Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
M1 and M2 are the main differential amplifier. Its output is amplified by the second differential pair M3 and M4. Its output is taken from M4, through two Emitter followers M10 and M11 and fed back to the two differential inputs of the main differential amplifier M1 and M2.
If you follow the polarity of the feedback you will find that the feedback to M1 input is positive feedback, and the feedback to M2 input is negative feedback.
The crystal shorts to ground the negative feedback at M2 input only at its series resonance, so the net feedback left is positive, and if its magnitude is large enough, the circuit will oscillate.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
