OPA145 Datasheet, PDF (25/40 Pages) Texas Instruments – High-Precision, Low-Noise, Rail-to-Rail Output, 5.5-MHz JFET Operational Amplifiers

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OPA145, OPA2145, OPA4145
SBOS427 – JUNE 2017
Table 2 lists the EMIRR IN+ values for the OPA145 at particular frequencies commonly encountered in real-world
applications. Applications listed in Table 2 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.
FREQUENCY
400 MHz
900 MHz
1.8 GHz
2.4 GHz
3.6 GHz
5 GHz
Table 2. OPA145 EMIRR IN+ for Frequencies of Interest
APPLICATION OR ALLOCATION
Mobile radio, mobile satellite, space operation, weather, radar, ultra-high frequency (UHF)
applications
Global system for mobile communications (GSM) applications, radio communication, navigation,
GPS (to 1.6 GHz), GSM, aeronautical mobile, UHF applications
GSM applications, mobile personal communications, broadband, satellite, L-band (1 GHz to 2 GHz)
802.11b, 802.11g, 802.11n, Bluetooth^®, mobile personal communications, industrial, scientific and
medical (ISM) radio band, amateur radio and satellite, S-band (2 GHz to 4 GHz)
Radiolocation, aero communication and navigation, satellite, mobile, S-band
802.11a, 802.11n, aero communication and navigation, mobile communication, space and satellite
operation, C-band (4 GHz to 8 GHz)
EMIRR IN+
54 dB
68 dB
86 dB
107 dB
100 dB
105 dB
8.3.9 EMIRR +IN Test Configuration
Figure 44 shows the circuit configuration for testing the EMIRR IN+. An RF source is connected to the op amp
noninverting input terminal using a transmission line. The op amp 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 op amp 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 may interfere with multimeter accuracy.
Ambient temperature: 25Û&
RF source
DC Bias: 0 V
Modulation: None (CW)
Frequency Sweep: 201 pt. Log
+VS
±
50
+
-VS
Not shown: 0.1 µF and 10 µF
supply decoupling
Low-Pass Filter
Sample /
Averaging
Digital Multimeter
Figure 44. EMIRR +IN Test Configuration
8.4 Device Functional Modes
The OPAx145 has a single functional mode and is operational when the power-supply voltage is greater than 4.5
V (±2.25 V). The maximum power supply voltage for the OPAx145 is 36 V (±18 V).
Copyright © 2017, Texas Instruments Incorporated
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