A low phase noise frequency multiplier.

摘要

A low phase noise frequency multiplier is disclosed for multiplying a sine wave obtained from a low phase noise crystal oscillator to higher frequencies than can be directly obtained from a crystal oscillator. The multiplication occurs without the ordinary increase in phase noise. The multiplier, when tripling the frequency contains a low phase noise frequency doubler (21). The double and triple frequency terms in the tripler are synthesized from two orthogonally related derivatives of the same wave, which are then multiplied in a double balanced mixer (22). The process reinforces the desired harmonics while not reinforcing the short term random phase noise, and produces a substantial improvement in the single sideband phase noise ratio over conventional frequency multipliers. <IMAGE>