Cross-Coupled LC Oscillator

325

08:19:31

This circuit is a different version of LC based oscillator. It oscillates at 1Ghz and it has 2*Vdd amplitude. Cgs and Cgd capacitances of the mosfets are used for obtaining LC Tank. Enjoy!


!!!  IMPORTANT  !!!

In order to see oscillation

--Change first switch and wait for a while. 
After that, change the second switch.
The later the second switch is closed, the faster the system becomes stable.
--Do not increase the speed of simulation time above 1ns !
Everycircuit increases the step size if the simulation time becomes longer. In other words, It skips details. The system oscillates around 1Ghz frequency. If you increase the simulation speed above 1ns, the oscillation will disappear. If you want to decrease the speed of simulation time, it does not matter because the smaller step size is the more real.

published 9 years ago

slodpicker

9 years ago

Interesting, Imaginative, have you built it? Will try it myself soon.

asdasda

9 years ago

For detailed analysis, you can check these sources: "Ultra-Low-Voltage High-Performance CMOS VCOs Using Transformer Feedback,Kwok,Luong,2005" "A High-Performance CMOS Voltage-Controlled Oscillator for Ultra-Low-Voltage Operations,Hsieh,Lu,2007"

asdasda

9 years ago

It is also mentioned here: http://www.sciencedirect.com/science/article/pii/S0026269216306097

asdasda

9 years ago

Main idea is using inverters and LC tank circuit together. If you ignore the series resistance comes from inductor, oscillation frequency is 1/(2*pi*sqrt(L*C)). Capacitance comes from parasitic capacitances of Mosfets, Cin = (W*L*Co).

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