RF2138PCBA datasheet(9/10 Pages) RFMD

9 / 10 page

2-127

RF2138

Rev A9 011031

Typical Test Setup

Power Supply

V- S- S+ V+

10dB/5W

3dB

RF Generator

Spectrum

Analyzer

Buffer

x1 OpAmp

Puls

Generator

A buffer amplifier is recommended because the current into

the Vapc changes with voltage. As an alternative, the

voltage may be monitored with an oscilloscope.

Notes about testing the RF2138

The test setup shown above includes two attenuators. The 3dB pad at the input is to minimize the effects that the

switching of the input impedance of the PA has on the signal generator. When Vapc is switched quickly, the resulting

input impedance change can cause the signal generator to vary its output signal, either in output level or in frequency.

Instead of an attenuator an isolator may also be used. The attenuator at the output is to prevent damage to the spec-

trum analyzer, and should be able to handle the power.

It is important not to exceed the rated supply current and output power. When testing the device at higher than nominal

supply voltage, the VAPC should be adjusted to avoid the output power exceeding +36dBm. During load-pull testing at

the output it is important to monitor the forward power through a directional coupler. The forward power should not

exceed +36dBm, and VAPC needs to be adjusted accordingly. This simulates the behavior for the power control loop in

this respect. To avoid damage, it is recommended to set the power supply to limiting the current during the burst, not to

exceed the maximum current rating.

RF2138PCBA Scheda tecnica(PDF) 9 Page - RF Micro Devices