Re: Questions about phase in .AC LTspice Analysis
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Hello Andy, Your thinking is what I see in "2stages_2CascodeDiff_ACsim_test1.jpg". Andy: I think the main reason is that those two bias sources have a large AC
component (10 times the magnitude of the actual input signal). ?Why do
you have input signals (AC components) entering through three different
places into your amplifier circuit? ?I would think that should not be
happening, which makes me believe your .AC simulation is not simulating
the circuit you think it is.
Do you mean 2 bias sources: Vcmfb1_2C_V & Vcmfb2_2C_V? let me explain what problem I have. These Vcmfb1_2C_V & Vcmfb2_2C_V are actually come from CMFB-Circuits (Common mode Feedback with switch capacitors, clocks) which adjust the common mode of outputs to Vdd/2: (Vodm+Vodp)/2 = Vdd/2 and (Vop+Vom)/2 = Vdd/2. Since the CMFB-Circuits only work in TRAN-Analysis, so I get these values Vcmfb1_2C_V & Vcmfb2_2C_V from TRAN-Analysis. So I use these 2 values for AC-Analysis. I didn't specify AC components for these 2 voltage sources, so I thought it should be alright. What should I do now?
I see something wrong with my biasing!!
Regards
Hnguyen
On Friday, December 6, 2013 7:29 AM, Andy wrote:
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