OPA121KUG4

## General Description

The Texas Instruments OPA121KUG4 is a precision, low-noise, low-offset operational amplifier optimized for high-accuracy signal conditioning and analog processing applications. It is designed for systems requiring minimal input bias current, high open-loop gain, and excellent thermal stability. The device is ideal for instrumentation, sensor interfaces, active filters, and high-resolution data acquisition systems where precision and low distortion are critical.

## Core Features

* Device Type: Precision Operational Amplifier (Op-Amp)
* Architecture: Bipolar input for low offset and low bias current
* Input Offset Voltage (V_OS): 25 µV maximum
* Input Bias Current (I_B): 1 nA typical
* Input Voltage Noise Density: 4.5 nV/√Hz at 1 kHz
* Supply Voltage Range: ±4 V to ±18 V
* Common-Mode Voltage Range: Rail-to-rail input not supported; typical CM range is V- + 2 V to V+ - 2 V
* Slew Rate: 3 V/µs typical
* Gain-Bandwidth Product: 8 MHz typical
* Low Total Harmonic Distortion (THD): 0.0005% typical at 1 kHz

## Electrical Specifications

* Supply Current (I_CC): 1.8 mA typical at ±15 V
* Input Offset Voltage Temperature Coefficient: 0.3 µV/°C
* Input Resistance (R_IN): 10 GΩ typical
* Output Voltage Swing: ±13.5 V typical on ±15 V supply with 2 kΩ load
* Open-Loop Gain (A_OL): 120 dB typical at ±15 V supply
* CMRR (Common-Mode Rejection Ratio): 120 dB typical
* PSRR (Power Supply Rejection Ratio): 120 dB typical
* Output Short-Circuit Current: ±25 mA typical
* Load Drive Capability: ±10 mA into 2 kΩ load

## Timing and Dynamic Characteristics

* Slew Rate (SR): 3 V/µs typical
* Settling Time to 0.01%: 5 µs typical for 10 V step
* Unity Gain Crossover Frequency: 8 MHz typical
* Phase Margin: 65° typical, ensuring stability in most closed-loop configurations
* Noise: Low input voltage and current noise suitable for high-resolution applications

## Thermal and Reliability

* Operating Temperature Range: -40°C to +85°C
* Storage Temperature Range: -65°C to +150°C
* Junction-to-Ambient Thermal Resistance (R_thJA): 150°C/W typical for UQFN package
* Package Type: 14-pin UQFN (4 mm × 4 mm) with excellent thermal and space efficiency
* RoHS Compliant, Lead-Free

## Applications

* Precision instrumentation amplifiers and sensor interfaces
* Active filtering, including low-pass, high-pass, and band-pass filters
* High-resolution ADC front-end circuits
* Medical instrumentation and ECG/EEG signal processing
* Data acquisition and laboratory measurement systems
* Audio preamplifiers requiring ultra-low distortion and low noise
* Industrial process control and analog signal conditioning

## Performance Characteristics

* Ultra-low input offset voltage and bias current provide high-accuracy operation in DC-coupled and low-frequency applications
* Low input voltage noise and THD enable high-fidelity analog signal processing
* High open-loop gain and excellent CMRR ensure precise differential measurement and amplification
* Wide supply voltage range allows flexible operation in single- or dual-supply systems
* Fast settling time and moderate slew rate balance speed and stability for high-precision applications
* UQFN package enables compact PCB layout with reduced parasitic inductance and enhanced thermal dissipation
* Excellent thermal stability supports consistent operation across industrial temperature ranges

The Texas Instruments OPA121KUG4 is a high-performance precision operational amplifier designed for applications demanding low offset, low noise, and high linearity. Its combination of low input bias current, high open-loop gain, excellent CMRR/PSRR, and robust thermal characteristics makes it suitable for precision analog signal conditioning, instrumentation, and high-resolution measurement systems.