SBOS826D December 2017 – October 2019 OPA207
The electromagnetic interference (EMI) rejection ratio, or EMIRR, describes the EMI immunity of operational amplifiers. An adverse effect that is common to many operational amplifiers is a change in the offset voltage as a result of RF signal rectification. An operational amplifier that is more efficient at rejecting this change in offset as a result of EMI has a higher EMIRR and is quantified by a decibel value. Measuring EMIRR can be performed in many ways, but this report provides the EMIRR IN+, which specifically describes the EMIRR performance when the RF signal is applied to the noninverting input pin of the operational amplifier. In general, only the noninverting input is tested for EMIRR for the following three reasons:
If available, any dual and quad operational amplifier device versions have nearly similar EMIRR IN+ performance. The OPA207 unity-gain bandwidth is 1 MHz. EMIRR performance below this frequency denotes interfering signals that fall within the operational amplifier bandwidth.
Table 1 shows the EMIRR IN+ values for the OPA207 at particular frequencies commonly encountered in real-world applications. Applications listed in Table 1 may be centered on or operated near the particular frequency shown. This information may be of special interest to designers working with these types of applications, or working in other fields likely to encounter RF interference from broad sources, such as the industrial, scientific, and medical (ISM) radio band.
|400 MHz||Mobile radio, mobile satellite/space operation, weather, radar, UHF||72 dB|
|900 MHz||GSM, radio com/nav./GPS (to 1.6 GHz), ISM, aeronautical mobile, UHF||83 dB|
|1.8 GHz||GSM, mobile personal comm. broadband, satellite, L-band||95 dB|
|2.4 GHz||802.11b/g/n, Bluetooth®, mobile personal comm., ISM, amateur radio/satellite, S-band||94 dB|
|3.6 GHz||Radiolocation, aero comm./nav., satellite, mobile, S-band||103 dB|
|5 GHz||802.11a/n, aero comm./nav., mobile comm., space/satellite operation, C-band||102 dB|