衛星通訊用之鎖相低雜訊20GHz訊號已發展出來。電路架構的策略是
考量在元件可用性及低價位。訊號是從一個2.5GHz鎖相訊號源倍頻所產生
。2.5GHz鎖相訊號源包括有溫度控制式石英振盪器、高品質因子同軸共振
器式之電壓控制振盪器、頻率合成器之積體電路、預除器和主動式迴路濾
波器。而且，20GHz訊號是循序地由高電子移動率電晶體式的頻率四倍頻
器及頻率二倍頻器所產生。

A locked low phase noise 20GHz signal is developed for the
satellite communication. The strategy of the construction is on
the component availability and low cost. The signal is
multiplied from a 2.5GHz locked source. The locked loop for
2.5GHz source consists of a temperature controlled crystal
oscillator (TCXO), voltage controlled oscillator (VCO), high-Q
coaxial resonator, frequency synthesizer IC, and active loop
filter. And the 20GHz signal is obtained sequentially by
quadrupler and doubler frequency multiplier due to the
capability of HEMT transistor.