Instrumentation Amplifier Texas Instruments INA122UA, single-channel, SO-8 package

Texas Instruments INA122UA is a single-channel instrumentation amplifier in an SO-8 package designed to amplify small differential voltages with precision and low noise. It is intended for sensor interfacing and signal conditioning in applications that require accurate amplification of low-level signals from bridge transducers, strain gauges, thermocouples and other differential sources. The device integrates input protection and a stable, high common-mode rejection to simplify measurement designs and improve data acquisition accuracy.

Advantages

The INA122UA offers low input noise and high input impedance, which reduces loading on sensors and preserves signal integrity. Its single-channel configuration and compact SO-8 package allow straightforward integration on mixed-signal PCBs. The amplifier provides adjustable gain via an external resistor, enabling flexible scaling for different sensor sensitivities while maintaining stable offset and gain characteristics over common operating conditions.

Suitable for

• Amplifying low-level differential signals from strain gauges and load cells
• Conditioning thermocouple or RTD signals prior to ADC conversion
• Sensor interface circuits in medical and industrial measurement systems
• Precision data acquisition front-end stages and portable instrumentation

Key specifications

• Single-channel instrumentation amplifier topology
• SO-8 small-outline integrated circuit package
• Low input noise suitable for microvolt-level signals
• High input impedance to minimize sensor loading
• Adjustable gain via external resistor for flexible amplification
• High common-mode rejection ratio for accurate differential measurements
• Rail-to-rail compatible input range depending on supply configuration

How to use

Place the INA122UA on the PCB with correct SO-8 orientation and route differential sensor lines to the amplifier inputs, keeping traces short and balanced. Configure the desired gain by selecting an appropriate external resistor between the amplifier’s gain pins according to the device’s gain equation in the datasheet. Provide a stable supply voltage within the recommended range and include proper decoupling close to the device. After assembly, verify offset and gain with a known differential input and adjust layout or shielding if necessary to reduce noise pickup.

Recommendations

For optimal performance, use a short, star-ground layout and place bypass capacitors near the supply pins to minimize supply noise. Match input trace lengths and use ground planes to improve common-mode rejection. Choose the gain resistor with appropriate tolerance and temperature coefficient to maintain accuracy over temperature variations.