OA1ZHA Datasheet, PDF (22/35 Pages) STMicroelectronics – Fitness and healthcare

Application information
OA1ZHA, OA2ZHA, OA4ZHA
5.9
5.10
Optimized application recommendation
OA1ZHA, OA2ZHA and OA4ZHA CMOS op amp are based on chopper architecture. As
they are switched devices, it is strongly recommended to place a 0.1 µF capacitor as close
as possible to the supply pins.
A good decoupling has several advantages for an application. First, it helps to reduce
electromagnetic interference. Due to the modulation of the chopper, the decoupling
capacitance also helps to reject the small ripple that may appear on the output.
OA1ZHA, OA2ZHA and OA4ZHA CMOS op amp have been optimized for use with 10 kΩ
in the feedback loop. With this, or a higher value of resistance, these devices offer the best
performance.
EMI rejection ration (EMIRR)
The electromagnetic interference (EMI) rejection ratio, or EMIRR, describes the EMI
immunity of operational amplifiers. An adverse effect that is common to many op amp is a
change in the offset voltage as a result of RF signal rectification.
OA1ZHA, OA2ZHA and OA4ZHA CMOS op amp have been specially designed to minimize
susceptibility to EMIRR and show an extremely good sensitivity. Figure 46: "EMIRR on IN+
pin" shows the EMIRR IN+ of the OA1ZHA, OA2ZHA and OA4ZHA measured from 10 MHz
up to 2.4 GHz.
Figure 46: EMIRR on IN+ pin
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