Table 7-1 lists the EMIRR IN+ values for the OPA165x 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.

Table 7-1. OPA165x EMIRR IN+ for Frequencies of Interest

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

7.3.3.1 EMIRR IN+ Test Configuration

Figure 7-4 shows the circuit configuration for testing the EMIRR IN+. An RF source is connected to the

operational amplifier noninverting input pin using a transmission line. The operational amplifier is configured

in a unity-gain buffer topology with the output connected to a low-pass filter (LPF) and a digital multimeter

(DMM). A large impedance mismatch at the operational amplifier input causes a voltage reflection; however, this

effect is characterized and accounted for when determining the EMIRR IN+. The resulting dc offset voltage is

sampled and measured by the multimeter. The LPF isolates the multimeter from residual RF signals that can

interfere with multimeter accuracy. See the EMI Rejection Ratio of Operational Amplifiers application report for

more details.

+

±

Low-Pass Filter

50

Digital Multimeter

Ambient temperature: 25Û&

Sample /

Averaging

+VS

-VS

Not shown: 0.1 µF and 10 µF

supply decoupling

RF source

DC Bias: 0 V

Modulation: None (CW)

Frequency Sweep: 201 pt. Log

Figure 7-4. EMIRR IN+ Test Configuration Schematic

7.4 Device Functional Modes

The OPA165x have a single functional mode and are operational when the power-supply voltage is greater than

4.5 V. The maximum specified power-supply voltage for the OPA165x is 36 V.

In all cases, the common-mode voltage must be maintained within the specified range. In addition, key

parameters are specified over the temperature range of TA = –40°C to +125°C.

OPA1655, OPA1656

SBOS901C – MARCH 2019 – REVISED SEPTEMBER 2022

www.ti.com

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