AR 60S1G6, Operating And Service Manual

Page: 31 / 46

Rev C 15
3. THEORY OF OPERATION
3.1 INTRODUCTION
The Model 60S1G6 RF amplifier consists of a 0.7–6 GHz RF amplifier assembly. The RF amplifier
assembly consists of a Pre-Amplifier (Pre-Amp), one (1) Quadrature-Coupled Amplifier (Quad Amp) used as
a driver and four (4) Quad Amps used as final amplifier stages.
The power supply section consists of an AC input filter with fuses and a switch, a switching power supply,
and a regulator circuit.
The control system consists of a Control/Fault Board, an Interface Board and remote interfaces for IEEE-488,
RS-232, USB, and Ethernet.
3.2 RF AMPLIFIER OPERATION
3.2.1 A1 Pre-Amp
The Pre-Amp is assembled on PTFE composite printed wiring boards. The RF input signal is fed to the A1
Pre-Amp. The pre-amp consists of a GaAs Attenuator, MMICs and a Wilkinson splitter. The attenuator is
used for manual gain control using the front panel gain control and to attenuate RF input signals above 0
dBm by utilizing internal voltages.
U2 is a broadband GaAs Monolithic Microwave Integrated Circuit (MMIC) and is the first stage of gain in
the amplifier. The output of U2 is fed to the input of the Wilkinson Two-Way Splitter.
The Wilkinson Two-Way Splitter splits the signal into two paths. One output is fed to the input of the A3
Driver Amp and the other output is fed to a detector. The detector output is used to protect the unit in the
event of input overdrive.
The output driver is fed to another MMIC to boost the gain. Total gain is about 30dB.