The PLL (phase lock loop) is realized by form of charge pump, its loop filter is passive two-order LPF. Compared to other form of active filter, this CP PLL has less noise, which does some good to its output spectrum.

• 微波锁相环采用电荷泵的形式,其环路滤波器为无源二阶低通滤波器,相比采用有源滤波器的锁相环,它不会附加有源噪声,而且滤波器结构简单,便于调试。