel, 3000 Rails, 75 Tape and Reel, 2500 Rails, 75 Tape and Reel, 2500 PIN CONFIGURATION TOP VIEW DBV TOP VIEW D and DGK THS4281 VOUT 1 VS− 2 IN+ 3 5 4 THS4281 VS+ NC 1 8 NC IN− 2 7 VS+ IN+ 3 6 VOUT VS− 4 5 NC IN− NOTE: NC indicates there is no internal connection to these pins. 3 THS4281 www.ti.com SLOS432 – APRIL 2004 ELECTRICAL CHARACTERISTICS, VS = 3 V (VS+ = 3 V, VS- = GND) G = +2, RF = 2.49 kΩ, RL = 1 kΩ to 1.5 V, unless otherwise noted TYP PARAMETER CONDITIONS OVER TEMPERATURE UNITS MIN/ MAX 83 MHz Typ G = +2, VO = 100 mVpp, RF = 1.65 kΩ 40 MHz Typ G = +5, VO = 100 mVpp, RF = 1.65 kΩ 8 MHz Typ G = +10, VO = 100 mVpp, RF = 1.65 kΩ 3.8 MHz Typ 20 MHz Typ 25°C 25°C 0°C to 70°C -40°C to 85°C AC PERFORMANCE G = +1, VO = 100 mVpp, RF = 34 Ω Small-Signal Bandwidth 0.1 dB Flat Bandwidth G = +2, VO = 100 mVpp, RF = 1.65 kΩ Full-Power Bandwidth G = +2, VO = 2 Vpp 8 MHz Typ G = +1, VO = 2-V Step 26 V/µs Typ G = -1, VO = 2-V Step 27 V/µs Typ Slew Rate Settling time to 0.1% G = -1, VO = 1-V Step 80 ns Typ Settling time to 0.01% G = -1, VO = 1-V Step 155 ns Typ Rise/Fall Times G = +1, VO = 2-V Step 55 ns Typ Harmonic Distortion G = +2, VO = 2 Vpp -52 dBc Typ -52 dBc Typ -69 dBc Typ -71 dBc Typ VO = 1 Vpp, f = 10 kHz 0.003 % Typ VO = 2 Vpp, f = 10 kHz 0.03 % Typ 0.05/0.08 % Typ 0.25/0.35 ° Typ Second Harmonic Distortion Third Harmonic Distortion Second Harmonic Distortion Third Harmonic Distortion THD + N Differential Gain (NTSC/PAL) Differential Phase (NTSC/PAL) f = 1 MHz, RL = 1 kΩ f = 100 kHz, RL = 1 kΩ G = +2, RL = 150 Ω Input Voltage Noise f = 100 kHz 12.5 nA/√Hz Typ Input Current Noise f = 100 kHz 1.5 pA/√Hz Typ Open-Loop Voltage Gain (AOL) 95 dB Typ Input Offset Voltage 0.5 Max DC PERFORMANCE 2.5 Average Offset Voltage Drift Input Bias Current Average Bias Current Drift VCM = 1.5 V Input Offset Current 0.5 0.1 0.8 0.4 Average Offset Current Drift 3.5 3.5 mV ±7 ±7 µV/°C Typ 1 1 µA Max ±2 ±2 nA/°C Typ 0.5 0.5 µA Max ±2 ±2 nA/°C Typ Min INPUT CHARACTERISTICS Common-Mode Input Range -0.4/3.4 -0.3/3.3 -0.1/3.1 -0.1/3.1 V Common-Mode Rejection Ratio VCM = 0 V to 3 V 92 75 70 70 dB Min Input Resistance Common-mode 100 MΩ Typ Input Capacitance Common-mode/Differential 0.8/1.2 pF Typ 4 THS4281 www.ti.com SLOS432 – APRIL 2004 ELECTRICAL CHARACTERISTICS, VS = 3 V (VS+ = 3 V, VS- = GND) (continued) G = +2, RF = 2.49 kΩ, RL = 1 kΩ to 1.5 V, unless otherwise noted TYP PARAMETER CONDITIONS 25°C OVER TEMPERATURE 25°C 0°C to 70°C -40°C to 85°C UNITS MIN/ MAX V Typ OUTPUT CHARACTERISTICS Output Voltage Swing RL = 10 kΩ 0.04/2.96 RL = 1 kΩ 0.1/2.9 0.14/2.86 0.2/2.8 0.2/2.8 V Min Output Current (Sourcing) RL = 10 Ω 23 18 15 15 mA Min Output Current (Sinking) RL = 10 Ω 29 22 19 19 mA Min Output Impedance f = 1 MHz 1 Ω Typ POWER SUPPLY Maximum Operating Voltage 3 16.5 16.5 16.5 V Max Minimum Operating Voltage 3 2.7 2.7 2.7 V Min Maximum Quiescent Current 0.75 0.9 0.98 1.0 mA Max Minimum Quiescent Current 0.75 0.6 0.57 0.55 mA Min Power Supply Rejection (+PSRR) VS+ = 3.25 V to 2.75 V, VS- = 0 V 90 70 65 65 dB Min Power Supply Rejection (-PSRR) VS+ = 3 V, VS- = 0 V to 0.65 V 90 70 65 65 dB Min 5 THS4281 www.ti.com SLOS432 – APRIL 2004 ELECTRICAL CHARACTERISTICS, VS = 5 V (VS+ = 5 V, VS- = GND) G = +2, RF = 2.49 kΩ, RL = 1 kΩ to 2.5 V, unless otherwise noted TYP PARAMETER CONDITIONS 25°C OVER TEMPERATURE 25°C 0°C to 70°C -40°C to 85°C UNITS MIN/ MAX AC PERFORMANCE G = +1, VO = 100 mVpp, RF = 34 Ω 90 MHz Typ G = +2, VO = 100 mVpp, RF = 2 kΩ 40 MHz Typ G = +5, VO = 100 mVpp, RF = 2 kΩ 8 MHz Typ G = +10, VO = 100 mVpp, RF = 2 kΩ 3.8 MHz Typ 0.1-dB Flat Bandwidth G = +2, VO = 100 mVpp, RF = 2 kΩ 20 MHz Typ Full-Power Bandwidth G = +2, VO = 2 Vpp 9 MHz Typ G = +1, VO = 2-V Step 31 V/µs Typ G = -1, VO = 2-V Step 34 V/µs Typ Small-Signal Bandwidth Slew Rate Settling Time to 0.1% G = -1, VO = 2-V Step 78 ns Typ Settling Time to 0.01% G = -1, VO = 2-V Step 150 ns Typ Rise/Fall Times G = +1, VO = 2-V Step 48 ns Typ Harmonic Distortion G = +2, VO = 2 Vpp -67 dBc Typ -76 dBc Typ Second Harmonic Distortion Third Harmonic Distortion Second Harmonic Distortion Third Harmonic Distortion THD + N Differential Gain (NTSC/PAL) Differential Phase (NTSC/PAL) f = 1 MHz, RL = 1 kΩ -92 dBc Typ -106 dBc Typ VO = 2 Vpp, f = 10 kHz 0.0009 % Typ VO = 4 Vpp, f = 10 kHz 0.0005 % Typ 0.11/0.17 % Typ 0.11/0.14 ° Typ f = 100 kHz, RL = 1 kΩ G = +2, RL = 150 Ω Input Voltage Noise f = 100 kHz 12.5 nV/√Hz Typ Input Current Noise f = 100 kHz 1.5 pA/√Hz Typ dB Min Max DC PERFORMANCE Open-Loop Voltage Gain (AOL) 105 85 80 80 Input Offset Voltage 0.5 2.5 3.5 3.5 mV ±7 ±7 µV/°C Typ 1 1 µA Max ±2 ±2 nA/°C Typ 0.5 0.5 µA Max ±2 ±2 nA/°C Typ Average Offset Voltage Drift Input Bias Current Average Bias Current Drift Input Offset Current Average Offset Current Drift 6 VCM = 2.5 V 0.5 0.1 0.8 0.4 THS4281 www.ti.com SLOS432 – APRIL 2004 ELECTRICAL CHARACTERISTICS, VS = 5 V (VS+ = 5 V, VS- = GND) (continued) G = +2, RF = 2.49 kΩ, RL = 1 kΩ to 2.5 V, unless otherwise noted TYP PARAMETER CONDITIONS OVER TEMPERATURE 25°C 25°C 0°C to 70°C -40°C to 85°C UNITS MIN/ MAX -0.4/5.4 -0.3/5.3 -0.1/5.1 -0.1/5.1 V Min 85 80 80 INPUT CHARACTERISTICS Common-Mode Input Range Common-Mode Rejection Ratio VCM = 0 V to 5 V 100 dB Min Input Resistance Common-mode 100 MΩ Typ Input Capacitance Common-mode/Differential 0.8/1.2 pF Typ V Typ V Min Min OUTPUT CHARACTERISTICS RL = 10 kΩ 0.04/4.96 RL = 1 kΩ 0.15/4.85 0.2/4.8 Output Current (Sourcing) RL = 10 Ω 33 24 20 20 mA Output Current (Sinking) RL = 10 Ω 44 30 25 25 mA Min Output Impedance f = 1 MHz 1 Ω Typ Max Output Voltage Swing 0.25/4.75 0.25/4.75 POWER SUPPLY Maximum Operating Voltage 5 16.5 16.5 16.5 V Minimum Operating Voltage 5 2.7 2.7 2.7 V Min Maximum Quiescent Current 0.75 0.9 0.98 1.0 mA Max Minimum Quiescent Current 0.75 0.6 0.57 0.55 mA Min Power Supply Rejection (+PSRR) VS+ = 5.5 V to 4.5 V, VS- = 0 V 100 80 75 75 dB Min Power Supply Rejection (-PSRR) VS+ = 5 V, VS- = 0 V to 1.0 V 100 80 75 75 dB Min 7 THS4281 www.ti.com SLOS432 – APRIL 2004 ELECTRICAL CHARACTERISTICS, VS = ±5 V G = +2, RF = 2.49 kΩ, RL = 1 kΩ, unless otherwise noted TYP PARAMETER CONDITIONS 25°C OVER TEMPERATURE 25°C 0°C to 70°C -40°C to 85°C UNITS MIN/ MAX AC PERFORMANCE G = +1, VO = 100 mVpp, RF = 34 Ω 95 MHz Typ G = +2, VO = 100 mVpp 40 MHz Typ G = +5, VO = 100 mVpp 8 MHz Typ G = +10, VO = 100 mVpp 3.8 MHz Typ 0.1-dB Flat Bandwidth G = +2, VO = 100 mVpp 20 MHz Typ Full-Power Bandwidth G = +1, VO = 2 Vpp 9.5 MHz Typ G = +1, VO = 2-V Step 35 V/µs Typ G = -1, VO = 2-V Step 35 V/µs Typ Small-Signal Bandwidth Slew Rate Settling Time to 0.1% G = -1, VO = 2-V Step 78 ns Typ Settling Time to 0.01% G = -1, VO = 2-V Step 140 ns Typ Rise/Fall Times G = +1, VO = 2-V Step 45 ns Typ Harmonic Distortion G = +2, VO = 2 Vpp -69 dBc Typ -76 dBc Typ -93 dBc Typ Second Harmonic Distortion Third Harmonic Distortion Second Harmonic Distortion Third Harmonic Distortion THD + N Differential Gain (NTSC/PAL) Differential Phase (NTSC/PAL) f = 1 MHz, RL = 1 kΩ f = 100 kHz, RL = 1 kΩ -107 dBc Typ VO = 2 Vpp, f = 10 kHz 0.0009 % Typ VO = 8 Vpp, f = 10 kHz 0.0003 % Typ 0.03/0.03 % Typ 0.08/0.1 ° Typ G = +2, RL = 150 Ω Input Voltage Noise f = 100 kHz 12.5 nV/√Hz Typ Input Current Noise f = 100 kHz 1.5 pA/√Hz Typ DC PERFORMANCE Open-Loop Voltage Gain (AOL) 108 90 85 85 dB Min Input Offset Voltage 0.5 2.5 3.5 3.5 mV Max ±7 ±7 µV/°C Typ 0.5 0.8 1 1 µA Max ±2 ±2 nA/°C Typ 0.5 0.5 µA Max ±2 ±2 nA/°C Typ V Min Average Offset Voltage Drift Input Bias Current Average Bias Current Drift VCM = 0 V Input Offset Current 0.1 0.4 Average Offset Current Drift INPUT CHARACTERISTICS Common-Mode Input Range ±5.4 ±5.3 ±5.1 ±5.1 90 85 85 Common-Mode Rejection Ratio VCM = -5 V to +5 V 107 dB Min Input Resistance Common-mode 100 MΩ Typ Input Capacitance Common-mode / Differential 0.8/1.2 pF Typ RL = 10 kΩ ±4.93 V Typ RL = 1 kΩ ±4.8 ±4.6 ±4.5 ±4.5 V Min Output Current (Sourcing) RL = 10 Ω 48 35 30 30 mA Min Output Current (Sinking) RL = 10 Ω 60 45 40 40 mA Min Output Impedance f = 1 MHz 1 Ω Typ OUTPUT CHARACTERISTICS Output Voltage Swing 8 THS4281 www.ti.com SLOS432 – APRIL 2004 ELECTRICAL CHARACTERISTICS, VS = ±5 V (continued) G = +2, RF = 2.49 kΩ, RL = 1 kΩ, unless otherwise noted TYP PARAMETER CONDITIONS OVER TEMPERATURE 25°C 25°C 0°C to 70°C -40°C to 85°C UNITS MIN/ MAX ±5 ±8.25 ±8.25 ±8.25 V Max Minimum Operating Voltage ±5 ±1.35 ±1.35 ±1.35 V Min Maximum Quiescent Current 0.8 0.93 1.0 1.05 mA Max POWER SUPPLY Maximum Operating Voltage Minimum Quiescent Current 0.8 0.67 0.62 0.6 mA Min Power Supply Rejection (+PSRR) VS+ = 5.5 V to 4.5 V, VS- = 5.0 V 100 80 75 75 dB Min Power Supply Rejection (-PSRR) VS+ = 5 V, VS- = -5.5 V to -4.5 V 100 80 75 75 dB Min 9 THS4281 www.ti.com SLOS432 – APRIL 2004 TYPICAL CHARACTERISTICS 1000 900 TA = 25°C 800 TA = −40°C 700 600 500 3 4 5 6 7 8 0.5 0 −0.5 −1 VS = 5 V −1.5 VS = 3 V −2 −2.5 9 10 11 12 13 14 15 −0.5 −1 −1.5 −2 1 2 3 4 5 6 VICR − Common-Mode Input Voltage − V Figure 2. Figure 3. (VS = 15 V) INPUT OFFSET VOLTAGE vs COMMON-MODE INPUT VOLTAGE POSITIVE VOLTAGE HEADROOM vs SOURCE CURRENT NEGATIVE VOLTAGE HEADROOM vs SINK CURRENT 4 4 Load Tied to VS/2 0 −0.5 −1 −1.5 −2 Load Tied to VS/2 ±5 V 3.5 3 − Voltage Headroom − (Vout − Vs−) + Voltage Headroom − (Vs+ − Vout) VS = 15 V 0.5 15 V 2.5 2 5V 1.5 1 0.5 0 −1 0 2 4 6 8 10 12 14 16 VICR − Common-Mode Input Voltage − V 20 30 40 50 2 5V 1.5 1 0.5 60 0 10 20 30 40 50 Figure 4. Figure 5. Figure 6. (VS = 5 V) OUTPUT VOLTAGE vs LOAD RESISTANCE (VS = ±5 V) OUTPUT VOLTAGE vs LOAD RESISTANCE (VS = 15 V) OUTPUT VOLTAGE vs LOAD RESISTANCE 4 VS = ±5 V Load Tied to GND 3 VS = 5 V Load Tied to VS/2 3 2.5 2 1.5 1 VO − Output Voltage − V 5 2 1 0 −1 −2 −3 −4 0.5 −5 0 10 15 V 2.5 −Iout − Sink Current − mA 5 3.5 10 ±5 V 3 +Iout − Source Current − mA 4.5 4 3.5 0 0 VO − Output Voltage − V V OS − Input Offset Voltage − mV 0 Figure 1. 1 VO − Output Voltage − V VS = ±5 V 0.5 −2.5 −6 −5 −4 −3 −2 −1 0 −1 0 1 2 3 4 5 6 VICR − Common-Mode Input Voltage − V VCC − Supply Voltage − V 100 1k RL − Load Resistance − Ω Figure 7. 10 V OS − Input Offset Voltage − mV V OS − Input Offset Voltage − mV I Q − Quiescent Current −µ A 1 1 TA = 85°C −2.5 (VS = ±5 V) INPUT OFFSET VOLTAGE vs COMMON-MODE INPUT VOLTAGE (VS = 3 V, VS = 5 V) INPUT OFFSET VOLTAGE vs COMMON-MODE INPUT VOLTAGE QUIESCENT CURRENT vs SUPPLY VOLTAGE 10 k 10 100 1k RL − Load Resistance − Ω Figure 8. 10 k 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 60 VS = 15 V Load Tied to VS/2 10 100 1k RL − Load Resistance − Ω Figure 9. 10 k THS4281 www.ti.com SLOS432 – APRIL 2004 TYPICAL CHARACTERISTICS (continued) (VS = 2.7 V) FREQUENCY RESPONSE FREQUENCY RESPONSE 9 6 RF = 4 kΩ 6 3 VS = 5 V 2 RF = 4 kΩ VS = 2.7 V VS = ±5 V 1 0 6 Signal Gain − dB 4 9 VS = 15 V Signal Gain − dB Gain = 1, RF = 34 Ω, RL = 1 kΩ, VO = 100 mVPP 5 Signal Gain − dB (VS = 3 V) FREQUENCY RESPONSE RF = 1.65 kΩ RF = 1 kΩ 3 RF = 1.65 kΩ RF = 1 kΩ 3 −1 0 VS = 2.7 V Gain = 2, RL = 1 kΩ, VO = 0.1 VPP −2 −3 −4 0 −3 1 10 0.1 100 1 10 f − Frequency − MHz f − Frequency − MHz VS = 3 V Gain = 2, RL = 1 kΩ, VO = 0.1 VPP −3 0.1 100 1 10 Figure 10. Figure 11. Figure 12. (VS = 5 V) FREQUENCY RESPONSE (VS = ±5 V) FREQUENCY RESPONSE (VS = 2.7 V, VS = 3 V) 0.1-dB FREQUENCY RESPONSE 9 9 6.2 RF = 2 kΩ RF = 4 kΩ RF = 4 kΩ RF = 1 kΩ 3 −3 0.1 3 VS = ± 5 V, Gain = 2, RL = 1 kΩ, VO = 0.1 VPP 0.1 100 5.8 5.7 5.6 5.5 1 10 f − Frequency − MHz VS = 3 V Gain = 2, RF = 1.65 kΩ, RL = 1 kΩ, VO = 0.1 VPP 5.4 0.1 100 1 10 Figure 15. (VS = 5 V, ±5 V, 15 V) 0.1-dB FREQUENCY RESPONSE (VS = 2.7 V) FREQUENCY RESPONSE (VS = 3 V) FREQUENCY RESPONSE 24 20 VS = 5 V 5.8 5.7 1 10 f − Frequency − MHz Figure 16. G=5 12 8 G=2 4 Gain = 2, RF = 2 kΩ (VS = 5 V), RF = 2.49 kΩ (VS = ±5 V, 15 V), RL = 1 kΩ, VO = 0.1 VPP 5.4 0.1 16 16 G=5 12 8 G=2 4 G = −1 G = −1 0 0 −4 100 VS = 3V, RF = 1.65 kΩ, RL = 1 kΩ, VO = 0.1 VPP G = 10 20 Signal Gain − dB Signal Gain − dB VS = ± 5 V 5.9 24 VS = 2.7 V, RF = 1.65 kΩ, RL = 1 kΩ, VO = 0.1 VPP G = 10 VS = 15 V 100 f − Frequency − MHz Figure 14. 6 Signal Gain − dB RF = 1 kΩ 5.9 Figure 13. 6.1 5.5 6 RF = 2.49 kΩ −3 1 10 f − Frequency − MHz 6.2 5.6 6 0 VS = 5 V Gain = 2, RL = 1 kΩ, VO = 0.1 VPP VS = 2.7 V 6.1 Signal Gain − dB Signal Gain − dB Signal Gain − dB 6 0 100 f − Frequency − MHz 0.1 1 10 f − Frequency − MHz Figure 17. 100 −4 0.1 1 10 100 f − Frequency − MHz Figure 18. 11 THS4281 www.ti.com SLOS432 – APRIL 2004 TYPICAL CHARACTERISTICS (continued) (VS = ±5 V) FREQUENCY RESPONSE (VS = 5 V) FREQUENCY RESPONSE 24 Signal Gain − dB Signal Gain − dB 20 G=5 12 G=2 8 4 16 12 G=2 8 12 G=2 8 4 G = −1 0 1 10 0 −4 0.1 100 −4 1 10 f − Frequency − MHz f − Frequency − MHz 100 0.1 Figure 21. (VS = 2.7 V) LARGE-SIGNAL FREQUENCY RESPONSE (VS = 5 V) LARGE-SIGNAL FREQUENCY RESPONSE (VS = ±5 V) LARGE-SIGNAL FREQUENCY RESPONSE 1 1 1 0.5 0.5 VO = 500 mVPP VO = 500 mVPP −1 VO = 1 VPP −2 VO = 2 VPP −4 −1.5 −2 VO = 2 VPP Gain = 1, RF = 34 Ω, RL = 1 kΩ, VS = 5 V −3.5 VO = 2 VPP −3 Gain = 1, RF = 34 Ω, RL = 1 kΩ, VS = ± 5 V −3.5 −4 1 10 1 100 10 f − Frequency − MHz 100 f − Frequency − MHz Figure 24. OPEN-LOOP GAIN vs FREQUENCY OUTPUT IMPEDANCE vs FREQUENCY REJECTION RATIO vs FREQUENCY 50 Gain 80 0 −25 70 −50 60 −75 Phase −100 40 −125 30 −150 20 −175 10 −200 0 −10 −225 1k −250 10k 100k 1 M 10 M 100 M f − Frequency − Hz Z o − Output Impedance − Ω 90 110 1000 25 Phase − ° RL = 1 kΩ, VS = ±5 V 100 −2 Figure 23. 110 10 VO = 1 VPP −1.5 Figure 22. 100 1 −1 −4 100 f − Frequency − MHz 50 −0.5 −2.5 −3 10 1 VO = 1 VPP −1 100 Gain = 1 RF = 2.5 kΩ VS = 5 V, ± 5 V, 15 V 90 10 1 0.1 CMRR 80 PSRR+ 70 60 50 PSRR− 40 30 20 10 0.01 100 k 0 1M 10 M 100 M f − Frequency − Hz Figure 25. VS = 15 V and 5 V 100 Rejection Ratios − dB −3.5 −0.5 −2.5 Gain = 1, RF = 34 Ω, RL = 1 kΩ, VS = 2.7 V −3 Signal Gain − dB Signal Gain − dB −0.5 VO = 500 mVPP 0 0 −2.5 100 Figure 20. 0.5 −1.5 1 10 f − Frequency − MHz Figure 19. 0 Signal Gain − dB G=5 G = −1 −4 0.1 Open-Loop Gain − dB 16 4 0 VS = 15 V, RF = 2.49 kΩ, RL = 1 kΩ, VO = 0.1 VPP G = 10 20 G=5 G = −1 12 24 VS = ±5 V, RF = 2.49 kΩ, RL = 1 kΩ, VO = 0.1 VPP G = 10 Signal Gain − dB 20 16 24 VS = 5 V, RF = 2 kΩ, RL = 1 kΩ, VO = 0.1 VPP G = 10 (VS = 15 V) FREQUENCY RESPONSE Figure 26. 1G 1k 10 k 100 k 1M f − Frequency − Hz Figure 27. 10 M 100 M THS4281 www.ti.com SLOS432 – APRIL 2004 TYPICAL CHARACTERISTICS (continued) NOISE vs FREQUENCY Vn 12.5 nV/rt(Hz) In 10 1.5 pA/rt(Hz) 60 Gain = −1, RF = 3 kΩ, RL = 1 kΩ, VS = 2.7 V 40 Gain = −1, RF = 3 kΩ, RL = 1 kΩ, VS = 5 V 50 Fall SR − Slew Rate − V/ µ s 100 (VS = 5 V) SLEW RATE 50 VS = 2.7 V to 15 V, TA = 27°C SR − Slew Rate − V/ µ s I n − Current Noise − pA/ Hz V n − Voltage Noise − nV/ Hz 1000 (VS = 2.7 V) SLEW RATE 30 Rise 20 10 40 Fall Rise 30 20 10 1 10 100 1K 10K 100K 0 f − Frequency − Hz 0.5 0.75 1 1.25 1.5 1.75 0 0.5 2 1 VO − Output Voltage − VPP (VS = ±5 V) SLEW RATE (VS = 15 V) SLEW RATE (VS = ±1.35 V) SETTLING TIME Fall Rise 30 20 Rise 100 80 Fall 60 40 Gain = −1 RL = 1 kΩ RF= 3 kΩ VS = ±1.35 V 1-V Step 0 −0.2 Fall 20 0 1.5 2 2.5 3 3.5 4 4.5 5 −0.6 0 VO − Output Voltage − VPP 1 2 3 4 5 6 7 8 9 10 11 12 VO − Output Voltage − VPP 0 20 40 60 Figure 32. Figure 33. (VS = ±1.35 V) SETTLING TIME (VS = ±2.5 V) SETTLING TIME (VS = ±2.5 V) SETTLING TIME 0.6 Fall 0.4 Gain = −1 RL = 1 kΩ RF= 3 kΩ VS = ±1.35 V 1-V Step 0.2 0 −0.2 −0.4 −0.6 1.5 1 1 0.8 Gain = −1 RL = 1 kΩ RF = 3 kΩ VS = ±2.5 V 0.5 0 100 Gain = −1 RL = 1 kΩ RF = 3 kΩ VS = ±2.5 V 2-V Step 0.6 % Error Rise VO − Output Voltage − V 1 80 t − Time − ns Figure 31. 0.8 % Error 0.2 −0.4 10 4 Rise 0.4 120 VO − Output Voltage − V SR − Slew Rate − V/µ s SR − Slew Rate − V/ µ s Gain = −1, RF = 3 kΩ, RL = 1 kΩ, VS = 15 V 140 40 3.5 0.6 160 1 3 Figure 30. Gain = −1, RF = 3 kΩ, RL = 1 kΩ, VS = ±5 V 0.5 2.5 Figure 29. 50 0 2 Figure 28. 70 60 1.5 VO − Output Voltage − VPP 0.4 0.2 Fall −0.5 0 −1 −0.2 −0.8 Rise −1 20 40 60 80 100 120 140 160 180 t − Time − ns Figure 34. −1.5 0 10 20 30 40 50 60 70 80 90 100 t − Time − ns Figure 35. −0.4 40 60 80 100 120 140 160 180 200 t − Time − ns Figure 36. 13 THS4281 www.ti.com SLOS432 – APRIL 2004 TYPICAL CHARACTERISTICS (continued) (VS = ±5 V) SETTLING TIME (VS = ±5 V) SETTLING TIME −30 1 Gain = −1 RL = 1 kΩ RF = 3 kΩ VS = ±5 V 2-V Step 0.8 1 0.6 0 % Error Gain = −1 RL = 1 kΩ RF= 3 kΩ VS = ±5 V 0.5 0.4 0.2 Rise −0.5 0 −1 −0.2 10 60 80 (Gain = +2) HARMONIC DISTORTION vs FREQUENCY −90 −30 −80 VS = 3.3 V, 2 VPP, HD2 −85 VS = ±5 V, 15 V HD2 −80 VS = 5 V,±5 V, 15 V HD3 −100 −90 VS = 3 V, 1 VPP, HD2 −100 VS = 3 V, 1 VPP, HD3 −105 −110 VS = 3.3 V, 1 VPP, HD2 −115 −120 VS = 3.3 V, 1 VPP, HD3 1 10 100 f − Frequency − MHz −90 VS = 2.7 V, HD3 −100 VS = 5 V ±5 V, 15 V HD2 −110 VS = 5 V ±5 V, 15 V HD3 10 k 20 k 1k 10 k 100 k f − Frequency − Hz 1M Figure 42. (Gain = +2) HARMONIC DISTORTION vs FREQUENCY HARMONIC DISTORTION vs LOAD RESISTANCE (VS = 2.7 V, 5 V) HARMONIC DISTORTION vs OUTPUT VOLTAGE VS = 2.7 V, 3 V, HD2 VS = 3 V, HD3 VS = 2.7 V, HD3 VS = 5 V ±5 V, 15 V HD2 1k 10 k 100 k f − Frequency − Hz Figure 43. 1M VS = 3 V, 2 VPP, HD3 −90 VS = 3 V, 1 VPP, HD2 −70 −100 VS = 3 V, 1 VPP, HD3 VS = 5V and ±5V, 2VPP, HD3 −120 VS = 5 V ±5 V, 15 V HD3 −120 VS = 3 V, 2 VPP, HD2 −80 −110 10 M 1k Gain = 2, RL = 1 kΩ, to VS/2, f = 10 kHz VS = 2.7 V, HD2 −80 −90 −100 −110 VS = 2.7 V, HD3 VS = 5 V, HD2 −120 VS = 5 V, and ±5 V, 2 VPP, HD2 −130 100 10 M −60 Gain = 2 f = 10 khz Harmonic Distortion − dBc −70 Harmonic Distortion − dBc Harmonic Distortion − dBc −80 Figure 41. −60 −130 100 VS = 2.7 V, HD2 −130 100 −60 −110 −70 Figure 40. VO = 2 VPP, Gain = 2, RL = 1 kΩ, to VS/2 −100 −60 f − Frequency − Hz −30 14 1k −50 −120 Gain = 2, RL = 1 kΩ, to VS/2 −130 10 VO = 1 VPP, Gain = 2, RL = 1 kΩ, to VS/2 −40 VS = 3.3 V, 2 VPP, HD3 −95 −125 −110 0.1 −90 10 (VS = 3 V, 3.3 V) HARMONIC DISTORTION vs FREQUENCY −70 −80 1 f − Frequency − MHz (Gain = +1) HARMONIC DISTORTION vs FREQUENCY VS = 5 V, HD2 −70 0.1 Figure 39. −60 −50 VS = 5 V,±5 V, 15 V HD3 Figure 38. VS = 2.7 V, HD3 −40 −90 Figure 37. Harmonic Distortion − dBc Harmonic Distortion − dBc −50 VS = ±5 V, 15 V HD2 −80 t − Time − ns VO = 2 VPP, Gain = 1, RL = 1 kΩ, to VS/2 VS = 2.7 V, HD2 −40 −70 100 120 140 160 180 200 t − Time − ns −30 VS = 2.7 V, HD3 VS = 5 V, HD2 −60 −110 −0.4 40 20 30 40 50 60 70 80 90 100 Harmonic Distortion − dBc 0 −50 −100 Fall −1.5 VO = 1 VPP, Gain = 1, RL = 1 kΩ, to VS/2 VS = 2.7 V, HD2 −40 Harmonic Distortion − dBc 1.5 VO − Output Voltage − V (Gain = +1) HARMONIC DISTORTION vs FREQUENCY VS = 5 V, HD3 10 k RL − Load Resistance − Figure 44. 100 k −130 0.1 1 VO − Output Voltage − VPP Figure 45. 10 THS4281 www.ti.com SLOS432 – APRIL 2004 TYPICAL CHARACTERISTICS (continued) (VS = 3 V, ±5 V) HARMONIC DISTORTION vs OUTPUT VOLTAGE −70 −80 −90 VS = 3 V, HD3 −100 VS = ±5 V, HD2 −110 Gain = 2, RL = 1 kΩ, to VS/2, f = 10 kHz −80 −90 −100 VS = 3.3 V, HD2 −110 VS =15 V, HD2 −120 −120 VS = ±5 V, HD3 VS = 15 V, HD3 −130 −130 0.1 1 VO − Output Voltage − VPP 0.1 10 1 10 20 0.100 VO = 2.5 VPP VO = 2 VPP VO = 1 VPP VO = 0.5 VPP 0.010 VS = 2.7 V, Bandwidth = 600 kHz, Gain = 2, RF = 2 kΩ, RL = 1 kΩ to VS/2 0.001 10 VO − Output Voltage − VPP 100 1k 10 k 200 k f − Frequency − Hz Figure 46. Figure 47. Figure 48. (VS = 3 V) TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY (VS = 5 V) TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY (VS = ±5 V) TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY 0.100 VO = 2 VPP VO = 2.8 VPP 0.010 VO = 1 VPP VS = 3 V, Bandwidth = 600 kHz, Gain = 2, RF = 2 kΩ, RL = 1 kΩ to VS/2 0.001 10 100 1k 10 k f − Frequency − Hz Figure 49. 200 k THD+N −Total Harmonic Distortion + Noise − % THD+N −Total Harmonic Distortion + Noise − % VS = 3.3 V, HD3 0.1000 VS = 5 V, Bandwidth = 600 kHz, Gain = 2, RF = 2 kΩ, RL = 1 kΩ to VS/2 VO = 4.8 VPP 0.0100 VO = 4.6 VPP 0.0010 VO = 4 VPP 0.0001 10 100 1k 10 k f − Frequency − Hz Figure 50. 200 k THD+N −Total Harmonic Distortion + Noise − % Harmonic Distortion − dBc −70 −60 VS = 3 V, HD2 THD+N −Total Harmonic Distortion + Noise − % Gain = 2, RL = 1 kΩ, to VS/2, f = 10 kHz Harmonic Distortion − dBc −60 (VS = 2.7 V) TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY (VS = 3.3 V, 15 V) HARMONIC DISTORTION vs OUTPUT VOLTAGE 0.1000 VS = ±5 V, Bandwidth = 600 kHz, Gain = 2, RF = 2 kΩ, RL = 1 kΩ 0.0010 VO = 9.6 VPP VO = 9 VPP 0.0100 VO = 4 VPP VO = 8 VPP 0.0001 10 100 1k 10 k 200 k f − Frequency − Hz Figure 51. 15 THS4281 www.ti.com SLOS432 – APRIL 2004 TYPICAL CHARACTERISTICS (continued) VS = 15 V, Bandwidth = 600 kHz, Gain = 2, RF = 2 kΩ, RL = 1 kΩ , to VS/2 0.0100 VO = 14.5 VPP VO = 14 VPP VO = 4 VPP VO = 8 VPP 0.0010 VO = 12 VPP 0.0001 10 100 1k 10 k 200 k 0.1000 VS = 3.3 V VS = 3 V VS = 2.7 V 0.0100 Amplifier Noise Limit Line 0.0010 f = 1 kHz, Bandwidth = 22 kHz, Gain = 2, RF = 2 kΩ, RL = 1 kΩ , to VS/2 0.1 1 10 VO − Output Voltage − VPP 20 0.1000 VS = 5 V VS = ±5 V VS = 15 V VS = 3.3 V VS = 3 V VS = 2.7 V 0.0100 0.0010 f = 10 kHz, Bandwidth = 80 kHz, Gain = 2, RF = 2 kΩ, RL = 1 kΩ , to VS/2 Amplifier Noise Limit Line 0.0001 0.1 1 10 Figure 53. Figure 54. (f = 100 kHz) TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT VOLTAGE (VS = 5 V) DIFFERENTIAL GAIN vs NUMBER OF LOADS (VS = 5 V) DIFFERENTIAL PHASE vs NUMBER OF LOADS 0.8 VS = ±5 V VS = 15 V VS = 3 V VS = 2.7 V 0.010 0.001 0.1 PAL ° 0.6 0.5 NTSC 0.4 0.3 Gain = 2 RF= 2.5 kΩ VS = 5 V 40 IRE − NTSC and Pal Worst Case ±100 IRE Ramp 0.2 0.1 Amplifier Noise Limit Line 1 10 VO − Output Voltage − VPP Figure 55. PAL 0.7 VS = 5 V VS = 3.3 V f = 100 kHz, Bandwidth = 600 kHz, Gain = 2, RF = 2 kΩ, RL = 1 kΩ , to VS/2 2 1.8 Differential Phase − 0.100 1 2 Number of Loads − 150 Ω Figure 56. 1.6 NTSC 1.4 1.2 1 0.8 0.6 Gain = 2 Rf = 2.5 kΩ VS = 5 V 40 IRE − NTSC and Pal Worst Case ±100 IRE Ramp 0.4 0.2 0 20 20 VO − Output Voltage − VPP Figure 52. Differential Gain − % THD+N −Total Harmonic Distortion + Noise − dBc VS = 15 V 0.0001 f − Frequency − Hz 16 VS = ±5 V VS = 5 V (f = 10 kHz) TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT VOLTAGE THD+N −Total Harmonic Distortion + Noise − dBc 0.1000 (f = 1 kHz) TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT VOLTAGE THD+N −Total Harmonic Distortion + Noise − dBc THD+N −Total Harmonic Distortion + Noise − dBc (VS = 15 V) TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY 3 0 1 2 Number of Loads − 150 Ω Figure 57. 3 THS4281 www.ti.com SLOS432 – APRIL 2004 TYPICAL CHARACTERISTICS (continued) (VS = ±5 V) DIFFERENTIAL PHASE vs NUMBER OF LOADS 1.4 PAL 0.8 NTSC 0.6 Gain = 2 RF= 2.5 kΩ VS = ±5 V 40 IRE − NTSC and Pal Worst Case ±100 IRE Ramp 0.4 0.2 1 1 NTSC 0.8 0.6 0.2 2 1 VS = 15 V 500 400 VS = ±5 V VS = 5 V 300 200 VS = 3 V 100 0 2 Number of Loads − 150 Ω −200 −40−30−20−10 0 10 20 30 40 50 60 70 80 90 3 TC − Case Temperature − °C Figure 59. Figure 60. (VS = 5 V) INPUT BIAS AND OFFSET CURRENT vs TEMPERATURE (VS = 15 V) INPUT BIAS AND OFFSET CURRENT vs TEMPERATURE SMALL-SIGNAL TRANSIENT RESPONSE 40 520 500 36 510 490 32 20 460 IIB+ 450 16 12 440 8 430 4 IOS 28 IIB− 490 24 480 20 470 16 IIB+ 460 12 450 8 440 4 Gain = 2 RL = 1 kΩ RF = 2.5 kΩ VS = ± 7.5 V −20 −30 −50 −60 0 100 200 300 400 500 600 700 Figure 63. LARGE-SIGNAL TRANSIENT RESPONSE (VS = 5 V) OVERDRIVE RECOVERY TIME (VS = ±5 V) OVERDRIVE RECOVERY TIME 0 −0.5 Gain = 2 RL = 1 kΩ RF = 2.5 kΩ VS = ± 5 V −2.5 4 3.75 3.25 2.75 2.25 Output 1 1.75 0 1.25 Input 4 3 2 1 2 1 0 0 −1 −2 −1 Output −3 −2 −4 −5 −1 100 200 300 400 500 600 700 800 Gain = 2 RL = 1 kΩ RF = 2.5 kΩ VS = ± 5 V 5 3 2 3 6 VO − Output Voltage − V Input VO − Output Voltage − V 1 4.25 Gain = 2 RL = 1 kΩ RF = 2.5 kΩ VS = 5 V 5 2 1.5 0 0 −10 t − Time − ns 6 −2 Input 10 Figure 62. Output −1.5 20 Figure 61. 3 −1 30 TC − Case Temperature − °C TC − Case Temperature − °C 0.5 40 −40 0 430 −40 −30−20 −10 0 10 20 30 40 50 60 70 80 90 0 420 −40 −30−20−10 0 10 20 30 40 50 60 70 80 90 2.5 VO − Output Voltage − mV 24 IIB− 470 500 Output 50 32 I OS − Input Offset Current − n A 28 I IB − Input Bias Current − n A IOS 480 60 36 VS =15 V I OS − Input Offset Current − n A VS = 5 V VO − Output Voltage − mV 600 Figure 58. 510 −3 VICR = VS/2 −100 0 3 Number of Loads − 150 Ω I IB − Input Bias Current − n A Gain = 2 Rf = 2.5 kΩ VS = ±5 V 40 IRE − NTSC and Pal Worst Case ±100 IRE Ramp 0.4 VI − Input Voltage − V 0 700 1.2 Differential Phase − Differential Gain − % 1 800 1.4 PAL ° 1.2 1.6 VOS− Input Offset Voltage − µ V 1.6 INPUT OFFSET VOLTAGE vs TEMPERATURE 0 0.5 1 1.5 2 2.5 t − Time − µs 3 3.5 0.75 −6 VI − Input Voltage − V (VS = ±5 V) DIFFERENTIAL GAIN vs NUMBER OF LOADS Input 0 0.5 1 1.5 2 2.5 3 −3 3.5 t − Time − µs t − Time − ns Figure 64. Figure 65. Figure 66. 17 THS4281 www.ti.com SLOS432 – APRIL 2004 TYPICAL CHARACTERISTICS (continued) OVERDRIVE RESPONSE OUTPUT VOLTAGE vs TIME 2 V O − Output Voltage − V 6 VS = ±2.5 V Gain = 2, RL = 1 kΩ, RF = 2 kΩ VO 4 1 2 0 VI 0 −1 −2 −2 −4 −3 0 20 40 60 t − Time − s Figure 67. 18 80 −6 100 V I − Input Voltage − V 3 THS4281 www.ti.com SLOS432 – APRIL 2004 APPLICATION INFORMATION +VS HIGH-SPEED OPERATIONAL AMPLIFIERS The THS4281 is a unity gain stable rail-to-rail input and output voltage feedback operational amplifier designed to operate from a single 2.7-V to 16.5-V power supply. + VI VO _ Rf 2.49 kΩ To Load 2.49 kΩ Rg 0.1 µF 6.8 µF + and Figure 68 shows the noninverting gain configuration of 2 V/V used to demonstrate the typical performance curves. Voltage feedback amplifiers can use a wide range of resistors values to set their gain with minimal impact on frequency response. Larger-valued resistors decrease loading of the feedback network on the output of the amplifier, but may cause peaking and instability. For a gain of +2, feedback resistor values between 1 kΩ and 4 kΩ are recommended for most applications. However, as the gain increases, the use of even higher feedback resistors can be used to conserve power. This is due to the inherent nature of amplifiers becoming more stable as the gain increases, at the expense of bandwidth. Figure 69 and Figure 70 show the THS4281 using feedback resistors of 10 kΩ and 100 kΩ. Be cautioned that using such high values with high-speed amplifiers is not typically recommended, but under certain conditions, such as high gain and good high-speed-PCB layout practices, such resistances can be used. Figure 68. Wideband, Noninverting Gain Configuration 24 RF = 100 kΩ 20 Signal Gain − dB WIDEBAND, NONINVERTING OPERATION −VS RF = 1.65 kΩ and 10 kΩ 16 12 8 VS = 3 V Gain = 10, RL = 1 kΩ, VO = 0.1 VPP 4 0 0.1 1 10 100 f − Frequency − MHz Figure 69. Signal Gain vs Frequency, VS = 3 V 24 RF = 100 kΩ 20 Signal Gain − dB • • • • • • Wideband, Noninverting Operation Wideband, Inverting Gain Operation Video Drive Circuits Single-Supply Operation Power Supply Decoupling Techniques Recommendations Active Filtering With the THS4281 Driving Capacitive Loads Board Layout Thermal Analysis Additional Reference Material Mechanical Package Drawings 0.1 µF 6.8 µF 50-Ω Source 49.9 Ω Applications Section Contents • • • • • + 16 RF = 2.5 kΩ and 10 kΩ 12 8 4 0 0.1 VS = ±5 V Gain = 10, RL = 1 kΩ, VO = 0.1 VPP 1 10 100 f − Frequency − MHz Figure 70. Signal Gain vs Frequency, VS = ±5 V 19 THS4281 www.ti.com SLOS432 – APRIL 2004 WIDEBAND, INVERTING OPERATION Figure 71 shows a typical inverting configuration where the input and output impedances and noise gain from Figure 68 are retained with an inverting circuit gain of -1 V/V. +VS + 0.1 µF 6.8 µF + RT 1.24 kΩ CT 0.1 µF VO _ To Load 50-Ω Source Rg VI Rf 2.49 kΩ RM 51.1 Ω 2.49 kΩ 0.1 µF 6.8 µF + −VS Figure 71. Wideband, Inverting Gain Configuration In the inverting configuration, some key design considerations must be noted. One is that the gain resistor (Rg) becomes part of the signal channel input impedance. If the input impedance matching is desired (which is beneficial whenever the signal is coupled through a cable, twisted pair, long PC board trace, or other transmission line conductors), Rg may be set equal to the required termination value and Rf adjusted to give the desired gain. However, care must be taken when dealing with low inverting gains, as the resultant feedback resistor value can present a significant load to the amplifier output. For example, an inverting gain of 2, setting Rg to 49.9 Ω for input matching, eliminates the need for RM but requires a 100-Ω feedback resistor. The 100-Ω feedback resistor, in parallel with the external load, causes excessive loading on the amplifier output. To eliminate this excessive loading, it is preferable to increase both Rg and Rf values, as shown in Figure 71, and then achieve the input matching impedance with a third resistor (RM) to ground. The total input impedance is the parallel combination of Rg and RM. 20 Another consideration in inverting amplifier design is setting the bias current cancellation resistor (RT) on the noninverting input. If the resistance is set equal to the total dc resistance presented to the device at the inverting terminal, the output dc error (due to the input bias currents) is reduced to the input offset current multiplied by RT. In Figure 71, the dc source impedance presented at the inverting terminal is 2.49 kΩ || (2.49 kΩ + 25.3 Ω) ≅ 1.24 kΩ. To reduce the additional high-frequency noise introduced by the resistor at the noninverting input, RT is bypassed with a 0.1-µF capacitor to ground (CT). SINGLE-SUPPLY OPERATION The THS4281 is designed to operate from a single 2.7-V to 16.5-V power supply. When operating from a single power supply, care must be taken to ensure the input signal and amplifier are biased appropriately to allow for the maximum output voltage swing and not violate VICR. The circuits shown in Figure 72 shows inverting and noninverting amplifiers configured for single-supply operation. +VS 50-Ω Source + VI 49.9 Ω RT VO _ To Load +VS Rf 2 Rg 2 kΩ 2 kΩ Power Supply Bypassing Not Shown For Simplicity +VS 2 Rf VS 2 kΩ 50-Ω Source Rg VI RT 51.1 Ω _ 2 kΩ RT + VO To Load +VS +VS 2 2 CT Figure 72. DC-Coupled Single Supply Operation THS4281 www.ti.com SLOS432 – APRIL 2004 APPLICATION CIRCUITS Active Filtering With the THS4281 2.05 k The two most common low-pass filter circuits used are the Sallen-Key filter and the Multiple Feedback (MFB)–aka Rauch filter. FilterPro was used to determine a 2-pole Butterworth response filter with a corner (-3 dB) frequency of 100 kHz which is shown in Figure 73 and Figure 74. One of the advantages of the MFB filter, a much better high frequency rejection, is clearly shown in the response shown in Figure 75. This is due to the inherent R-C filter to ground being the first elements in the design of the MFB filter. The Sallen-Key design also has an R-C filter, but the capacitor connects directly to the output. At very high frequencies, where the amplifier's access loop gain is decreasing, the ability of the amplifier to reject high frequencies is severely reduced and allows the high frequency signals to pass through the system. One other advantage of the MFB filter is the reduced sensitivity in component variation. This is important when using real-world components where capacitors can easily have ±10% variations. 2 k 2 k 5V _ VI 649 2.61 k 1.5 nF 1 nF VO + −5V RL 1 k Figure 73. Second-Order Sallen-Key 100-kHz Butterworth Filter, Gain = 2 V/V 270 pF 1.02 k 5V 2.1 k _ VI VO + 2.2 nF RL 1 k −5V Figure 74. Second-Order MFB 100-kHz Butterworth Filter, Gain = 2 V/V 10 Sallen-Key Response 0 −10 Signal Gain − dB High performance active filtering with the THS4281 is achievable due to the amplifier's good slew rate, wide bandwidth, and voltage feedback architecture. Several options are available for high-pass, low-pass, bandpass, and bandstop filters of varying orders. Filters can be quite complex and time consuming to design. Several books and application reports are available to help design active filters. But, to help simplify the process and minimize the chance of miscalculations, Texas Instruments has developed a filter design program called FilterPro™. FilterPro is available for download at no cost from TI's Web site (www.ti.com). −20 −30 −40 −50 MFB Response −60 VS = 3 V, 5 V, ±5 V, 15 V, VO = 100 mVPP −70 −80 1k 10k 100k 1M 10M 100M f − Frequency − Hz Figure 75. Second-Order 100-kHz Active Filter Response Driving Capacitive Loads One of the most demanding, and yet common, load conditions for an op amp is capacitive loading. Often, the capacitive load is the input of an A/D converter, including additional external capacitance, which may be recommended to improve A/D linearity. A high-speed, high open-loop gain amplifier like the THS4281 can be susceptible to instability and peaking when a capacitive load is placed directly on the output. When the amplifier's open-loop output resistance is considered, this capacitive load introduces an additional pole in the feedback path that decreases the phase margin. When the primary considerations are frequency response flatness, pulse response fidelity, or distortion, a simple and effective solution is to isolate the capacitive load from the feedback loop by inserting a small series isolation resistor (10 Ω to 25 Ω) between the amplifier output and the capacitive load. 21 THS4281 www.ti.com SLOS432 – APRIL 2004 Power Supply Decoupling Techniques and Recommendations Power supply decoupling is a critical aspect of any high-performance amplifier design. Careful decoupling provides higher quality ac performance. The following guidelines ensure the highest level of performance. 1. Place decoupling capacitors as close to the power supply inputs as possible, with the goal of minimizing the inductance. 2. Placement priority should put the smallest valued capacitors closest to the device. 3. Use of solid power and ground planes is recommended to reduce the inductance along power supply return current paths (with the exception of the areas underneath the input and output pins as noted below). 4. A bulk decoupling capacitor is recommended (6.8 to 22 µF) within 1 inch, and a ceramic (0.1 µF) within 0.1 inch of the power input pins. NOTE: The bulk capacitor may be shared by other op amps. BOARD LAYOUT Achieving optimum performance with a high frequency amplifier like the THS4281 requires careful attention to board layout parasitics and external component types. See the EVM layout figures in the Design Tools Section. Recommendations that optimize performance include: 1. Minimize parasitic capacitance to any ac ground for all of the signal I/O pins. Parasitic capacitance on the output and inverting input pins can cause instability and on the noninverting input, it can react with the source impedance to cause unintentional band limiting. To reduce unwanted capacitance, a window around the signal I/O pins should be opened in all of the ground and power planes around those pins. Otherwise, ground and power planes should be unbroken elsewhere on the board. 2. Minimize the distance (< 0.1 inch) from the power supply pins to high frequency 0.1-µF decoupling capacitors. Avoid narrow power and ground traces to minimize inductance. The power supply connections should always be decoupled as described above. 3. Careful selection and placement of external components preserves the high frequency performance of the THS4281. Resistors should be a low reactance type. Surface-mount resistors work best and allow a tighter overall layout. 22 Metal-film, axial-lead resistors can also provide good high frequency performance. Again, keep their leads and PC board trace length as short as possible. Never use wire wound type resistors in a high frequency application. Because the output pin and inverting input pin are the most sensitive to parasitic capacitance, always position the feedback and series output resistor, if any, as close as possible to the output pin. Other network components, such as noninverting input termination resistors, should also be placed close to the package. Excessively high resistor values can create significant phase lag that can degrade performance. Keep resistor values as low as possible, consistent with load-driving considerations. It is suggested that a good starting point for design is to set the Rf to 2 kΩ for low-gain, noninverting applications. Doing this automatically keeps the resistor noise terms reasonable and minimizes the effect of parasitic capacitance. 4. Connections to other wideband devices on the board should be made with short direct traces or through onboard transmission lines. For short connections, consider the trace and the input to the next device as a lumped capacitive load. Relatively wide traces (50 mils to 100 mils) should be used, preferably with ground and power planes opened up around them. Estimate the total capacitive load and set RISO from the plot of recommended RISO vs capacitive load. Low parasitic capacitive loads (<4 pF) may not need an R(ISO), because the THS4281 is nominally compensated to operate at unity gain (+1 V/V) with a 2-pF capacitive load. Higher capacitive loads without an R(ISO) are allowed as the signal gain increases. If a long trace is required, and the 6-dB signal loss intrinsic to a doubly terminated transmission line is acceptable, implement a matched impedance transmission line using microstrip or stripline techniques (consult an ECL design handbook for microstrip and stripline layout techniques). A matching series resistor into the trace from the output of the THS4281 is used as well as a terminating shunt resistor at the input of the destination device. Remember also that the terminating impedance is the parallel combination of the shunt resistor and the input impedance of the destination device: this total effective impedance should be set to match the trace impedance. If the 6-dB attenuation of a doubly terminated transmission line is unacceptable, a long trace can be series-terminated at the source end only. Treat the trace as a capacitive load in this case, and set the series resistor value as shown in the plot of R(ISO) vs capacitive load. If the input impedance of the destination device is low, there is signal attenuation due to the voltage divider formed by R(ISO) into the terminating impedance. THS4281 www.ti.com SLOS432 – APRIL 2004 A 50-Ω environment is normally not necessary onboard, and in fact a higher impedance environment improves distortion as shown in the distortion versus load plots. 5. Socketing a high speed part like the THS4281 is not recommended. The additional lead length and pin-to-pin capacitance introduced by the socket can create a troublesome parasitic network which can make it almost impossible to achieve a smooth, stable frequency response. Best results are obtained by soldering the THS4281 onto the board. When determining whether or not the device satisfies the maximum power dissipation requirement, it is important to consider not only quiescent power dissipation, but also dynamic power dissipation. Often maximum power dissipation is difficult to quantify because the signal pattern is inconsistent, but an estimate of the RMS value can provide a reasonable analysis. THERMAL ANALYSIS Texas Instruments is committed to providing its customers with the highest quality of applications support. To support this goal, an evaluation board has been developed for the THS4281 operational amplifier. The evaluation board is available and easy to use allowing for straight-forward evaluation of the device. These evaluation board can be obtained by ordering through the Texas Instruments Web site, www.ti.com, or through your local Texas Instruments Sales Representative. A schematic for the evaluation board is shown in Figure 77 with their default component values. Unpopulated footprints are shown to provide insight into design flexibility. The THS4281 does not incorporate automatic thermal shutoff protection, so the designer must take care to ensure that the design does not violate the absolute maximum junction temperature of the device. Failure may result if the absolute maximum junction temperature of 150° C is exceeded. For long-term dependability, the junction temperature should not exceed 125°C. The thermal characteristics of the device are dictated by the package and the PC board. Maximum power dissipation for a given package can be calculated using the following formula. Tmax–T A P Dmax JA where: PDmax is the maximum power dissipation in the amplifier (W). Tmax is the absolute maximum junction temperature (°C). TA is the ambient temperature (°C). θJA = θJC + θCA θJC is the thermal coefficient from the silicon junctions to the case (°C/W). θCA is the thermal coefficient from the case to ambient air (°C/W). P D − Maximum Power Dissipation − W 1.8 1.6 8-pin SOIC (D) Package 1.4 8-pin MSOP (DGK) Package 1.2 1 0.8 DESIGN TOOLS Evaluation Fixtures Information and Application Support Computer simulation of circuit performance using SPICE is often useful when analyzing the performance of analog circuits and systems. This is particularly true for video and RF amplifier circuits where parasitic capacitance and inductance can have a major effect on circuit performance. A SPICE model for the THS4281 device is available through either the Texas Instruments Web site (www.ti.com) or as one model on a disk from the Texas Instruments Product Information Center (1–800–548–6132). The PIC is also available for design assistance and detailed product information at this number. These models do a good job of predicting small-signal ac and transient performance under a wide variety of operating conditions. They are not intended to model the distortion characteristics of the amplifier, nor do they attempt to distinguish between the package types in their small-signal ac performance. Detailed information about what is and is not modeled is contained in the model file itself. 0.6 0.4 0.2 0 −40 5-pin SOT23 (DBV) Package −20 0 20 40 60 80 TA − Free-Air Temperature − °C 100 θJA = 97.5°C/W for 8-Pin SOIC (D) θJA = 180.8°C/W for 8-Pin MSOP (DGK) θJA = 255.4°C/W for 5-Pin SOT−23 (DBV) TJ = 125°C, No Airflow Figure 76. Maximum Power Dissipation vs Ambient Temperature 23 THS4281 www.ti.com J7 J5 –vs C4 22 µF R4 2 kΩ R0603_1% + R2 2 kΩ R0603_1% J1 +vs FB2 FB1 C3 0.1 µF C0805 C2 100 pF +Vs –Vs SLOS432 – APRIL 2004 +vs U1 4 SIDEMOUNT_SMA R1 51.1 Ω R0805_1% 6 3 2 1 + C5 22 µF R5 953 Ω R0603_1% SIDEMOUNT_SMA THS4281DBV R6 R0603_1% C1 C1206 TP1 J6 R3 49.9 Ω R0805_1% J4 GND J3 PD SIDEMOUNT_SMA C7 100 pF 5 –vs J2 C6 0.1 µF C0805 Figure 77. THS4281EVM Schematic TOP Figure 78. THS4281EVM Layout (Top Layer and Silkscreen Layer) 24 Layer 2 − GND Figure 79. THS4281EVM Board Layout THS4281 www.ti.com SLOS432 – APRIL 2004 Layer 3 − GND Figure 80. THS4281EVM Board Layout BOTTOM Figure 81. THS4281EVM Board Layout 25 THS4281 www.ti.com SLOS432 – APRIL 2004 BILL OF MATERIALS THS4281DBV EVM ITEM (1) DESCRIPTION SMD SIZE REFERENCE DESIGNATOR PCB QTY. FB1, FB2 2 1 Bead, Ferrite, 3A, 80 Ω 1206 2 OPEN 1206 C1 1 3 Cap, 22 µF, tanatalum, 25 V, 10% D C4, C5 4 Cap, 0.1 µF, ceramic, X7R, 50V 0805 5 Cap, 100 pF, ceramic, 5%, 150V AQ12 6 OPEN 7 MANUFACTURER'S PART NUMBER (1) DISTRIBUTOR'S PART NUMBER (STEWARD) HI1206N800R-00 (DIGI-KEY) 240-1010-1-ND 2 (AVX) TAJD226K025R (GARRETT) TAJD226K025R C3, C6 2 (AVX) 08055C104KAT2A (GARRETT) 08055C104KAT2A C2, C7 2 (AVX) AQ12EM101JAJME (TTI) AQ12EM101JAJME 0603 R6 1 Resistor, 2 KΩ, 1/10W, 1% 0603 R2, R4 2 (PHYCOMP) 9C06031A2001FKHFT (GARRETT) 9C06031A2001FKHFT 8 Resistor, 953 Ω, 1/10W, 1% 0603 R5 1 (PHYCOMP) 9C06031A9530FKRFT (GARRETT) 9C06031A9530FKRFT 9 Resistor, 51.1 Ω, 1/8W, 1% 0805 R1 1 (PHYCOMP) 9C08052A51R1FKHFT (GARRETT) 9C08052A51R1FKHFT 10 Resistor, 49.9 Ω, 1/8W, 1% 0805 R3 1 (PHYCOMP) 9C08052A49R9FKHFT (GARRETT) 9C08052A49R9FKHFT 11 Jack, banana receptance, 0.25" diameter hole J5, J6, J7 3 (HH SMITH) 101 (NEWARK) 35F865 12 OPEN J3 1 13 Test point, black TP1 1 (KEYSTONE) 5001 (DIGI-KEY) 5001K-ND 14 Connector, edge, SMA PCB JACK J1, J2, J4 3 (JOHNSON) 142-0701-801 (NEWARK) 90F2624 15 Standoff, 4-40 HEX, 0.625" length 4 (KEYSTONE) 1804 (NEWARK) 89F1934 16 Screw, PHILLIPS, 4-40, 0.250" 4 SHR-0440-016-SN 17 IC, THS4281 1 (TI) THS4281DBV 18 Board, printed circuit 1 (TI) EDGE # 6448015 Rev.A U1 The manufacturer's part numbers are used for test purposes only. ADDITIONAL REFERENCE MATERIALS • • • • 26 PowerPAD Made Easy, application brief, (SLMA004) PowerPAD Thermally Enhanced Package, technical brief (SLMA002) Active Low-Pass Filter Design, application report (SLOA049) FilterPro MFB and Sallen-Key Low-Pass Filter Design Program, application report (SBFA001) PACKAGE OPTION ADDENDUM www.ti.com 19-May-2005 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty THS4281D ACTIVE SOIC D 8 THS4281DBVR ACTIVE SOT-23 DBV THS4281DBVRG4 ACTIVE SOT-23 THS4281DBVT ACTIVE THS4281DBVTG4 75 Lead/Ball Finish MSL Peak Temp (3) Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM 5 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM DBV 5 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM SOT-23 DBV 5 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM ACTIVE SOT-23 DBV 5 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM THS4281DGK ACTIVE MSOP DGK 8 100 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM THS4281DGKR ACTIVE MSOP DGK 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM THS4281DGKRG4 ACTIVE MSOP DGK 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM THS4281DR ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM THS4281DRG4 ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM (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) 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. 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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