MEASUREMENT CIRCUIT, MEASUREMENT INSTRUMENT, AND VECTOR NETWORK ANALYZER

The measurement circuit includes a clock input, a frequency converter circuit, and a first signal generator circuit. The clock input is configured to receive a reference clock signal. The first signal generator circuit includes a first clock generator circuit configured to generate a first clock signal having an adaptable frequency based on the reference clock signal. The first signal generator circuit further includes a first direct digital synthesizer (DDS) circuit configured to generate a local oscillator (LO) signal based on the first clock signal and based on an adaptable frequency tuning word (FTW) of the first DDS circuit. The adaptable frequency of the first clock signal and the adaptable FTW of the first DDS circuit are configured such that an IF signal is free of spurs emitted by the first DDS circuit at least in a predetermined frequency band.