JAJSCZ4E January 2017 – December 2022 OPA1677 , OPA1678 , OPA1679
PRODUCTION DATA
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 document 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:
A more formal discussion of the EMIRR IN+ definition and test method is shown in the EMI Rejection Ratio of Operational Amplifiers application report, available for download at www.ti.com.
The EMIRR IN+ of the OPA167x is plotted versus frequency in Figure 7-3. The dual and quad operational amplifier device versions have approximately identical EMIRR IN+ performance. The OPA167x unity-gain bandwidth is 16 MHz. EMIRR performance below this frequency denotes interfering signals that fall within the operational amplifier bandwidth.
Table 7-1 lists the EMIRR IN+ values for the OPA167x at particular frequencies commonly encountered in real-world applications. Applications listed in Table 7-1 can be centered on or operated near the particular frequency shown. This information can 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.
FREQUENCY | APPLICATION OR ALLOCATION | EMIRR IN+ |
---|---|---|
400 MHz | Mobile radio, mobile satellite, space operation, weather, radar, UHF | 36 dB |
900 MHz | GSM, radio communication and navigation, GPS (to 1.6 GHz), ISM, aeronautical mobile, UHF | 42 dB |
1.8 GHz | GSM, mobile personal comm. broadband, satellite, L-band | 52 dB |
2.4 GHz | 802.11b/g/n, Bluetooth™, mobile personal comm., ISM, amateur radio and satellite, S-band | 64 dB |
3.6 GHz | Radiolocation, aero comm./nav., satellite, mobile, S-band | 67 dB |
5 GHz | 802.11a/n, aero communication and navigation, mobile communication, space and satellite operation, C-band | 77 dB |