Precision Operational Amplifiers for Sensor Signal Chains
Product Specifications
Product Overview
In a sensor signal chain the amplifier is usually the part that limits the measurement. Offset voltage sets the usable range before trimming, offset drift decides whether the reading is stable over temperature, and input bias current sets the maximum source impedance that can be used. For a strain gauge, a thermocouple, a photodiode or a current shunt, those three numbers are chosen first and the rest of the chain is built around them.
This page covers the precision amplifier families requested most often for that job: the ADI OPx177 series with 60 uV maximum offset and 0.7 uV per degree drift, the Texas Instruments OPA2211 and OPA2188 with very low noise and zero drift respectively, plus the general purpose LM358 and LM324 that appear on almost every control board as a comparator, buffer or level shifter.
All models are grouped into this single product, so a signal chain enquiry can include the amplifier, the instrumentation amplifier, the ADC driver and the reference for the same channel in one quote.
Electrical Specifications
| Parameter | OP2177 / OP4177 (ADI) | OPA2211 (TI) | OPA2188 (TI) | LM358 / LM324 |
|---|---|---|---|---|
| Channel count | Dual (OP2177), quad (OP4177) | Dual | Dual | Dual (LM358), quad (LM324) |
| Offset voltage | 60 uV maximum (OP1177/OP2177), 0.7 uV per degree maximum drift | 25 uV maximum | 6 uV maximum, 0.03 uV per degree drift | 2 mV to 7 mV typical, not a precision part |
| Input bias current | 2 nA maximum | not a bias current oriented part | 160 pA typical on the zero drift design | 20 nA typical |
| Noise | 8 nV per root Hz typical | 1.1 nV per root Hz at 1 kHz | 8.8 nV per root Hz | 40 nV per root Hz typical |
| Supply range | plus/minus 2.5 V to plus/minus 15 V (5 V to 30 V total) | plus/minus 2.25 V to plus/minus 18 V (4.5 V to 36 V) | 4.5 V to 36 V, single or dual supply | 3 V to 32 V single supply |
| Supply current | 400 uA per amplifier typical | about 3.6 mA per channel | about 0.9 mA per channel | about 0.7 mA per amplifier |
| CMRR / PSRR | greater than 120 dB minimum | greater than 126 dB | greater than 130 dB | 65 dB to 80 dB typical |
| Temperature range | -40 C to +125 C, specified over the full range in MSOP and SOIC | industrial grade to +125 C | industrial grade to +125 C | -40 C to +85 C |
| Packages | 8-lead MSOP and SOIC (dual), 14-lead SOIC and TSSOP (quad) | 8-lead SOIC with PowerPAD, dual | 8-lead SOIC, dual | 8-lead SOIC (dual), 14-lead SOIC (quad) |
Included Models and Order Codes
The order codes below include the package suffix, because the ADI and TI precision families are offered in both MSOP and SOIC with identical electrical specifications but different thermal behaviour and board area.
| Model | Channels | Key Specs | Supply | Package | Notes |
|---|---|---|---|---|---|
| OP2177ARZ | Dual | 60 uV maximum offset, 0.7 uV per degree drift, 8 nV per root Hz, 2 nA maximum bias current | plus/minus 2.5 V to plus/minus 15 V | SOIC-8 | Low noise precision dual for transducer front ends |
| OP2177ARMZ | Dual | Same electrical specification as OP2177ARZ | plus/minus 2.5 V to plus/minus 15 V | MSOP-8 | Same performance in a smaller footprint, tape and reel |
| OP4177ARUZ | Quad | Same per amplifier specification as the OP2177 | plus/minus 2.5 V to plus/minus 15 V | TSSOP-14 | Four channels for multi sensor boards |
| OP297GSZ | Dual | Low bias current precision dual, 50 uV class offset | plus/minus 4 V to plus/minus 20 V | SOIC-8 | Widely used in instrumentation front ends |
| OPA2211AIDDAR | Dual | 1.1 nV per root Hz at 1 kHz, 25 uV maximum offset | plus/minus 2.25 V to plus/minus 18 V | SOIC-8 PowerPAD | Very low noise for high gain sensor channels |
| OPA2188AIDR | Dual | Zero drift, 0.03 uV per degree, 6 uV maximum offset, 8.8 nV per root Hz | 4.5 V to 36 V | SOIC-8 | Drift critical channels such as load cells and thermocouples |
| OPA2197IDR | Dual | Rail to rail input and output, low offset, 20 MHz class bandwidth | 4.5 V to 36 V | SOIC-8 | ADC driver and active filter stages |
| OPA320AIDBVR | Single | 20 MHz, rail to rail input and output, low noise CMOS | 1.8 V to 5.5 V | SOT-23-5 | Low voltage sensor interfaces |
| OPA1678IDR | Dual | Low noise audio grade operational amplifier | 4.5 V to 36 V | SOIC-8 | Audio and low frequency signal paths |
| ADA4807-2ARMZ | Dual | Low power, low noise, low distortion | 3 V to 10 V | MSOP-8 | Fast settling ADC driver |
| LM358DR | Dual | General purpose, 3 mV class offset, single supply | 3 V to 32 V | SOIC-8 | Buffer, comparator and level shift duties on control boards |
| LM324DR | Quad | General purpose, single supply, four channels | 3 V to 32 V | SOIC-14 | Multiple low precision channels on one board |
| INA226AIDGSR | Current sense monitor | Current and bus voltage monitor with I2C output | 2.7 V to 5.5 V | VSSOP-10 | Power and load current monitoring alongside the signal chain |
| INA240A1PWR | Current sense amplifier | Bidirectional current sense amplifier with enhanced PWM rejection | 2.7 V to 5.5 V | TSSOP-8 | Motor and solenoid current measurement |
Key Features
Low Offset And Low Drift – Maximum offset figures and drift in microvolts per degree are stated per part, so a channel can be budgeted for temperature without trimming.
Low Input Bias Current – Nanopamp to nanoamp class bias current on the precision parts, which allows high source impedance sensors such as photodiodes and pH probes.
Noise Specified At Frequency – Noise density in nanovolts per root hertz so the achievable resolution of a gain stage can be calculated before the board is built.
Zero Drift Options – Chopper stabilised parts for channels where offset drift, not offset, sets the error budget over temperature.
Single And Dual Supply – Parts that run from a 3 V to 36 V single rail as well as from plus/minus supplies, which suits both battery powered and rack equipment.
Full Temperature Specification – Precision parts specified over -40 C to +125 C in the surface mount packages, not only at 25 C.
Package And Channel Options – Single, dual and quad versions in SOT-23, MSOP, SOIC and TSSOP, so a multi channel board can use one part family throughout.
Applications
Channels and boards that use these amplifiers: Signal chain parts are frequently quoted together with the SUPERB PCB and SUPERB PCBA work we support for the same measurement board.
Sensor Signal Conditioning – Bridge, thermocouple, RTD and photodiode front ends where offset, drift and bias current set the achievable accuracy.
Instrumentation And Measurement – Data acquisition channels, 4-20 mA receivers and precision voltage and current measurement circuits.
Medical And Laboratory Equipment – Low noise amplification ahead of a high resolution ADC in diagnostic and laboratory instruments.
Industrial Control Feedback – Current and voltage feedback loops, transducer interfaces and active filters on control and drive boards.
Sourcing and Cross-Reference
Amplifier substitution is a signal chain decision rather than a part number decision, so a cross reference only makes sense when the whole channel is compared: offset, drift, bias current, noise density, minimum supply voltage, input and output swing and the package pin out. Where two parts differ in one of those numbers in a way that matters for the channel, we say which one and leave the decision with you rather than presenting the substitute as equivalent.
The precision amplifier market is also where counterfeits concentrate, because the difference between a good part and a remarked one is invisible until the offset drift is measured over temperature. We state the marking, the condition and the packing on the quote, and can supply sealed original stock where the build requires a documented source.
Where the board is assembled in volume, SUPERB Assembly support covers the SMT build of the analog section.
Q: Can you supply pin-to-pin replacement equivalents for discontinued precision amplifiers?
A: Yes. Send the part number, the package and the quantity and the SUPERB Tech sales team will reply with availability, marking information and the nearest equivalent for the channel.
Why Source Precision Amplifiers from Superb Automation?
- Analog Signal Chain Focus: Operational amplifiers, instrumentation amplifiers, current sense parts, references and ADC drivers handled as one group.
- Specification Level Comparison: Offset, drift, bias current, noise and supply range compared per part, because those are the numbers that decide whether a substitute works.
- Counterfeit Risk Control: Primary source, marking and condition stated on every quote for parts that are commonly re marked.
- Discontinued And Obsolete Support: Mature amplifier families sourced from verified stock for repair and for boards that cannot be redesigned.
- Channel Level Kitting: Amplifier, instrumentation amplifier, reference and ADC for one channel quoted together to match your design blocks.
- Engineering Level Reply: Questions about noise, drift and supply headroom answered against the data sheet rather than from a summary.
Related Product Families
This page is part of the component range we supply for industrial, telecom, medical and defence builds. Continue with: Amplifiers and Comparators, Analog and Mixed-Signal ICs, Sensors and Detectors, ADI limiting amplifier chips.