This, it continues, allows the device to maintain high precision across the entire input range in such applications as test and measurement, medical and safety equipment and high-resolution data-acquisition systems. Ying Zhou, marketing manager for precision amplifiers, said: “Op amps have to deal with different sensors, such as temperature and pressure, so need high precision. They also need low noise and existing products either have too much noise or not enough bandwidth.”
The OPA388’s architecture offers high input linearity and precision. Zero drift eliminates temperature drift and flicker noise, while the zero-crossover topology eliminates offset errors caused by common-mode limitations.
Zhou pointed out: “The architecture minimises 1/f noise. With some amps, this can be 100nV/√Hz; this device is less than 10nV/√Hz over frequencies ranging from 1 to 10kHz, so it’s good for small sensor signals.”
Zero crossover functionality is enabled by an internal 1.8V charge pump. “Traditionally, zero crossover is implemented using P and N channel devices to get rail to rail operation. However, in the transition between the two, the voltage might jump or change quickly,” Zhou explained. “The charge pump gives a linear output with almost no harmonics.”
With a 10MHz gain bandwidth product, the part has a total harmonic distortion of -132dBc and an open loop gain of 148dB.
