A5 Sig Gen Synth - Agilent Technologies 8648A Operation And Service Manual

Theory of Operation

A5 Sig Gen Synth

A5 Sig Gen Synth
The synthesizer assembly uses a 200 kHz reference signal from the A4 reference assembly
and generates a 500 to 1000 MHz signal using a divide-by-n phase-locked loop VCO.
Frequency and phase modulation are also done in the synthesizer assembly. The
frequency is modulated both inside and outside of the loop bandwidth. FM outside of the
loop bandwidth is summed with the integrator error voltage and applied directly to the
VCO. FM within the loop bandwidth and phase modulation signals are applied to a phase
modulator along with the signal from the divide-by-n circuitry and then applied to the
phase detector.
The synthesizer assembly contains a calibration ROM that contains factory-generated
calibration data that is specific to the assembly.
5a-10