LOW NOISE MICROWAVE FREQUENCY SYSNTHESIZER

摘要

Low noise microwave frequency synthesizer having a plurality of rapidly switchable output frequencies. Two banks of oscillators (10) (20) are selectively mixed to yield a range of output signals of low phase noise and low spurious noise. The first bank of oscillators (10) comprises low noise, highly stable oscillators of a frequency range below the desired synthesized output signal. The second bank of oscillators (20) comprises low noise, highly stable oscillators of a frequency range lower than the first bank. The signal from the second bank of oscillators is frequency multiplied (30) to a desired frequency ranged by a low multiplication factor and then mixed (41) with the signal from the first bank of oscillators. Multiplied phase noise is reduced by using a low multiplication factor. The upper sideband of the mixed signals is output as the synthesized output signal (50). Rapid switching (11) (21) between oscillators in both banks provides a frequency range of synthesized output signals which may be rapidly stepped through as desired.