Thank you pancho_hideboo.
Let me take a humble bow for your enlightening and thought-provoking suggestions!
The circuit simulator is Spectre 7.1.1 - 32 bit, and the tech lib is 0.18um TSMC.
And I sincerely hope, the names 'VCO' and 'opamp' stay the same immaterial of Cadence or Synopsys or ADS! Kindly correct me if I'm wrong.
Thanks once again