AR 10051217, Operating And Service Manual

Page: 75 / 90

Rev A 51
3. THEORY OF OPERATION
3.1 INTRODUCTION
The Model 2000S1G2z8 RF amplifier consists of a 1–2.8 GHz RF amplifier assembly. The RF amplifier
assembly consists of a Pre-Amplifier (Pre-Amp), one (1) high power Quadrature-Coupled Amplifier (Quad
Amp) used as a driver, (1) 2-Way Splitter, (2) high power Quad amps, (2) 4-way Splitters, (8) additional high
power Quad amps, (8) additional 4-Way Splitters , (32) high power Quad amp finals, (4) 8-way Combiners (1)
4-Way Combiner and Directional Coupler assembly. Reference Block Diag. 10051361 for breakdown of RF
structure.
The power supply section consists of an AC input, circuit breaker, filter, nine switching power supplies, and
two regulator circuits.
The control system consists of a Control/Fault Board, an Interface Board and remote interfaces for IEEE-488,
RS-232, USB, and Ethernet.
Global fault monitoring and reporting is controlled through the front panel display.
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.