Hi,
I am a new guy and learning to use Virtuoso ADE to optimize my amplifier design. I start from a quite simple amplifier design, which is just a diff pair, as the following figure shows.
Figure 1. Simple amplifier
An basic optimization config and local / global optimization has been completed, which includes MOSFET region (should be saturation), DC Gain > 60dB, and GBW > 5MHz.
(By the way, Q1 where is the help file of the Spec - tol 2 1, which some guidance told me tol 2 1 means saturation region. Does it belong to PDK? Or belong to Virtuoso?)
And ADE XL gives me the good final result.
Moreover, now I would like to add more specification for my amplifier, which are CMRR, PSRR, etc. Questions are here.
Let's take CMRR as an example.
Normally, we change the input voltage source V2 with AC=1, and delete V3 and V4, or set AC=0 for V3 and V4.
Then, run an AC analysis, the AC result should be A_CM, use A_DM / A_CM, we know the CMRR. (Q2: Is it a good practice?)
However, if I want to optimize CMRR for this amplifier, I will change V2, V3 and V4, the optimization may break other parameters (Like DC Gain) and may be meaningless.
Could you give me some suggestions to optimizing these performances via ADE of this amplifier?