I-phase modulator iyisekethe lapho isigaba segagasi lomthwali silawulwa khona yisignali yokuguqula. Kunezinhlobo ezimbili zokuguqulwa kwesigaba se-sine wave: ukuguqulwa kwesigaba esiqondile kanye nokuguqulwa kwesigaba esingaqondile. Umgomo wokuguqulwa kwesigaba esiqondile ukusebenzisa isignali yokuguqula ukushintsha ngqo amapharamitha e-resonant loop, ukuze isignali yomthwali nge-resonant loop ikhiqize ukushintsha kwesigaba bese yakhe igagasi lokuguquguquka kwesigaba; Indlela yokuguqulwa kwesigaba esingaqondile kuqala iguqula ubukhulu begagasi eliguquliwe, bese iguqula ushintsho lwe-amplitude lube ushintsho lwesigaba, ukuze kufezwe ukuguqulwa kwesigaba. Le ndlela yadalwa ngu-Armstrong ngo-1933, ebizwa ngokuthi indlela yokuguqula i-Armstrong
I-microwave phase shifter elawulwa ngogesi iyinethiwekhi enamachweba amabili esetshenziselwa ukunikeza umehluko wesigaba phakathi kwezimpawu zokukhipha nezokufaka ezingalawulwa yisignali yokulawula (ngokuvamile i-DC bias voltage). Inani le-phase shift lingahluka ngokuqhubekayo ngesignali yokulawula noma ngenani elinqunyiwe elinqunyiwe. Zibizwa ngokuthi ama-analog phase shifters kanye nama-digital phase shifters ngokulandelana. I-phase modulator iyi-binary phase shift keying modulator ohlelweni lokuxhumana lwe-microwave, olusebenzisa i-continuous square wave ukulinganisa isignali yesithwali. I-Sine wave phase modulation ingahlukaniswa ibe yi-direct phase modulation kanye ne-indirect phase modulation. Ngokusebenzisa ubudlelwano bokuthi i-sine wave amplitude I-Angle iyingxenye yemvamisa esheshayo, i-frequency modulated wave ingaguqulwa ibe yi-phase modulated wave (noma ngokuphambene nalokho). I-direct phase modulator circuit esetshenziswa kakhulu yi-varactor diode phase modulation modulation circuit. I-indirect phase modulation circuit iyinkimbinkimbi kakhulu kune-direct phase modulation circuit. Isimiso sayo ukuthi umzila owodwa wesignali yesithwali ushintshwa yi-90° phase shifter bese ungena kwi-balanced amplitude-modulator ukucindezela i-amplitude modulation yesithwali. Ngemva kokunciphisa kahle, isignali etholakele ingezwa kwenye indlela yesithwali ukuze kukhishwe isignali yokulawula i-amplitude. Le circuit ibonakala ngokuqina kwemvamisa ephezulu, kodwa ukushintsha kwesigaba akukwazi ukuba kukhulu kakhulu (ngokuvamile ngaphansi kuka-15°) noma ukuphambuka okukhulu. I-modulator yesigaba esilula ivame ukusetshenziswa kuma-transmitter okusakaza i-FM.
