A radiation hard design for oscillator circuits and circuits having differential outputs is described. The design includes connecting or otherwise coupling outputs of these circuits to a passive polyphase filter. The passive polyphase filter provides four quadrature outputs that are free of glitches...http://www.google.com.tw/patents/US7646254?utm_source=gb-gplus-share專利 US7646254 - Radiation hard oscillator and differential circuit design
