AD713

a FEATURES Enhanced Replacement for LF347 and TL084 AC PERFORMANCE 1 ms Settling to 0.01% for 10 V Step 20 V/ms Slew Rate 0.0003% Total Harmonic Distortion (THD) 4 MHz Unity Gain Bandwidth DC PERFORMANCE 0.5 mV max Offset Voltage (AD713K) 20 mV/°C max Drift (AD713K) 200 V/mV min Open Loop Gain (AD713K) 2 mV p-p typ Noise, 0.1 Hz to 10 Hz True 14-Bit Accuracy Single Version: AD711, Dual Version: AD712 Available in 16-Pin SOIC, 14-Pin Plastic DIP and Hermetic Cerdip Packages Standard Military Drawing Available APPLICATIONS Active Filters Quad Output Buffers for 12- and 14-Bit DACs Input Buffers for Precision ADCs Photo Diode Preamplifier Application Quad Precision, Low Cost, High Speed, BiFET Op Amp AD713 CONNECTION DIAGRAMS Plastic (N) and Cerdip (Q) Packages SOIC (R) Package OUTPUT OUTPUT –IN +IN +VS +IN –IN OUTPUT 1 2 3 4 5 6 7 2 3 1 4 14 OUTPUT 13 –IN 12 +IN –IN +IN +VS +IN –IN OUTPUT NC 1 2 3 4 5 6 7 8 2 3 1 4 16 15 14 OUTPUT –IN +IN –VS +IN –IN OUTPUT NC AD713 (TOP VIEW) 13 12 11 10 9 AD713 (TOP VIEW) 11 –VS 10 +IN 9 8 –IN OUTPUT NC = NO CONNECT The AD713 is offered in a 16-pin SOIC, 14-pin plastic DIP and hermetic cerdip package. PRODUCT HIGHLIGHTS PRODUCT DESCRIPTION The AD713 is a quad operational amplifier, consisting of four AD711 BiFET op amps. These precision monolithic op amps offer excellent dc characteristics plus rapid settling times, high slew rates, and ample bandwidths. In addition, the AD713 provides the close matching ac and dc characteristics inherent to amplifiers sharing the same monolithic die. The single-pole response of the AD713 provides fast settling: l µs to 0.01%. This feature, combined with its high dc precision, makes the AD713 suitable for use as a buffer amplifier for 12or 14-bit DACs and ADCs. It is also an excellent choice for use in active filters in 12-, 14- and 16-bit data acquisition systems. Furthermore, the AD713’s low total harmonic distortion (THD) level of 0.0003% and very close matching ac characteristics make it an ideal amplifier for many demanding audio applications. The AD713 is internally compensated for stable operation at unity gain and is available in seven performance grades. The AD713J and AD713K are rated over the commercial temperature range of 0°C to 70°C. The AD713A and AD713B are rated over the industrial temperature of –40° C to +85 ° C. The AD713S and AD713T are rated over the military temperature range of –55°C to +125°C and are available processed to standard microcircuit drawings. R EV. C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. 1. The AD713 is a high speed BiFET op amp that offers excellent performance at competitive prices. It upgrades the performance of circuits using op amps such as the TL074, TL084, LT1058, LF347 and OPA404. 2. Slew rate is 100% tested for a guaranteed minimum of 16 V/µs (J, A and S Grades). 3. The combination of Analog Devices’ advanced processing technology, laser wafer drift trimming and well-matched ion-implanted JFETs provides outstanding dc precision. Input offset voltage, input bias current and input offset current are specified in the warmed-up condition and are 100% tested. 4. Very close matching of ac characteristics between the four amplifiers makes the AD713 ideal for high quality active filter applications. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 www.analog.com Fax: 781/326-8703 © Analog Devices, Inc., 2002 AD713–SPECIFICATIONS (V = S 15 V @ TA = 25 C unless otherwise noted) AD713J/A/S Typ 0.3 0.5 5 95 95 15 40 55 10 Max 1.5 2/2/2 84 84 150 3.4/9.6/154 200 75 1.7/4.8/77 1.8 2.3/2.3/2.3 100 –130 –95 3.4 18 1.2 Min AD713K/B/T Typ Max 0.2 0.4 5 100 100 15 40 55 10 Unit Parameter INPUT OFFSET VOLTAGE Initial Offset Offset vs. Temp vs. Supply Long-Term Stability INPUT BIAS CURRENT2 1 Conditions Min TMIN to TMAX 78 76/76/76 TMIN to TMAX VCM = 0 V VCM = 0 V @ TMAX VCM = ± 10 V VCM = 0 V VCM = 0 V @ TMAX 0.5 mV 0.7/0.7/1.0 mV 20/20/15 µV/°C dB dB µV/Month 75 1.7/4.8/77 120 35 0.8/2.2/36 0.8 1.0/1.0/1.3 25 35 –130 –95 pA nA pA pA nA mV mV µV/°C pA dB dB MHz kHz V/µs µs % INPUT OFFSET CURRENT MATCHING CHARACTERISTICS Input Offset Voltage TMIN to TMAX Input Offset Voltage Drift Input Bias Current Crosstalk FREQUENCY RESPONSE Small Signal Bandwidth Full Power Response Slew Rate Settling Time to 0.01% Total Harmonic Distortion INPUT IMPEDANCE Differential Common Mode INPUT VOLTAGE RANGE Differential3 Common-Mode Voltage4 Common Mode Rejection Ratio TMIN to TMAX VCM = ± 10 V TMIN to TMAX VCM = ± 11 V TMIN to TMAX 0.1 Hz to 10 Hz f = 10 Hz f = 100 Hz f = 1 kHz f = 10 kHz f = 1 kHz VO = ± 10 V; RL ≥ 2 kΩ TMIN to TMAX RL ≥ 2 k Ω TMIN to TMAX Short Circuit 150 100/100/100 –11 78 76/76/76 72 70/70/70 0.5 0.7 8 10 0.4 0.6 6 10 f = 1 kHz f = 100 kHz Unity Gain VO = 20 V p-p Unity Gain f = 1 kHz; RL ≥ 2 kΩ; VO = 3 V rms 3.0 16 4.0 200 20 1.0 0.0003 4.0 200 20 1.0 0.0003 1.2 3×1012 5.5 3×1012 5.5 ± 20 +14.5, –11.5 +13 88 84 84 80 2 45 22 18 16 0.01 400 200 100 –11 84 82 78 74 3×1012 5.5 3×1012 5.5 ± 20 +14.5, –11.5 +13 94 90 90 84 2 45 22 18 16 0.01 400 Ω pF Ω pF V V V dB dB dB dB µV p-p nV/√Hz nV/√Hz nV/√Hz nV/√Hz pA/√Hz V/mV V/mV V V mA V V mA INPUT VOLTAGE NOISE INPUT CURRENT NOISE OPEN-LOOP GAIN OUTPUT CHARACTERISTICS Voltage Current POWER SUPPLY Rated Performance Operating Range Quiescent Current TRANSISTOR COUNT +13, –12.5 +13.9, –13.3 ± 12/± 12/ 12 +13.8, –13.1 25 ± 15 4.5 10.0 18 13.5 +13, –12.5 +13.9, –13.3 12 +13.8, –13.1 25 ± 15 4.5 10.0 120 18 12.0 # of Transistors 120 NOTES 1 Input Offset Voltage specifications are guaranteed after 5 minutes of operation at T A = 25°C. 2 Bias Current specifications are guaranteed maximum at either input after 5 minutes of operation at T A = 25°C. For higher temperatures, the current doubles every 10 °C. 3 Defined as voltage between inputs, such that neither exceeds ± 10 V from ground. 4 Typically exceeding –14.1 V negative common-mode voltage on either input results in an output phase reversal. Specifications subject to change without notice. –2– REV. C AD713 ABSOLUTE MAXIMUM RATINGS 1, 2 Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 18 V Internal Power Dissipation2 Input Voltage3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 18 V Output Short-Circuit Duration (For One Amplifier) . . . . . . . . . . . . . . . . . . . . . . . . Indefinite Differential Input Voltage . . . . . . . . . . . . . . . . . . +VS and –VS Storage Temperature Range (Q) . . . . . . . . . . –65°C to +150°C Storage Temperature Range (N, R) . . . . . . . . –65°C to +125°C Operating Temperature Range AD713J/K . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C AD713A/B . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C AD713S/T . . . . . . . . . . . . . . . . . . . . . . . . . –55°C to +125°C Lead Temperature Range (Soldering 60 sec) . . . . . . . . . . 300°C NOTES 1 Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 2 Thermal Characteristics: 14-Pin Plastic Package: θJC = 30°C/Watt; θJA = 100°C/Watt 14-Pin Cerdip Package: θJC = 30°C/Watt; θJA = 110°C/Watt 16-Pin SOIC Package: θJC = 30°C/ Watt; θJA = 100°C/Watt 3 For supply voltages less than ± 18 V, the absolute maximum input voltage is equal to the supply voltage. ORDERING GUIDE Model AD713AQ AD713BQ AD713JN AD713JR-16 AD713JR-16-REEL AD713JR-16-REEL7 AD713KN AD713SQ2 AD713TQ2 5962-9063301MCA 5962-9063302MCA2 1 2 Temperature Range –40°C to +85°C –40°C to +85°C 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C –55°C to +125°C –55°C to +125°C –55°C to +125°C –55°C to +125°C Package Description 14-Pin Ceramic DIP 14-Pin Ceramic DIP 14-Pin Plastic DIP 16-Pin Plastic SOIC 16-Pin Plastic SOIC 16-Pin Plastic SOIC 14-Pin Plastic DIP 14-Pin Ceramic DIP 14-Pin Ceramic DIP 14-Pin Ceramic DIP 14-Pin Ceramic DIP Package Option1 Q-14 Q-14 N-14 R-16 R-16 R-16 N-14 Q-14 Q-14 Q-14 Q-14 N = Plastic DIP; Q = Cerdip; R = Small Outline IC (SOIC). Not for new designs. Obsolete April 2002. CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the AD713 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. WARNING! ESD SENSITIVE DEVICE REV. C –3– AD713 –Typical Performance Characteristics TPC 1. Input Voltage Swing vs. Supply Voltage TPC 2. Output Voltage Swing vs. Supply Voltage TPC 3. Output Voltage Swing vs. Load Resistance TPC 4. Quiescent Current vs. Supply Voltage TPC 5. Input Bias Current vs. Temperature TPC 6. Output Impedance vs. Frequency, G = 1 TPC 7. Input Bias Current vs. Common Mode Voltage TPC 8. Short-Circuit Current Limit vs. Temperature TPC 9. Gain Bandwidth Product vs. Temperature –4– REV. C Typical Performance Characteristics– AD713 TPC 10. Open-Loop Gain and Phase Margin vs. Frequency TPC 11. Open-Loop Gain vs. Supply Voltage TPC 12. Power Supply Rejection vs. Frequency TPC 13. Common Mode Rejection vs. Frequency TPC 14. Large Signal Frequency Response TPC 15. Output Swing and Error vs. Settling Time TPC 16. Total Harmonic Distortion vs. Frequency TPC 17. Input Noise Voltage Spectral Density TPC 18. Slew Rate vs. Input Error Signal REV. C –5– AD713 TPC 19. Crosstalk Test Circuit TPC 20. Crosstalk vs. Frequency TPC 21a. Unity Gain Follower TPC 21b. Unity Gain Follower Pulse Response (Large Signal) TPC 22b. Unity Gain Inverter Pulse Response (Large Signal) TPC 22a. Unity Gain Inverter TPC 21c. Unity Gain Follower Pulse Response (Small Signal) TPC 22c. Unity Gain Inverter Pulse Response (Small Signal) –6– REV. C AD713 MEASURING AD713 SETTLING TIME The photos of Figures 2 and 3 show the dynamic response of the AD713 while operating in the settling time test circuit of Figure 1. The input of the settling time fixture is driven by a flat-top pulse generator. The error signal output from the false summing node of A1, the AD713 under test, is clamped, amplified by op amp A2 and then clamped again. The error signal is thus clamped twice: once to prevent overloading amplifier A2 and then a second time to avoid overloading the oscilloscope preamp. A Tektronix oscilloscope preamp type 7A26 was carefully chosen because it recovers from the approximately 0.4 V overload quickly enough to allow accurate measurement of the AD713’s 1 µs settling time. Amplifier A2 is a very high speed FET input op amp; it provides a voltage gain of 10, amplifying the error signal output of the AD713 under test (providing an overall gain of 5). Figure 3. Settling Characteristics to –10 V Step. Upper Trace: Output of AD713 Under Test (5 V/div). Lower Trace: Amplified Error Voltage (0.01%/ div) POWER SUPPLY BYPASSING Figure 1. Settling Time Test Circuit The power supply connections to the AD713 must maintain a low impedance to ground over a bandwidth of 4 MHz or more. This is especially important when driving a significant resistive or capacitive load, since all current delivered to the load comes from the power supplies. Multiple high quality bypass capacitors are recommended for each power supply line in any critical application. A 0.1 µF ceramic and a 1 µF electrolytic capacitor as shown in Figure 4 placed as close as possible to the amplifier (with short lead lengths to power supply common) will assure adequate high frequency bypassing in most applications. A minimum bypass capacitance of 0.1 µF should be used for any application. Figure 2. Settling Characteristics 0 V to +10 V Step. Upper Trace: Output of AD713 Under Test (5 V/div). Lower Trace: Amplified Error Voltage (0.01%/div) Figure 4. Recommended Power Supply Bypassing REV. C –7– AD713 A HIGH SPEED INSTRUMENTATION AMPLIFIER CIRCUIT A HIGH SPEED FOUR OP AMP CASCADED AMPLIFIER CIRCUIT The instrumentation amplifier circuit shown in Figure 5 can provide a range of gains from unity up to 1000 and higher using only a single AD713. The circuit bandwidth is 1.2 MHz at a gain of 1 and 250 kHz at a gain of 10; settling time for the entire circuit is less than 5 µs to within 0.01% for a 10 V step, (G = 10). Other uses for amplifier A4 include an active data guard and an active sense input. Figure 7 shows how the four amplifiers of the AD713 may be connected in cascade to form a high gain, high bandwidth amplifier. This gain of 100 amplifier has a –3 dB bandwidth greater than 600 kHz. Figure 7. A High Speed Four Op Amp Cascaded Amplifier Circuit Figure 5. A High Speed Instrumentation Amplifier Circuit Table I provides a performance summary for this circuit. The photo of Figure 6 shows the pulse response of this circuit for a gain of 10. Table I. Performance Summary for the High Speed Instrumentation Amplifier Circuit Gain 1 2 10 RG NC 20 kΩ 4.04 kΩ Bandwidth 1.2 MHz 1.0 MHz 0.25 MHz T Settle (0.01%) 2 µs 2 µs 5 µs Figure 8. THD Test Circuit HIGH SPEED OP AMP APPLICATIONS AND TECHNIQUES DAC Buffers (I-to-V Converters) Figure 6. The Pulse Response of the High Speed Instrumentation Amplifier. Gain = 10 The wide input dynamic range of JFET amplifiers makes them ideal for use in both waveform reconstruction and digital-audio DAC applications. The AD713, in conjunction with the AD1860 DAC, can achieve 0.0016% THD (here at a 4fs or a 176.4 kHz update rate) without requiring the use of a deglitcher. Just such a circuit is shown in Figure 9. The 470 pF feedback capacitor used with IC2a, along with op amp IC2b and its associated components, together form a 3-pole low-pass filter. Each or all of these poles can be tailored for the desired attenuation and phase characteristics required for a particular application. In this application, one half of an AD713 serves each channel in a twochannel stereo system. –8– REV. C AD713 Figure 9. A D/A Converter Circuit for Digital Audio Figure 11. The AD713 as an ADC Buffer Figure 10. Harmonic Distortion as Frequency for the Digital Audio Circuit of Figure 9 Driving the Analog Input of an A/D Converter An op amp driving the analog input of an A/D converter, such as that shown in Figure 11, must be capable of maintaining a constant output voltage under dynamically changing load conditions. In successive approximation converters, the input current is compared to a series of switched trial currents. The comparison point is diode clamped but may vary by several hundred millivolts, resulting in high frequency modulation of the A/D input current. The output impedance of a feedback amplifier is made artificially low by its loop gain. At high frequencies, where the loop gain is low, the amplifier output impedance can approach its open loop value. Most IC amplifiers exhibit a minimum open loop output impedance of 25 Ω, due to current limiting resistors. A few hundred microamps reflected from the change in converter loading can introduce errors in instantaneous input voltage. If the A/D conversion speed is not excessive and the bandwidth of the amplifier is sufficient, the amplifier’s output will return to the nominal value before the converter makes its comparison. However, many amplifiers have relatively narrow bandwidths, yielding slow recovery from output transients. The AD713 is ideally suited as a driver for A/D converters since it offers both a wide bandwidth and a high open loop gain. REV. C –9– AD713 Figure 12. Buffer Recovery Time Source Current = 2 mA Figure 15. Transient Response, RL = 2 kΩ, CL = 500 pF CMOS DAC APPLICATIONS The AD713 is an excellent output amplifier for CMOS DACs. It can be used to perform both 2 and 4 quadrant operation. The output impedance of a DAC using an inverted R-2R ladder approaches R for codes containing many “1”s, 3R for codes containing a single “1” and infinity for codes containing all zeros. For example, the output resistance of the AD7545 will modulate between 11 kΩ and 33 kΩ. Therefore, with the DAC’s internal feedback resistance of 11 kΩ, the noise gain will vary from 2 to 4/3. This changing noise gain modulates the effect of the input offset voltage of the amplifier, resulting in nonlinear DAC amplifier performance. The AD713, with its guaranteed 1.5 mV input offset voltage, minimizes this effect achieving 12-bit performance. Figures 16 and 17 show the AD713 and a 12-bit CMOS DAC, the AD7545, configured for either a unipolar binary (2-quadrant multiplication) or bipolar (4-quadrant multiplication) operation. Capacitor C1 provides phase compensation which reduces overshoot and ringing. Figure 13. Buffer Recovery Time Sink Current = 1 mA Driving A Large Capacitive Load The circuit of Figure 14 employs a 100 Ω isolation resistor which enables the amplifier to drive capacitive loads exceeding 1500 pF; the resistor effectively isolates the high frequency feedback from the load and stabilizes the circuit. Low frequency feedback is returned to the amplifier summing junction via the low pass filter formed by the 100 Ω series resistor and the load capacitance, C1. Figure 15 shows a typical transient response for this connection. Figure 16. Unipolar Binary Operation Figure 14. Circuit for Driving a Large Capacitance Load Table II. Recommended Trim Resistor Values vs. Grades for AD7545 for VD = 5 V Trim Resistor R1 R2 JN/AQ/ SD 500 Ω 150 Ω KN/BQ/ TD 200 Ω 68 Ω LN/CQ/ UD 100 Ω 33 Ω GLN/GCQ/ GUD 20 Ω 6.8 Ω Figure 17. Bipolar Operation –10– REV. C AD713 Figure 18. A Programmable State Variable Filter Circuit FILTER APPLICATIONS A Programmable State Variable Filter For the state variable or universal filter configuration of Figure 18 to function properly, DACs A1 and B1 need to control the gain and Q of the filter characteristic, while DACs A2 and B2 must accurately track for the simple expression of fC to be true. This is readily accomplished using two AD7528 DACs and one AD713 quad op amp. Capacitor C3 compensates for the effects of op amp gain-bandwidth limitations. This filter provides low pass, high pass and band pass outputs and is ideally suited for applications where microprocessor control of filter parameters is required. The programmable range for component values shown is fC = 0 to 15 kHz and Q = 0.3 to 4.5. GIC and FDNR FILTER APPLICATIONS 19 and 21 show the AD713 used in two typical active filters. The first shows a single AD713 simulating two coupled inductors configured as a one-third octave bandpass filter. A single section of this filter meets ANSI class II specifications and handles a 7.07 V rms signal with