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I am designing a LC CMOS Tail injection based Oscillator but somehow the node voltages are constantly showing errors. The circuit schematics are enter image description here

The properties of MOSFETs are as followed:

enter image description here

Node Voltages: enter image description here

I am getting weird results in which the Node Voltages are constantly shooting up to Mega-Volts range. It would be helpful if you could suggest what am I doing wrong possibly. Thanks in Advance

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  • \$\begingroup\$ Off topic, but unless you turned the text anchors to be visible on purpose (the small circles), if you press A you'll toggle them back to be invisible. \$\endgroup\$ – a concerned citizen Jul 10 '20 at 19:16
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You are using ideal tank, add a resistor in parallel with the LC tank, should work then.
Also, you have a floating node between the drains of the MOS. Split the inductor as a series combination of two 0.04nH inductors and connect the node in between to VDD/2 = 1.25V. Will definitely work then.

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  • \$\begingroup\$ Tried using the Resistors with values ranging from 100ohms to 1M ohms in parallel to the LC tank, but didn't help. \$\endgroup\$ – Aksh Chordia Jul 10 '20 at 9:53
  • \$\begingroup\$ @AkshChordia Also try a small resistor in series with the inductor. May or may not help. \$\endgroup\$ – Russell McMahon Jul 10 '20 at 10:22
  • \$\begingroup\$ @AkshChordia See edits\ \$\endgroup\$ – sarthak Jul 10 '20 at 14:16
  • \$\begingroup\$ @sarthak Thanks! Your suggestion works. By the time I also realised that I was a bit harsh using a constant current source. I tried inserting an N-MOS always in saturation for tail current injection initially but didn't help initially. Adjusting the Initial conditions and changing the LC values makes the circuit work. \$\endgroup\$ – Aksh Chordia Jul 10 '20 at 15:54

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