Method and apparatus for extending the lower frequency operation of a sampler based VNA

Abstract

Circuitry is provided to drive a step recovery diode (SRD) (8) in a sampler based vector network analyzer (VNA) that allows harmonic samplers (10, 11) to operate over many octaves. The circuit includes a digital pulse generator (FIG. 5) for providing a LO signal. The LO signal is provided over an octave frequency range as in previous SRD driver circuits, but pulse forming circuitry is provided to decrease the pulse rate to a sub multiple of the LO generating oscillator signal. The pulse forming circuitry includes a programmable frequency divider (50) to vary the pulse rate. The pulse forming network further includes registers (50, 52) connected to the programmable frequency divider (50) to limit the pulse width resulting in reduced heating of the SRDs. With an effectively wider frequency operation range using the SRD (8), only one downconversion is required in the VNA, eliminating the need for additional mixers (30, 31) and a second LO signal generator (24) to provide a second downconversion.

Dependencies are inferred from the claim text.