theguardian2001
Junior Member level 3
Hi everyone! I am currently trying to implement an amplifier in Skywater130 using Xschem and NGspice. I have successfully tested my bias circuit in dc simulation for supply voltage variations with satisfying results. However, if I turn on ac simulation, the bias voltages are appeared to be zero.
I understand that running ac simulation on a circuit that does not have any ac sources might be strange. However, I have noticed that that when I was testing an amplifier with this circuitry in ac. Bias circuitry behaves exactly the same in the amplifier testbench, i.e. producing zeros. As far as I know an ac simulation runs a dc one first to find a op and start ac analysis around it. I would like to see my bias voltages constant across frequency sweep. Is there any method to do it? I would like to avoid placing dc sources in my amplifier schematic to emulate the bias circuitry. please see testbench of a bias circuitry and simulation results. Any considerations will be welcomed.
Thanks everyone in advance!
I understand that running ac simulation on a circuit that does not have any ac sources might be strange. However, I have noticed that that when I was testing an amplifier with this circuitry in ac. Bias circuitry behaves exactly the same in the amplifier testbench, i.e. producing zeros. As far as I know an ac simulation runs a dc one first to find a op and start ac analysis around it. I would like to see my bias voltages constant across frequency sweep. Is there any method to do it? I would like to avoid placing dc sources in my amplifier schematic to emulate the bias circuitry. please see testbench of a bias circuitry and simulation results. Any considerations will be welcomed.
Thanks everyone in advance!