Time (100 s/div)

m

18 V

-18 V

37 V

PP

Sine Wave

( 18.5 V)

±

Device

V

I

V

O

160

140

120

100

80

60

40

20

0

10M

10G

Frequency (Hz)

100M

1G

OPA180, OPA2180, OPA4180

SBOS584D – NOVEMBER 2011 – REVISED MAY 2014

www.ti.com

Feature Description (continued)

8.3.2 EMI Rejection

The OPAx180 uses integrated electromagnetic interference (EMI) filtering to reduce the effects of EMI

interference from sources such as wireless communications and densely populated boards with a mix of analog

signal chain and digital components. EMI immunity can be improved with circuit design techniques; the OPAx180

benefits from these design improvements. Texas Instruments has developed the ability to accurately measure

and quantify the immunity of an operational amplifier over a broad frequency spectrum extending from 10 MHz to

6 GHz. Figure 25 shows the results of this testing on the OPAx180. Detailed information can also be found in the

application report, EMI Rejection Ratio of Operational Amplifiers (SBOA128), available for download from

www.ti.com.

Figure 25. OPAx180 EMIRR Testing

8.3.3 Phase-Reversal Protection

The OPAx180 family has an internal phase-reversal protection. Many op amps exhibit a phase reversal when the

input is driven beyond its linear common-mode range. This condition is most often encountered in noninverting

circuits when the input is driven beyond the specified common-mode voltage range, causing the output to

reverse into the opposite rail. The input of the OPAx180 prevents phase reversal with excessive common-mode

voltage. Instead, the output limits into the appropriate rail. This performance is shown in Figure 26.

Figure 26. No Phase Reversal

14

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