Dual Low Bias Current Precision Operational Amplifier OP297 FEATURES PIN CONFIGURATION Low offset voltage: 50 μV maximum OUTA 1 8 V+ Low offset voltage drift: 0.6 μV/°C maximum –INA 2 A B 7 OUTB Very low bias current: 100 pA maximum +INA 3 6 –INB VLoewry s huipgphl oyp ceunrr-elonotp (p geari nam: 2p0l0if0ie Vr/)m: 6V2 5m μinAi mmuamxim um V– 4 5 +INB 00300-001 Operates from ±2 V to ±20 V supplies Figure 1. High common-mode rejection: 120 dB minimum APPLICATIONS 60 VS = ±15V Strain gage and bridge amplifiers VCM = 0V 40 High stability thermocouple amplifiers Instrumentation amplifiers PHhigohto gcauinrr elinnte maroitnyi atomrsp lifiers ENT (pA) 20 IB– Long-term integrators/filters CURR 0 IB+ Sample-and-hold amplifiers T U P–20 Peak detectors N Logarithmic amplifiers I IOS –40 Battery-powered systems GENERAL DESCRIPTION The OP297 is the first dual op amp to pack precision perform- –60–75 –50 –25 TE0MPERA25TURE (5°0C) 75 100 125 00300-002 ance into the space saving, industry-standard 8-lead SOIC Figure 2. Low Bias Current over Temperature package. The combination of precision with low power and extremely low input bias current makes the dual OP297 useful 400 in a wide variety of applications. 1200 UNITS TA = 25°C VS = ±15V Precision performance of the OP297 includes very low offset VCM = 0V (less than 50 μV) and low drift (less than 0.6 μV/°C). Open- 300 loop gain exceeds 2000 V/mV, ensuring high linearity in every TS NI application. U F Errors due to common-mode signals are eliminated by the R O200 E B common-mode rejection of over 120 dB, which minimizes M U offset voltage changes experienced in battery-powered systems. N 100 The supply current of the OP297 is under 625 μA. The OP297 uses a super-beta input stage with bias current ctcuaurnrercsee.n lTltasht isiost anirs tt io inn m c toahnient prtaaiicsnto tapomi cFpoE arTma nipng pbe iuaatts o 2cp5u° raCrme, npbtuss t wa dth oaoulslb etl eebm ifaopsr e ra- –0100 –80 –60 I–N4P0UT –O2F0FSET0 VOL2T0AGE 4(µ0V) 60 80 100 00300-003 Figure 3. Very Low Offset every 10°C rise in temperature, to reach the nanoamp range Combining precision, low power, and low bias current, the above 85°C. Input bias current of the OP297 is under 100 pA at OP297 is ideal for a number of applications, including instru- 25°C and is under 450 pA over the military temperature range mentation amplifiers, log amplifiers, photodiode preamplifiers, per amplifier. This part can operate with supply voltages as low and long term integrators. For a single device, see the OP97; for as ±2 V. a quad device, see the OP497. Rev. G 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Tel: 781.329.4700 www.analog.com Trademarks and registered trademarks are the property of their respective owners. Fax: 781.461.3113 ©2008 Analog Devices, Inc. All rights reserved.

OP297 TABLE OF CONTENTS Features .............................................................................................. 1  AC Performance ............................................................................9  Applications ....................................................................................... 1  Guarding and Shielding ................................................................9  General Description ......................................................................... 1  Open-Loop Gain Linearity ....................................................... 10  Pin Configuration ............................................................................. 1  Application Circuits ....................................................................... 11  Revision History ............................................................................... 2  Precision Absolute Value Amplifier ......................................... 11  Specifications ..................................................................................... 3  Precision Current Pump ............................................................ 11  Electrical Characteristics ............................................................. 3  Precision Positive Peak Detector .............................................. 11  Absolute Maximum Ratings ............................................................ 4  Simple Bridge Conditioning Amplifier ................................... 11  Thermal Resistance ...................................................................... 4  Nonlinear Circuits ...................................................................... 12  ESD Caution .................................................................................. 4  Outline Dimensions ....................................................................... 13  Typical Performance Characteristics ............................................. 5  Ordering Guide .......................................................................... 14  Applications Information ................................................................ 9  REVISION HISTORY 4/08—Rev. F to Rev. G 10/02—Rev. C to Rev. D Changes to Table 2 Conditions ....................................................... 3 Edits to Figure 16 ............................................................................... 6 Changes to Table 2 Power Supply Rejection Parameter .............. 3 Changes to Figure 5, Figure 6, Figure 7 ......................................... 5 10/02—Rev. B to Rev. C Changes to Figure 16 ........................................................................ 6 Edits to Specifications ....................................................................... 2 Updated Outline Dimensions ....................................................... 13 Deleted Wafer Test Limits ................................................................ 3 Changes to Ordering Guide .......................................................... 14 Deleted Dice Characteristics ............................................................ 3 Deleted Absolute Maximum Ratings .............................................. 4 2/06—Rev. E to Rev. F Edits to Ordering Guide ................................................................... 4 Updated Format .................................................................. Universal Updated Outline Dimensions ....................................................... 12 Changes to Features .......................................................................... 1 Deleted OP297 Spice Macro Model Section ................................. 9 Updated Outline Dimensions ....................................................... 13 Changes to Ordering Guide .......................................................... 14 7/03—Rev. D to Rev. E Changes to TPCs 13 and 16 ............................................................ 4 Edits to Figures 12 and 14 ............................................................... 8 Changes to Nonlinear Circuits Section ......................................... 8 Rev. G | Page 2 of 16

OP297 SPECIFICATIONS ELECTRICAL CHARACTERISTICS @ V = ±15 V, T = 25°C, unless otherwise noted. S A Table 1. OP297E OP297F OP297G Parameter Symbol Conditions Min Typ Max Min Typ Max Min Typ Max Unit Input Offset Voltage V 25 50 50 100 80 200 μV OS Long-Term Input Voltage 0.1 0.1 0.1 μV/month Stability Input Offset Current I V = 0 V 20 100 35 150 50 200 pA OS CM Input Bias Current I V = 0 V +20 ±100 +35 ±150 +50 ±200 pA B CM Input Noise Voltage e 0.1 Hz to 10 Hz 0.5 0.5 0.5 μV p-p np-p Input Noise Voltage Density e f = 10 Hz 20 20 20 nV/√Hz n OUT f = 1000 Hz 17 17 17 nV/√Hz OUT Input Noise Current Density i f = 10 Hz 20 20 20 fA/√Hz n OUT Input Resistance Differential Mode R 30 30 30 MΩ IN Common-Mode R 500 500 500 GΩ INCM Large Signal Voltage Gain A V = ±10 V, 2000 4000 1500 3200 1200 3200 V/mV VO OUT R = 2 kΩ L Input Voltage Range1 V ±13 ±14 ±13 ±14 ±13 ±14 V CM Common-Mode Rejection CMRR V = ±13 V 120 140 114 135 114 135 dB CM Power Supply Rejection PSRR V = ±2 V to 120 130 114 125 114 125 dB S ±20 V Output Voltage Swing V R = 10 kΩ ±13 ±14 ±13 ±14 ±13 ±14 V OUT L R = 2 kΩ ±13 ±13.7 ±13 ±13.7 ±13 ±13.7 V L Supply Current per Amplifier I No load 525 625 525 625 525 625 μA SY Supply Voltage V Operating range ±2 ±20 ±2 ±20 ±2 ±20 V S Slew Rate SR 0.05 0.15 0.05 0.15 0.05 0.15 V/μs Gain Bandwidth Product GBWP A = +1 500 500 500 kHz V Channel Separation CS V = 20 V p-p, 150 150 150 dB OUT f = 10 Hz OUT Input Capacitance C 3 3 3 pF IN 1 Guaranteed by CMR test. @ V = ±15 V, −40°C ≤ T ≤ +85°C, unless otherwise noted. S A Table 2. OP297E OP297F OP297G Parameter Symbol Conditions Min Typ Max Min Typ Max Min Typ Max Unit Input Offset Voltage V 35 100 80 300 110 400 μV OS Average Input Offset Voltage Drift TCV 0.2 0.6 0.5 2.0 0.6 2.0 μV/°C OS Input Offset Current I V = 0 V 50 450 80 750 80 750 pA OS CM Input Bias Current I V = 0 V +50 ±450 +80 ±750 +80 ±750 pA B CM Large Signal Voltage Gain A V = ±10 V, 1200 3200 1000 2500 800 2500 V/mV VO OUT R = 2 kΩ L Input Voltage Range1 V ±13 ±13.5 ±13 ±13.5 ±13 ±13.5 V CM Common-Mode Rejection CMRR V = ±13 114 130 108 130 108 130 dB CM Power Supply Rejection PSRR V = ±2.5 V to 114 108 108 dB S ±20 V Output Voltage Swing V R = 10 kΩ ±13 ±13.4 ±13 ±13.4 ±13 ±13.4 V OUT L Supply Current per Amplifier I No load 550 750 550 750 550 750 μA SY Supply Voltage V Operating range ±2.5 ±20 ±2.5 ±20 ±2.5 ±20 V S 1 Guaranteed by CMR test. Rev. G | Page 3 of 16

OP297 ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE Table 3. Parameter Rating θ is specified for worst-case mounting conditions, that is, θ JA JA Supply Voltage ±20 V is specified for device in socket for CERDIP and PDIP pack- Input Voltage1 ±20 V ages; θJA is specified for device soldered to printed circuit board Differential Input Voltage1 40 V for the SOIC package. Output Short-Circuit Duration Indefinite Table 4. Thermal Resistance Storage Temperature Range Package Type θ θ Unit Z-Suffix −65°C to +175°C JA JC 8-Lead CERDIP (Z-Suffix) 134 12 °C/W P-Suffix, S-Suffix −65°C to +150°C 8-Lead PDIP (P-Suffix) 96 37 °C/W Operating Temperature Range 8-Lead SOIC (S-Suffix) 150 41 °C/W OP297E (Z-Suffix) −40°C to +85°C OP297F, OP297G (P-Suffix, S-Suffix) −40°C to +85°C Junction Temperature ESD CAUTION Z-Suffix −65°C to +175°C P-Suffix, S-Suffix −65°C to +150°C Lead Temperature (Soldering, 60 sec) 300°C 1 For supply voltages less than ±20 V, the absolute maximum input voltage is equal to the supply voltage. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; 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. – 1/2 OP297 V1 20V p-p @ 10Hz + 2kΩ 50kΩ 50Ω – 1/2 OP297 V2 + CHANNEL SEPARATION = 20 log V2/1V01000 00300-004 Figure 4. Channel Separation Test Circuit Rev. G | Page 4 of 16

OP297 TYPICAL PERFORMANCE CHARACTERISTICS 400 60 1200 UNITS TA = 25°C VS = ±15V VS = ±15V VCM = 0V VCM = 0V 40 300 TS pA) 20 F UNI ENT ( IB– MBER O200 T CURR 0 IB+ NU NPU–20 100 I IOS –40 –0100 –80 –60 IN–P4U0T O–F20FSET0 VOLT2A0GE 4(µ0V) 60 80 100 00300-005 –60–75 –50 –25 TE0MPERA25TURE (5°0C) 75 100 125 00300-008 Figure 5. Typical Distribution of Input Offset Voltage Figure 8. Input Bias, Offset Current vs. Temperature 250 60 1200 UNITS TA = 25°C VS = ±15V VS = ±15V VCM = 0V 200 VCM = 0V 40 S A) IB– F UNIT150 ENT (p20 IB+ O R MBER 100 T CUR 0 U U N P IN IOS 50 –20 –0100 –80 –60 –IN4P0UT– B20IAS C0URRE2N0T (p4A0) 60 80 100 00300-006 –40–15 –10 COM–5MON-MOD0E VOLTAG5E (V) 10 15 00300-009 Figure 6. Typical Distribution of Input Bias Current Figure 9. Input Bias, Offset Current vs. Common-Mode Voltage 400 ±3 1200 UNITS TVVASC M== =2± 510°5VCV µV) TVVASC M== =2± 510°5VCV 300 UE ( L TS VA±2 NI L U A R OF 200 M FIN E O B R M F NU ON ±1 100 ATI VI E D –0100 –80 –60 IN–P4U0T O–F20FSET0 CURR2E0NT (4p0A) 60 80 100 00300-007 00 TI1ME AFTER P2OWER APPL3IED (Minute4s) 5 00300-010 Figure 7. Typical Distribution of Input Offset Current Figure 10. Input Offset Voltage Warm-Up Drift Rev. G | Page 5 of 16

OP297 10k 1300 BALANCED OR UNBALANCED VS = ±15V NO LOAD V) VCM = 0V AGE (µ T (µA)1200 TA = +125°C T 1k N L E O R V R1100 ET CU FS LY TA = +25°C F P FFECTIVE O 100 –55°C ≤ TA ≤ +125°C TOTAL SUP1090000 TA = –55°C E TA = +25°C 1010 100 SO1kURCE RE1S0IkSTANC1E0 (0Ωk) 1M 10M 00300-011 8000 ±5 SUPPLY V±O1L0TAGE (V) ±15 ±20 00300-014 Figure 11. Effective Offset Voltage vs. Source Resistance Figure 14. Total Supply Current vs. Supply Voltage 100 160 T (µV/°C) BVVSCA ML= A =±N 10C5VVED OR UNBALANCED B)140 VTAS == 2±51°5CV F d FSET VOLTAGE DRI 10 MODE REJECTION (112000 E OF 1 MON- 80 ECTIV COM 60 F F E 0.1100 1k S1O0UkRCE R1E0S0ISkTANCE1 M(Ω) 10M 100M 00300-012 401 10 100FREQUE1NkCY (Hz)10k 100k 1M 00300-015 Figure 12. Effective TCVOS vs. Source Resistance Figure 15. Common-Mode Rejection vs. Frequency 35 160 2350 TA = –55°C 140 TVAS == 2±51°5CV T (mA) 2105 TA = +25°C ON (dB)120 ΔVS = 10V p-p URREN 105 VS = ±15V TA = +125°C EJECTI100 C OUTPUT SHORTED R CIRCUIT –1–050 TO GROUND SUPPLY 80 RT-–15 TA = +125°C ER 60 O W SH–20 TA = +25°C PO –25 40 –30 TA = –55°C –350 TIM1E FROM OUTPU2T SHORT (Minu3tes) 4 00300-013 200.1 1 10 FR1E0Q0UENCY1 k(Hz) 10k 100k 1M 00300-016 Figure 13. Short-Circuit Current vs. Time, Temperature Figure 16. Power Supply Rejection vs. Frequency Rev. G | Page 6 of 16

OP297 1k 1k TA = 25°C V) RL = 10kΩ VS = ±2V TO ±15V DI VS = ±15V Y (nV/√Hz) 100 100 Y (fA/√Hz) AGE (10µV/ VCM = 0V TA = +125°C ENSIT CUNRORISEENT ENSIT VOLT TA = +25°C E D E D UT S S P 0 GE NOI 10 VONLOTISAEGE 10 NT NOI TIAL IN TA = –55°C LTA RRE REN O U E V C FF DI 11 10FREQUENCY (Hz)100 1k1 00300-017 –15 –10 –O5UTPUT VO0LTAGE (V5) 10 15 00300-020 Figure 17. Voltage Noise Density and Current Noise Density vs. Frequency Figure 20. Differential Input Voltage vs. Output Voltage 10 35 TA = 25°C TA = 25°C Hz) VS = ±2V TO ±20V 30 1VA%SV C =TL H ±=1D 5+V1 √ DENSITY (nV/ 1 10Hz WING (V p-p) 2205 fOUT = 1kHz E S OIS 1kHz UT 15 L N0.1 UTP A O 10 T O T 1kHz 5 10Hz 0.01100 1k SOUR1C0kE RESIST1A0N0CkE (Ω) 1M 10M 00300-018 010 1L0O0AD RESISTANCE (1Ωk) 10k 00300-021 Figure 18. Total Noise Density vs. Source Resistance Figure 21. Output Swing vs. Load Resistance 10k 35 TA = +25°C TA = –55°C VVSO U=T ± =1 5±V10V 30 TVAASV C==L 2± =51 °5+CV1 1% THD AIN (V/mV) TA = +125°C NG (V p-p) 2205 RfOLU =T 1=0 1kkΩHz N-LOOP G 1k TPUT SWI 15 E U P O 10 O 5 1001 2 LOA3D RE4SIST55ANC6E (7kΩ8) 910 20 00300-019 0100 1k FREQUENCY (Hz)10k 100k 00300-022 Figure 19. Open-Loop Gain vs. Load Resistance Figure 22. Maximum Output Swing vs. Frequency Rev. G | Page 7 of 16

OP297 100 1k VS = ±15V TA = 25°C 80 CRLL == 310MpΩF 100 VS = ±15V GAIN dB)60 ees) E (Ω) 10 OPEN-LOOP GAIN (24000 PHASE TA = –55°C 11983005 PHASE SHIFT (Degr OUTPUT IMPEDANC 0.11 0.01 –20 225 TA = +125°C –40100 1k F1R0kEQUENCY1 0(H0kz) 1M 10M270 00300-023 0.00110 100 FR1EkQUENCY 1(H0zk) 100k 1M 00300-025 Figure 23. Open-Loop Gain, Phase vs. Frequency Figure 25. Open-Loop Output Impedance vs. Frequency 70 TA = 25°C 60 VASV C=L ±=1 5+V1 VOUT = 100mV p-p –EDGE 50 %) T (40 O O +EDGE H S R30 E V O 20 10 010 L1O0A0D CAPACITANCE 1(pkF) 10k 00300-024 Figure 24. Small Signal Overshoot vs. Load Capacitance Rev. G | Page 8 of 16

OP297 APPLICATIONS INFORMATION Extremely low bias current over a wide temperature range makes the OP297 attractive for use in sample-and-hold amplifiers, peak detectors, and log amplifiers that must operate 100 over a wide temperature range. Balancing input resistances is 90 unnecessary with the OP297. Offset voltage and TCV are OS degraded only minimally by high source resistance, even when unbalanced. The input pins of the OP297 are protected against large differen- tial voltage by back-to-back diodes and current-limiting resistors. 10 Common-mode voltages at the inputs are not restricted and can 0% vTahrey OovPe2r9 t7h ree fquulli rreasn vgeer oyf l itthtlee s ouppeprlayt ivnoglt hageeasd ruosoemd. about the 20mV 5µs 00300-028 Figure 28. Large Signal Transient Response (AVCL = +1) supply rails and is specified for operation with supplies as low as GUARDING AND SHIELDING 2 V. Typically, the common-mode range extends to within 1 V of either rail. The output typically swings to within 1 V of the To maintain the extremely high input impedances of the OP297, rails when using a 10 kΩ load. care is taken in circuit board layout and manufacturing. Board AC PERFORMANCE surfaces must be kept scrupulously clean and free of moisture. Conformal coating is recommended to provide a humidity The ac characteristics of the OP297 are highly stable over its full barrier. Even a clean PCB can have 100 pA of leakage currents operating temperature range. Unity gain small signal response is between adjacent traces, therefore guard rings should be used shown in Figure 26. Extremely tolerant of capacitive loading on around the inputs. Guard traces operate at a voltage close to that the output, the OP297 displays excellent response with 1000 pF on the inputs, as shown in Figure 29, to minimize leakage loads (see Figure 27). currents. In noninverting applications, the guard ring should be connected to the common-mode voltage at the inverting input. In inverting applications, both inputs remain at ground, so the guard trace should be grounded. Guard traces should be placed 100 90 on both sides of the circuit board. UNITY-GAIN FOLLOWER NONINVERTINGAMPLIFIER 10 – – 10 1/2 1/2 0% OP297 OP297 + + 20mV 5µs 00300-026 Figure 26. Small Signal Transient Response (CL = 100 pF, AVCL = +1) MINI-DIP INVERTINGAMPLIFIER BOTTOM VIEW 8 1 100 90 A – 1/2 B OP297 + 00300-029 Figure 29. Guard Ring Layout and Considerations 10 0% 20mV 5µs 00300-027 Figure 27. Small Signal Transient Response (CL = 1000 pF, AVCL = +1) Rev. G | Page 9 of 16

OP297 OPEN-LOOP GAIN LINEARITY V) RL = 10kΩ The OP297 has both an extremely high gain of 2000 V/mV µV/DI VVSC M= =± 105VV mprienciimsiounm o af nthde c OonPs2ta9n7t a gnadin p lrionveiadreitsy f.o Tr hviesr eyn hhiagnhc aecsc tuhrea cy in GE (10 TA = +125°C A high closed-loop gain applications. Figure 30 illustrates the LT typical open-loop gain linearity of the OP297 over the military T VO TA = +25°C U temperature range. P 0 N AL I TA = –55°C TI N E R E F F DI –15 –10 –O5UTPUT VO0LTAGE (V5) 10 15 00300-030 Figure 30. Open-Loop Linearity of the OP297 Rev. G | Page 10 of 16

OP297 APPLICATION CIRCUITS PRECISION ABSOLUTE VALUE AMPLIFIER PRECISION POSITIVE PEAK DETECTOR The circuit in Figure 31 is a precision absolute value amplifier In Figure 33, the C must be of polystyrene, Teflon®, or H with an input impedance of 30 MΩ. The high gain and low polyethylene to minimize dielectric absorption and leakage. TCV of the OP297 ensure accurate operation with microvolt The droop rate is determined by the size of C and the bias OS H input signals. In this circuit, the input always appears as a current of the OP297. common-mode signal to the op amps. The CMR of the OP297 1kΩ exceeds 120 dB, yielding an error of less than 2 ppm. +15V +15V 1N4148 0.1µF C2 2 0.1µF – 1Rk1Ω 1Rk3Ω VIN 1kΩ 3 +OP1/2297 1 6 O–P1/2297 7 VOUT 1kΩ 5 + 2 –OP1/2289730CpF11 D1N14148 56 +–OP1/2297 07V < VOUT < 10V RESET 1kΩ CH 2N930 –15V0.1µF 00300-033 VIN 3 + C3 1ND41248 R2 Figure 33. Precision Positive Peak Detector 0.1µF 2kΩ SIMPLE BRIDGE CONDITIONING AMPLIFIER 4 –15V 00300-031 Fthigeu OreP 2349 7s.h Tohwes tar asnimsfperle f ubnricdtgioen c oisn ditioning amplifier using Figure 31. Precision Absolute Value Amplifier ⎛ ΔR ⎞R PRECISION CURRENT PUMP VOUT =VREF⎜⎝R+ΔR⎟⎠ RF Maximum output current of the precision current pump shown The REF43 provides an accurate and stable reference voltage for in Figure 32 is ±10 mA. Voltage compliance is ±10 V with the bridge. To maintain the highest circuit accuracy, R should F ±15 V supplies. Output impedance of the current transmitter be 0.1% or better with a low temperature coefficient. exceeds 3 MΩ with linearity better than 16 bits. R1 through R4 15V should be matched resistors. 10Rk3Ω VREF RF REF43 2 R1 – 10kΩ 2 – R5 4 R +ΔR OP1/2297 1 VOUT VIN 10Rk2Ω 3 OP1/2297 1 100kΩ 1IO0UmTA MAX 3 + + +15V 10Rk4Ω 7 1/82+ 5 IOUT = VR I 5N = 1 V0 0I N Ω = 10mA/V 6 O–P1/22897 7 VOUT = VREF R Δ+RΔR RRF OP297 5 – 6 + 4 00300-034 Figure 34. Simple Bridge Condition Amplifier Using the OP297 –15V 00300-032 Figure 32. Precision Current Pump Rev. G | Page 11 of 16

OP297 NONLINEAR CIRCUITS R2 33kΩ Due to its low input bias currents, the OP297 is an ideal log C2 100pF amplifier in nonlinear circuits such as the square and square root circuits shown in Figure 35 and Figure 36. Using the 6 – sbqyu warriintign gc iar cvuoiltt aogf eF lioguopre e 3q5u aatsi oann eaxcraomssp lTer, atnhsei satnoarl yQs1is, begins IOUT 5 OP1/2297 7 VOUT + IREF Transistor Q2, Transistor Q3, and Transistor Q4. 1 MAT04E ⎛I ⎞ ⎛I ⎞ ⎛I ⎞ ⎛I ⎞ Q1 VT1ln⎜⎜⎝ IISN1 ⎟⎟⎠+VT2ln⎜⎜⎝IISN2 ⎟⎟⎠=VT3ln⎜⎜⎝ IOSU3T ⎟⎟⎠+VT4ln⎜⎜⎝ IRSE4F ⎟⎟⎠ 10C01pF 3 13 Q41142 7 8 All the transistors of the MAT04 are precisely matched and at V+ 6 Q2 Q3 9 the same temperature, so the I and V terms cancel, where R1 5 10 S T 2lnIIN = lnIOUT + lnIREF = ln(IOUT × IREF) VIN 33kΩ 2 –1/28 1 50Rk3Ω OP297 Exponentiating both sides of the equation leads to 3 + 4 R504kΩ I =(IIN)2 V– –15V 00300-036 OUT I Figure 36. Square Root Amplifier REF In these circuits, I is a function of the negative power supply. Op Amp A2 forms a current-to-voltage converter, which gives REF To maintain accuracy, the negative supply should be well regu- V = R2 × I . Substituting (V /R1) for I and the previous OUT OUT IN IN lated. For applications where very high accuracy is required, a equation for I yields OUT voltage reference can be used to set I . REF ⎛ R2 ⎞⎛V ⎞2 V =⎜ ⎟⎜ IN ⎟ An important consideration for the squaring circuit is that a OUT ⎜⎝IREF ⎟⎠⎝ R1 ⎠ sufficiently large input voltage can force the output beyond the A similar analysis made for the square root circuit of Figure 36 operating range of the output op amp. Resistor R4 can be leads to its transfer function changed to scale IREF or R1; R2 can be varied to keep the output voltage within the usable range. ( )( ) V I V =R2 IN REF Unadjusted accuracy of the square root circuit is better than OUT R1 0.1% over an input voltage range of 100 mV to 10 V. For a C2 similar input voltage range, the accuracy of the squaring circuit 100pF is better than 0.5%. R2 33kΩ 6 – IOUT OP1/2297 7 VOUT 2 1 5 + Q1 3 6 7 Q2 5 MAT04E 14 10C01pF V+ 8Q3 9 IREF 1Q24 13 R1 10 VIN 33kΩ 2 –1/28 1 50Rk3Ω OP297 3 R4 + 4 50kΩ V– –15V 00300-035 Figure 35. Squaring Amplifier Rev. G | Page 12 of 16

OP297 OUTLINE DIMENSIONS 0.400 (10.16) 0.365 (9.27) 0.355 (9.02) 8 5 0.280 (7.11) 0.250 (6.35) 1 4 0.240 (6.10) 0.325 (8.26) 0.310 (7.87) 0.100 (2.54) 0.300 (7.62) BSC 0.060 (1.52) 0.195 (4.95) 0.210 (5.33) MAX 0.130 (3.30) MAX 0.115 (2.92) 0.015 0.150 (3.81) (0.38) 0.015 (0.38) 0.130 (3.30) MIN GAUGE 0.115 (2.92) SEATING PLANE 0.014 (0.36) PLANE 0.010 (0.25) 0.022 (0.56) 0.008 (0.20) 0.005 (0.13) 0.430 (10.92) 0.018 (0.46) MIN MAX 0.014 (0.36) 0.070 (1.78) 0.060 (1.52) 0.045 (1.14) COMPLIANTTO JEDEC STANDARDS MS-001 CONTROLLING DIMENSIONSARE IN INCHES; MILLIMETER DIMENSIONS (RCINEOFRPEANRERERENN LCTEEHA EODSNSEL MSY)AAAYNR BDEE AR CROOEU NNNFODIGETUDAR-POEPFDRFOA INSPC RWHIAH ETOEQL UFEIO VORAR LU EHSNAETL ISFN FLDOEEARSDIGSN.. 070606-A Figure 37. 8-Lead Plastic Dual In-Line Package [PDIP] P-Suffix (N-8) Dimensions shown in inches and (millimeters) 0.005 (0.13) 0.055 (1.40) MIN MAX 8 5 0.310 (7.87) 0.220 (5.59) 1 4 0.100 (2.54) BSC 0.405 (10.29) MAX 0.320 (8.13) 0.290 (7.37) 0.200 (5.08) 0.060 (1.52) MAX 0.015 (0.38) 0.200 (5.08) 0.150 (3.81) MIN 0.125 (3.18) 0.015 (0.38) 00..002134 ((00..5386)) 0.070 (1.78) SPELAANTIENG 1 05°° 0.008 (0.20) 0.030 (0.76) CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. Figure 38. 8-Lead Ceramic Dual In-Line Package [CERDIP] Z-Suffix (Q-8) Dimensions shown in inches and (millimeters) Rev. G | Page 13 of 16

OP297 5.00(0.1968) 4.80(0.1890) 8 5 4.00 (0.1574) 6.20 (0.2441) 3.80 (0.1497) 1 4 5.80 (0.2284) 1.27 (0.0500) 0.50 (0.0196) BSC 1.75 (0.0688) 0.25 (0.0099) 45° 0.25 (0.0098) 1.35 (0.0532) 8° 0.10 (0.0040) 0° COPLANARITY 0.51 (0.0201) 0.10 SEATING 0.31 (0.0122) 0.25 (0.0098) 10..2470 ((00..00510507)) PLANE 0.17 (0.0067) COMPLIANTTO JEDEC STANDARDS MS-012-AA C(RINOEFNPETARRREOENNLCLTEIHN EOGSN DELSIYM)AEANNRDSEI AORRNOESU NANORDEET DAIN-PO MPFRIFLO LMPIIMRLELIATIMTEEER TFSEO; RIRN ECUQHSU EDI VIINMA LEDENENSSTIIOGSN NFS.OR 012407-A Figure 39. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body S-Suffix (R-8) Dimensions shown in millimeters and (inches) ORDERING GUIDE Model Temperature Range Package Description Package Options OP297EZ −40°C to +85°C 8-Lead CERDIP Q-8 (Z-Suffix) OP297FP −40°C to +85°C 8-Lead PDIP N-8 (P-Suffix) OP297FPZ1 −40°C to +85°C 8-Lead PDIP N-8 (P-Suffix) OP297FS −40°C to +85°C 8-Lead SOIC_N R-8 (S-Suffix) OP297FS-REEL −40°C to +85°C 8-Lead SOIC_N R-8 (S-Suffix) OP297FS-REEL7 −40°C to +85°C 8-Lead SOIC_N R-8 (S-Suffix) OP297FSZ1 −40°C to +85°C 8-Lead SOIC_N R-8 (S-Suffix) OP297FSZ-REEL1 −40°C to +85°C 8-Lead SOIC_N R-8 (S-Suffix) OP297FSZ-REEL71 −40°C to +85°C 8-Lead SOIC_N R-8 (S-Suffix) OP297GP −40°C to +85°C 8-Lead PDIP N-8 (P-Suffix) OP297GPZ1 −40°C to +85°C 8-Lead PDIP N-8 (P-Suffix) OP297GS −40°C to +85°C 8-Lead SOIC_N R-8 (S-Suffix) OP297GS-REEL −40°C to +85°C 8-Lead SOIC_N R-8 (S-Suffix) OP297GS-REEL7 −40°C to +85°C 8-Lead SOIC_N R-8 (S-Suffix) OP297GSZ1 −40°C to +85°C 8-Lead SOIC_N R-8 (S-Suffix) OP297GSZ-REEL1 −40°C to +85°C 8-Lead SOIC_N R-8 (S-Suffix) OP297GSZ-REEL71 −40°C to +85°C 8-Lead SOIC_N R-8 (S-Suffix) 1 Z = RoHS Compliant Part. Rev. G | Page 14 of 16

OP297 NOTES Rev. G | Page 15 of 16

OP297 NOTES ©2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D00300-0-4/08(G) Rev. G | Page 16 of 16

Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: A nalog Devices Inc.: OP297GSZ OP297GS OP297FS-REEL7 OP297FS OP297EZ OP297FSZ-REEL OP297GSZ-REEL7 OP297GS- REEL7 OP297GSZ-REEL OP297FPZ OP297GPZ OP297FSZ OP297FSZ-REEL7 OP297GS-REEL