OPA132U - 8MHz FET-Input Op Amp, Single, 8-SOIC | Texas Instruments
MPN: OPA132U ✓ ActiveOPA132U Overview
An operational amplifier (op amp) is a high-gain differential voltage amplifier that uses external feedback components to set closed-loop behavior such as gain, filtering, and signal conditioning. FET-input op amps use a junction field-effect transistor at the input stage rather than a bipolar transistor, delivering input bias currents orders of magnitude lower than their BJT counterparts. The OPA132 belongs to the SoundPlus audio op-amp family and sits in the broader hierarchy of linear ICs → amplifiers → operational amplifiers → precision audio op amps.
Key features include a 130 dB open-loop gain (600 Ω load), 500 µV maximum offset voltage, 0.00008 % total harmonic distortion, and 5 pA maximum input bias current. The FET input stage enables direct interface to high-impedance sensors, photodiodes, and electret microphones without requiring bias-current compensation networks. Its 20 V/µs slew rate and 8 MHz gain-bandwidth product make it equally suitable for fast-settling data-acquisition front ends and low-noise audio signal paths.
The OPA132 uses a complementary bipolar-FET input stage followed by a high-gain second stage and a class AB output, providing rail-swing to within ~1.5 V of either supply on 600 Ω loads. The architecture is unity-gain stable and includes internal ESD protection on all pins. Single, dual (OPA2132), and quad (OPA4132) versions share identical specifications for maximum design flexibility across channel counts.
Typical applications include professional audio line drivers and headphone buffers, photodiode and pH-probe transimpedance amplifiers, high-impedance sensor signal conditioning, 16-bit and 18-bit ADC input buffers, and active filters for instrumentation. The 8-SOIC footprint and industry-standard pinout simplify PCB layout in both new designs and legacy upgrades.
When designing with the OPA132U, place a 100 nF decoupling capacitor within 5 mm of each supply pin and use a ground plane to minimize parasitic inductance. For audio applications, keep input traces short and guarded to preserve the FET input's ultra-low bias current and avoid leakage paths on the PCB surface.
This page synthesizes distributor pricing, drop-in SOIC-8 alternatives, and practical design notes not consolidated on the manufacturer datasheet, giving engineers a single reference for part selection, layout, and second-source decisions.
Drop-in alternatives for OPA132U — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with OPA132U (same form factor and footprint) — differing in Package, Series, Slew Rate.
OPA2132U
✅ Drop-In📋 Reference alternative (not in catalog)
OPA131U
✅ Drop-InContact for price
View Datasheet →OPA627AUA
✅ Drop-In📋 Reference alternative (not in catalog)
TL081IDR
✅ Drop-In📋 Reference alternative (not in catalog)
AD711KRZ
✅ Drop-In📋 Reference alternative (not in catalog)
AD744KRZ
✅ Drop-In📋 Reference alternative (not in catalog)
OPA132U Maximum Ratings & Electrical Characteristics
| Amplifier Type | FET-Input Operational Amplifier |
| Number of Channels | 1 (Single) |
| Gain Bandwidth Product | 8 MHz |
| Slew Rate | 20 V/µs |
| Input Bias Current (max) | 50 pA |
| Input Offset Voltage (max) | 500 µV |
| Open-Loop Gain (600 Ω load) | 130 dB |
| Total Harmonic Distortion | 0.00008 % |
| Supply Voltage Range (Dual) | ±2.25 V to ±18 V |
| Supply Voltage Range (Single) | 4.5 V to 36 V |
| Operating Temperature Range | -40 °C to +85 °C |
| Output Type | Rail-to-Rail (approaching rails on 600 Ω) |
| Package | 8-pin SOIC (D) |
| Mounting Type | Surface Mount |
| MSL Level | 3 (168 hours) |
| RoHS Status | Compliant |
| Series | SoundPlus, OPAx132 |
OPA132U Pin Configuration
| Pin 1 | Offset Null — Offset trim pin (leave open or connect to wiper of 10 kΩ trim pot) |
| Pin 2 | -IN — Inverting input |
| Pin 3 | +IN — Non-inverting input |
| Pin 4 | V- — Negative supply voltage |
| Pin 5 | Offset Null — Offset trim pin (leave open or connect to wiper of 10 kΩ trim pot) |
| Pin 6 | OUTPUT — Amplifier output |
| Pin 7 | V+ — Positive supply voltage |
| Pin 8 | NC — Not connected (per datasheet) |
Typical Applications
OPA132U is suitable for 6 applications: Professional Audio Line Driver, Photodiode Transimpedance Amplifier, High-Impedance Sensor Signal Conditioning, 16/18-bit ADC Input Buffer, Active Filter for Instrumentation, Electret Microphone Preamplifier.
Professional Audio Line Driver
The OPA132U's 8 MHz gain-bandwidth product and 20 V/µs slew rate let it drive 600 Ω audio lines cleanly without slew-induced distortion in the audio band. Its 0.00008 % THD specification and 130 dB open-loop gain deliver transparent signal amplification for studio-grade line outputs and headphone amplifiers. The 5 pA FET input bias current also makes the part tolerant of high-impedance source networks used in passive volume controls.
Recommended
Photodiode Transimpedance Amplifier
The OPA132U's 5 pA maximum input bias current is two to three orders of magnitude lower than typical photodiode dark currents, letting the part amplify silicon and InGaAs photodiode signals without bias-current compensation. The 8 MHz bandwidth supports transimpedance values up to several MΩ with closed-loop bandwidths in the hundreds of kHz. Designers should add a small feedback capacitor (typically 1-5 pF) to control peaking and ensure unity-gain stability.
Recommended
High-Impedance Sensor Signal Conditioning
The OPA132U's FET input stage delivers 50 pA maximum bias current and low voltage noise, making it ideal for buffering pH probes, conductivity sensors, and piezoelectric transducers. Its ±18 V supply range accommodates the higher analog rails common in industrial sensor conditioning. PCB layout should use guard rings around the input traces to prevent leakage paths that would otherwise compromise the FET input's low-bias advantage.
Recommended
16/18-bit ADC Input Buffer
The OPA132U's 8 MHz bandwidth and 20 V/µs slew rate make it a strong fit as a unity-gain buffer in front of precision successive-approximation ADCs up to 18 bits, where settling time directly determines conversion accuracy. The 130 dB open-loop gain (600 Ω load) keeps gain error below 1 ppm at DC, and the FET input avoids the bias-current-induced voltage errors that bipolar-input op amps would introduce. Place the OPA132U within 50 mm of the ADC input to preserve signal integrity.
Recommended
Active Filter for Instrumentation
The OPA132U's 8 MHz GBW gives designers roughly 800 kHz of usable closed-loop bandwidth at unity gain, comfortably supporting multi-pole Sallen-Key and multiple-feedback active filters in the audio and ultrasonic bands. Its 20 V/µs slew rate ensures clean transient response in band-pass and high-Q filter topologies. The standard single-op-amp SOIC-8 pinout simplifies board layout in mixed-signal instrumentation designs.
Recommended
Electret Microphone Preamplifier
The OPA132U's ultra-low 5 pA input bias current and high input impedance (>10^13 Ω) make it an excellent preamp for electret condenser microphones, where source impedance is typically 1-10 GΩ. The 8 MHz bandwidth covers the full audio band plus ultrasonic headroom, and the low 0.00008 % THD preserves the microphone's signal integrity. The SOIC-8 footprint allows the preamp to fit inside compact microphone housings and XLR adapter boards.
Recommended
Recommended Products Summary
Engineering reference data for OPA132U — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | OPA2132U | OPA131U | AD711KRZ | AD744KRZ |
|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Analog Devices | Analog Devices |
| Package | 8-SOIC (D) | 8-SOIC (D) - same | 8-SOIC (D) - same | 8-SOIC (D) - same | 8-SOIC (D) - same |
| Channels | 1 (Single) | 2 (Dual) | 1 (Single) | 1 (Single) | 1 (Single) |
| Gain Bandwidth Product | 8 MHz | 8 MHz | 4 MHz | 3 MHz | 13 MHz |
| Slew Rate | 20 V/µs | 20 V/µs | 10 V/µs | 20 V/µs | 75 V/µs |
| Input Bias Current (max) | 50 pA | 50 pA | 50 pA | 25 pA | 30 pA |
| Input Offset Voltage (max) | 500 µV | 500 µV | 750 µV | 500 µV | 500 µV |
| Supply Voltage Range (Dual) | ±2.25 V to ±18 V | ±2.25 V to ±18 V | ±2.25 V to ±18 V | ±4.5 V to ±18 V | ±4.5 V to ±18 V |
| RoHS Compliance | Compliant | Compliant | Compliant | Compliant | Compliant |
Key Differentiators
- Higher bandwidth and slew rate than the OPA131U predecessor (vs OPA131U)
- Dual-channel version with identical specs for stereo designs (vs OPA2132U)
- Cross-brand drop-in alternative with wider bandwidth (vs AD744KRZ)
Design Notes
Place a 100 nF ceramic decoupling capacitor within 5 mm of each supply pin (V+ and V-), and add a 10 µF tantalum or aluminum bulk capacitor at the supply entry point. Use a continuous ground plane under the SOIC-8 footprint to minimize parasitic inductance and provide thermal spreading. For high-impedance sensor applications, surround the input traces with a guard ring tied to a low-impedance node at the same potential as the inputs to prevent surface leakage from degrading the FET input's 5 pA bias specification.
The OPA132U's FET input stage is highly sensitive to PCB leakage paths, so clean the board with isopropyl alcohol after soldering and consider a flux-residue-free assembly process. For transimpedance amplifier designs, keep the feedback resistor (Rf) and any feedback capacitor (Cf) as close to the inverting input pin as possible - stray capacitance at this node is the leading cause of TIA instability. Typical Cf values range from 1-5 pF to provide 45° phase margin at the desired closed-loop bandwidth.
Estimated: at maximum supply of ±18 V with a 600 Ω load drawing 30 mA peak, the OPA132U dissipates roughly 1.08 W worst case. The 8-SOIC package has a thermal resistance of approximately 150 °C/W junction-to-ambient, so the junction would rise about 160 °C above ambient. In practice, audio applications rarely approach this dissipation because the output stage operates in class AB with low quiescent current (~2 mA). For high-output-current applications, ensure the layout uses copper pours on both top and bottom layers to spread heat.
Do not connect the Offset Null pins (1 and 5) directly to ground or V+ - if offset trimming is not needed, leave them open. Connecting a 10 kΩ potentiometer between pins 1 and 5 with the wiper to V- allows ±1 mV offset adjustment. Also note that the OPA132U output swings to within approximately 1.5 V of either rail on 600 Ω loads; for true rail-to-rail output swing, consider the OPA369 or LMV321 family instead. The OPA132U is unity-gain stable, but excessive capacitive load (>1000 pF) directly at the output may cause peaking - isolate capacitive loads with a 50 Ω series resistor.
Compliance Information
RoHS and REACH compliant per TI product page. MSL Level 3 (168 hours) per PartGenie compliance notes. Not AEC-Q100 qualified - consult TI for automotive-grade op amps in this performance class.
