Frequency synthesiser with high frequency agility, low phase noise and with coherent direct synthesis

摘要

The synthesiser comprises a frequency standard controlled by a single reference oscillator at a frequency f0, a fine-step channel with one output, a coarse-step channel with two, or more generally M, outputs, a final synthesis channel CHF with three inputs supplying a control output of frequency fp, and a local oscillator output of frequency fOL offset from the value f1, where f1 is the intermediate frequency. The final synthesis channel receives at the input En of its switch C5 the fine-step frequencies, at the input E1 of its first mixer M1 N coarse-step frequencies, and at the input E2 of its second mixer M2 N other coarse-step frequencies offset by N intervals of frequency Nf0. Application to control circuits of Doppler radars, with pulse compression, with high frequency agility. IMAGE