TI claims first for zero-drift, zero-crossover op amp: precision & linearity

February 07, 2017 // By Graham Prophet
With precision and high input linearity in a single high-performance device, Texas Instruments says it has the first operational amplifier (op amp) to offer both zero-drift and zero-crossover technology. The OPA388 op amp maintains high precision across the entire input range for a variety of industrial applications, including test and measurement, medical and safety equipment, and high-resolution data-acquisition systems.

The architecture of the OPA388 produces a combination of ultra-high input linearity and precision. TI’s zero-drift technology eliminates temperature drift and flicker noise to attain the highest DC precision and dynamic error correction, while its zero-crossover topology eliminates offset errors caused by common-mode limitations to achieve linear output and true rail-to-rail input operation.

 

The OPA388 op amp delivers true precision with ultra-high input linearity: its zero-crossover topology eliminates the input offset transition region of traditional CMOS op amps, assuring maximum linearity and minimal distortion across the entire common-mode input range.

It provides high DC precision: zero-drift technology delivers a low maximum offset voltage of 5 µV, a typical offset voltage drift of 0.005 μV/°C and a maximum input bias current of 700 pA over the extended industrial temperature range of -40°C to 125°C. This eliminates the need for costly overtemperature calibration and increases DC precision.

The amp supports wide-bandwidth operation: with a 10-MHz gain bandwidth product (GBW), the OPA388 enables high gain configurations and makes it possible to acquire a wide range of signal types and frequencies to support equipment from precision weigh scales to heart-rate monitors.

Maintaining low distortion for high performance, the ultra-low total harmonic distortion of -132 dBc and voltage noise of 7 nV/√Hz help produce a high-resolution signal chain for specialized applications such as programmable logic controllers, precision field transmitters and motion-control equipment.

Merging zero-drift and zero-crossover technology reduces signal-chain complexity and external component count, allowing designers to minimize board space and bill of materials (BOM) cost.

 

TI offers a range of support tools for designers using the OPA388, including a reference design that demonstrates how to use the precision op amp to eliminate crossover nonlinearity in digital-to-analogue converters. The reference design uses the DAC8830 precision data converter and REF5050 voltage reference, which combine to create an accurate DC calibration system for high-precision applications used in wireless infrastructure and test and measurement.

 

The