Agilent Technologies HP 8719D Service Manual page 346

Signal Separation
Figure 12-5. Signal Separation, Simplified Block Diagram
The M/A/D/S microcircuit accomplishes four separate functions:
The modulator controls the output power proportionally to the signal produced
by the ALC circuit on the source Interface board.
The amplifier provides up to + 30 dB of amplification that will allow up to + 5
be
output from the test port.
The detector outputs a voltage that is proportional to the RF power out of the
by
amplifier. This voltage is used the ALC circuit on the source Interface board.
The power source divides the source signal into two parts. One signal is routed
directly to the A64 R sampler and the other is sent through the A69 step
attenuator, S4 transfer switch, A60 and A61 bias tees, A62/A63 directional
the test
couplers and to ports.
The M/A/D/S microcircuit is controlled by the ALC circuitry on the source
interface board. The CPU provides fine control of the test port power for
applications such as power sweep.
Theory of Operation