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Precision op amps (Vos<1mV)

OPA325

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Low noise (10nV/rtHz), wide bandwidth (10MHz), low power (0.65mA), zero crossover op amp

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Data sheet

OPA325

ACTIVE
Data sheet Order now

Product details

Number of channels (#) 1 Total supply voltage (Max) (+5V=5, +/-5V=10) 5.5 Total supply voltage (Min) (+5V=5, +/-5V=10) 2.2 Vos (offset voltage @ 25 C) (Max) (mV) 0.15 GBW (Typ) (MHz) 10 Features Zero Crossover Slew rate (Typ) (V/us) 5 Rail-to-rail In, Out Offset drift (Typ) (uV/C) 2 Iq per channel (Typ) (mA) 0.65 Vn at 1 kHz (Typ) (nV/rtHz) 10 CMRR (Typ) (dB) 114 Rating Catalog Operating temperature range (C) -40 to 125 Input bias current (Max) (pA) 10 Output current (Typ) (mA) 30 Architecture CMOS THD + N @ 1 kHz (Typ) (%) 0.0005
Number of channels (#) 1 Total supply voltage (Max) (+5V=5, +/-5V=10) 5.5 Total supply voltage (Min) (+5V=5, +/-5V=10) 2.2 Vos (offset voltage @ 25 C) (Max) (mV) 0.15 GBW (Typ) (MHz) 10 Features Zero Crossover Slew rate (Typ) (V/us) 5 Rail-to-rail In, Out Offset drift (Typ) (uV/C) 2 Iq per channel (Typ) (mA) 0.65 Vn at 1 kHz (Typ) (nV/rtHz) 10 CMRR (Typ) (dB) 114 Rating Catalog Operating temperature range (C) -40 to 125 Input bias current (Max) (pA) 10 Output current (Typ) (mA) 30 Architecture CMOS THD + N @ 1 kHz (Typ) (%) 0.0005
SOT-23 (DBV) 5 5 mm² 2.9 x 1.6
  • Precision with zero-crossover distortion:
    • Low offset voltage: 150 µV (maximum)
    • High CMRR: 114 dB
    • Rail-to-rail I/O
  • Wide bandwidth: 10 MHz
  • Quiescent current: 650 µA/ch
  • Single-supply voltage range: 2.2 V to 5.5 V
  • Low input bias current: 0.2 pA
  • Low noise: 9 nV/√Hz at 10 kHz
  • Slew rate: 5 V/µs
  • Unity-gain stable
  • Precision with zero-crossover distortion:
    • Low offset voltage: 150 µV (maximum)
    • High CMRR: 114 dB
    • Rail-to-rail I/O
  • Wide bandwidth: 10 MHz
  • Quiescent current: 650 µA/ch
  • Single-supply voltage range: 2.2 V to 5.5 V
  • Low input bias current: 0.2 pA
  • Low noise: 9 nV/√Hz at 10 kHz
  • Slew rate: 5 V/µs
  • Unity-gain stable

The OPA325, OPA2325, and OPA4325 (OPAx325) are precision, low-voltage complementary metal-oxide semiconductor (CMOS) operational amplifiers optimized for very low noise and wide bandwidth, while operating on a low quiescent current of only 650 µA.

The OPAx325 feature a linear input stage with zero-crossover distortion that delivers excellent common-mode rejection ratio (CMRR) of typically 114 dB over the entire input range. The input common-mode range extends 100 mV beyond the negative and positive supply rails. The output voltage typically swings within 10 mV of the rails.

The zero-crossover distortion, combined with wide bandwidth (10 MHz), high slew rate (5 V/µs), and low noise (9 nV/√Hz), make the OPAx325 a very good successive-approximation register (SAR) analog-to-digital converter (ADC) input driver amplifier. In addition, the OPAx325 have a wide supply-voltage range from 2.2 V to 5.5 V, with excellent power-supply rejection ratio (PSRR) over the entire supply range, making the device an excellent choice for precision, low-power applications that run directly from batteries without regulation.

The OPA325 (single-channel version) is available in the SOT23-5 package. The OPA2325 (dual-channel version) is offered in SO-8 and MSOP-8 packages. The OPA4325 (quad-channel version) is available in TSSOP-14 package.

The OPA325, OPA2325, and OPA4325 (OPAx325) are precision, low-voltage complementary metal-oxide semiconductor (CMOS) operational amplifiers optimized for very low noise and wide bandwidth, while operating on a low quiescent current of only 650 µA.

The OPAx325 feature a linear input stage with zero-crossover distortion that delivers excellent common-mode rejection ratio (CMRR) of typically 114 dB over the entire input range. The input common-mode range extends 100 mV beyond the negative and positive supply rails. The output voltage typically swings within 10 mV of the rails.

The zero-crossover distortion, combined with wide bandwidth (10 MHz), high slew rate (5 V/µs), and low noise (9 nV/√Hz), make the OPAx325 a very good successive-approximation register (SAR) analog-to-digital converter (ADC) input driver amplifier. In addition, the OPAx325 have a wide supply-voltage range from 2.2 V to 5.5 V, with excellent power-supply rejection ratio (PSRR) over the entire supply range, making the device an excellent choice for precision, low-power applications that run directly from batteries without regulation.

The OPA325 (single-channel version) is available in the SOT23-5 package. The OPA2325 (dual-channel version) is offered in SO-8 and MSOP-8 packages. The OPA4325 (quad-channel version) is available in TSSOP-14 package.
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Technical documentation

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Type Title Date
* Data sheet OPAx325 Precision, 10-MHz, Low-Noise, Low-Power, RRIO, CMOS Operational Amplifiers datasheet (Rev. D) PDF | HTML 26 Jun 2019
Application note How to Select Amplifiers for Pressure Transmitter Applications (Rev. A) PDF | HTML 27 Jul 2021
Circuit design Single-supply, 2nd-order, Sallen-Key high-pass filter circuit PDF | HTML 28 Jun 2021
Circuit design Single-supply, 2nd-order, Sallen-Key low-pass filter circuit PDF | HTML 28 Jun 2021
Circuit design Single-supply, 2nd-order, multiple feedback band-pass filter circuit PDF | HTML 28 Jun 2021
Circuit design Single-supply, 2nd-order, multiple feedback high-pass filter circuit PDF | HTML 28 Jun 2021
Circuit design Single-supply, 2nd-order, multiple feedback low-pass filter circuit PDF | HTML 28 Jun 2021
Technical article “Trust, but verify” SPICE model accuracy, part 2: input offset voltage vs. input common-mode voltage 05 Sep 2017
Circuit design Single-supply, 2nd-order, Sallen-Key band-pass filter circuit PDF | HTML 29 Jun 2017

Design & development

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Evaluation board

ADS7066EVM-PDK —

ADS7066 performance demonstration kit for eight-channel, 250-kSPS, 16-bit, internal-reference ADC

The ADS7066 evaluation module (EVM) performance demonstration kit (PDK) is a platform for evaluating the performance of the ADS7066 successive approximation register (SAR) analog-to-digital converter (ADC)

The ADS7066EVM-PDK provides power and a communications card complete with a graphical user (...)

User guide: PDF
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Evaluation board

DIP-ADAPTER-EVM — DIP adapter evaluation module

Speed up your op amp prototyping and testing with the DIP-Adapter-EVM, which provides a fast, easy and inexpensive way to interface with small, surface-mount ICs. You can connect any supported op amp using the included Samtec terminal strips or wire them directly to existing circuits.

The (...)

User guide: PDF
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Evaluation board

DIYAMP-EVM — Universal Do-It-Yourself (DIY) Amplifier Circuit Evaluation Module

The DIYAMP-EVM is a unique evaluation module (EVM) family that provides engineers and do it yourselfers (DIYers) with real-world amplifier circuits, enabling you to quickly evaluate design concepts and verify simulations. It is available in three industry-standard packages (SC70, SOT23, SOIC) and (...)
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Support software

Simulation File for Single-supply, Second-order, MFB Band-pass Filter Circuit

SBOC596.TSC (85 KB)
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Support software

Simulation file for Low-Pass MFB Filter Circuit

SBOC597.TSC (67 KB)
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Support software

Simulation for Single-supply, Second Order, Sallen-Key Lowpass Filter Circuit

SBOC598.TSC (61 KB)
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Support software

Simulation for Single-supply, Second-order, Multiple-feedback High-pass Filter

SBOC599.TSC (61 KB)
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Simulation model

OPAx325 PSpice Model (Rev. C)

SBOMA82C.ZIP (29 KB) - PSpice Model
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Simulation model

OPAx325 TINA-TI Reference Design (Rev. B)

SBOMA81B.TSC (317 KB) - TINA-TI Reference Design
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Simulation model

OPAx325 TINA-TI Spice Model (Rev. B)

SBOMA80B.ZIP (10 KB) - TINA-TI Spice Model
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Calculation tool

ANALOG-ENGINEER-CALC — Analog engineer's calculator

The analog engineer’s calculator is designed to speed up many of the repetitive calculations that analog circuit design engineers use on a regular basis. This PC-based tool provides a graphical interface with a list of various common calculations ranging from setting operational-amplifier (...)
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Calculation tool

OPAMP-NOISECALC — Noise Calculator, Generator and Examples

This folder contains three tools to help in understandning and managing noise in cicuits. The included tools are:
  • A noise generator tool - This is a Lab View 4-Run Time executable that generates Gaussian white noise, uniform white noise, 1/f noise, short noise, and 60Hz line noise. Temporal data, (...)
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Design tool

CIRCUIT060001 —

Single-supply, low-side, unidirectional current-sensing circuit

This single–supply, low–side, current sensing solution accurately detects load current up to 1A and converts it to a voltage between 50mV and 4.9V. The input current range and output voltage range can be scaled as necessary and larger supplies can be used to accommodate larger swings.
User guide: PDF
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Design tool

CIRCUIT060002 — Temperature sensing with NTC thermistor circuit

This temperature sensing circuit uses a resistor in series with a negative–temperature–coefficient (NTC) thermistor to form a voltage divider, which has the effect of producing an output voltage that is linear over temperature. The circuit uses an op amp in a non–inverting (...)
User guide: PDF
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Design tool

CIRCUIT060003 — Temperature sensing with PTC thermistor circuit

This temperature sensing circuit uses a resistor in series with a positive–temperature–coefficient (PTC) thermistor to form a voltage–divider, which has the effect of producing an output voltage that is linear over temperature. The circuit uses an op amp in a non–inverting (...)
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Design tool

CIRCUIT060004 — Low-noise and long-range PIR sensor conditioner circuit

This two stage amplifier design amplifies and filters the signal from a passive infrared (PIR) sensor. The circuit includes multiple low–pass and high–pass filters to reduce noise at the output of the circuit to be able to detect motion at long distances and reduce false triggers. This (...)
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Design tool

CIRCUIT060005 — High-side current sensing with discrete difference amplifier circuit

This single–supply, high–side, low–cost current sensing solution detects load current between 50mA and 1A and converters it to an output voltage from 0.25V to 5V. High–side sensing allows for the system to identify ground shorts and does not create a ground disturbance on (...)
User guide: PDF
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Design tool

CIRCUIT060006 — Bridge amplifier circuit

A strain gauge is a sensor whose resistance varies with applied force. To measure the variation in resistance, the strain gauge is placed in a bridge configuration. This design uses a 2 op amp instrumentation circuit to amplify a differential signal created by the change in resistance of a strain (...)
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Design tool

CIRCUIT060007 — Low-side, bidirectional current-sensing circuit

This single-supply low-side, bidirectional current sensing solution can accurately detect load currents from –1A to 1A. The linear range of the output is from 110mV to 3.19V. Low-side current sensing keeps the common-mode voltage near ground, and is thus most useful in applications with (...)
User guide: PDF
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Design tool

CIRCUIT060008 — Full-wave rectifier circuit

This absolute value circuit can turn alternating current (AC) signals to single polarity signals. This circuit functions with limited distortion for ±10-V input signals at frequencies up to 50kHz and for signals as small as ±25mV at frequencies up to 1kHz.
User guide: PDF
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Design tool

CIRCUIT060009 — Half-wave rectifier circuit

The precision half-wave rectifier inverts and transfers only the negative-half input of a time varying input signal (preferably sinusoidal) to its output. By appropriately selecting the feedback resistor values, different gains can be achieved. Precision half-wave rectifiers are commonly used with (...)
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Design tool

CIRCUIT060010 — PWM generator circuit

This circuit utilizes a triangle wave generator and comparator to generate a 500 kHz pulse-width modulated (PWM) waveform with a duty cycle that is inversely proportional to the input voltage. An op amp and comparator generate a triangle waveform which is applied to the inverting input of a second (...)
User guide: PDF
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Design tool

CIRCUIT060011 — Single-supply, second-order, multiple feedback high-pass filter circuit

The multiple-feedback (MFB) high-pass (HP) filter is a 2nd-order active filter. Vref provides a DC offset to accommodate for single-supply applications. This HP filter inverts the signal (Gain = –1 V/V) for frequencies in the pass band. An MFB filter is preferable when the gain is high or (...)
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Design tool

CIRCUIT060012 — Single-supply, 2nd-order, multiple feedback low-pass filter circuit

The multiple-feedback (MFB) low-pass filter (LP filter) is a second-order active filter. Vref provides a DC offset to accommodate for single-supply applications. This LP filter inverts the signal (Gain = –1 V/V) for frequencies in the pass band. An MFB filter is preferable when the gain is (...)
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Design tool

CIRCUIT060014 — Voltage-to-current (V-I) converter circuit with MOSFET

This single-supply, low-side, V-I converter delivers a well-regulated current to a load which can be connected to a voltage greater than the op amp supply voltage. The circuit accepts an input voltage between 0 V and 2 V and converts it to a current between 0 mA and 100 mA. The current is (...)
User guide: PDF
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Design tool

CIRCUIT060016 — Non-inverting microphone pre-amplifier circuit

This circuit uses a non–inverting amplifier circuit configuration to amplify the microphone output signal. This circuit has very good magnitude flatness and exhibits minor frequency response deviations over the audio frequency range. The circuit is designed to be operated from a single 5-V (...)
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Design tool

CIRCUIT060017 — Dual-supply, discrete, programmable gain amplifier circuit

This circuit provides programmable, non-inverting gains ranging from 6 dB (2 V/V) to 60 dB (1000 V/V) using a variable input resistance. The design maintains the same cutoff frequency over the gain range.
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CIRCUIT060018 — Photodiode amplifier circuit

This circuit consists of an op amp configured as a transimpedance amplifier for amplifying the light dependent current of a photodiode.
User guide: PDF
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Design tool

CIRCUIT060019 — Inverting op amp with non-inverting positive reference voltage circuit

This design uses an inverting amplifier with a non-inverting positive reference voltage to translate an input signal of –1 V to 2 V to an output voltage of 0.05 V to 4.95 V. This circuit can be used to translate a sensor output voltage with a positive slope and negative offset to a usable (...)
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Design tool

CIRCUIT060020 — Inverting amplifier circuit

This design inverts the input signal, Vi , and applies a signal gain of –2 V/V. The input signal typically comes from a low-impedance source because the input impedance of this circuit is determined by the input resistor, R1. The common-mode voltage of an inverting amplifier is equal to the (...)
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Design tool

CIRCUIT060053 — High-pass Sallen-Key filter circuit

The Butterworth Sallen-Key (SK) high-pass (HP) filter is a 2nd-order active filter. Vref provides a DC offset to accommodate for single-supply applications. An SK filter is usually preferred when small Q factor is desired, noise rejection is prioritized and when a non-inverting gain of the filter (...)
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Design tool

CIRCUIT060054 — Low-pass Sallen-Key filter circuit

The Butterworth Sallen-Key low-pass filter is a second-order active filter. Vref provides a DC offset to accommodate for single-supply applications. A Sallen-Key filter is usually preferred when small Q factor is desired, noise rejection is prioritized and when a non-inverting gain of the filter (...)
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Design tool

CIRCUIT060055 — Multiple feedback band-pass filter circuit

This circuit is a 2nd-order multiple feedback (MFB) band-pass (BP) filter. This BP filter is created by cascading a low-pass and a high-pass filter. Vref provides a DC offset to accommodate for single-supply applications.
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Design tool

CIRCUIT060056 — Band-pass Sallen-Key filter circuit

This circuit is a single-supply, 2nd-order Sallen-Key (SK) band-pass (BP) filter. It is designed by cascading an SK low-pass filter and an SK high-pass filter. Vref provides a DC offset to accommodate for a single supply.
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Design tool

CIRCUIT060074 — High-side current sensing with comparator circuit

This high-side, current sensing solution uses one comparator with a rail-to-rail input common mode range to create an over-current alert (OC-Alert) signal at the comparator output (COMP OUT) if the load current rises above 1 A. The OC-Alert signal in this implementation is active low. So when the (...)
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Design tool

CIRCUIT060075 — High-speed overcurrent detection circuit

This high-speed, low-side overcurrent detection solution is implemented with a single zero-drift fast-settling amplifier (OPA388) and one high-speed comparator (TLV3201). This circuit is designed for applications that monitor fast current signals and overcurrent events, such as current detection in (...)
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Simulation tool

PSPICE-FOR-TI — PSpice® for TI design and simulation tool

PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
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Simulation tool

TINA-TI — SPICE-based analog simulation program

TINA-TI provides all the conventional DC, transient and frequency domain analysis of SPICE and much more. TINA has extensive post-processing capability that allows you to format results the way you want them. Virtual instruments allow you to select input waveforms and probe circuit nodes voltages (...)
User guide: PDF
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SOT-23 (DBV) 5 View options

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