jaydnul
Newbie level 5
Without deriving the transfer function, what is the general method of identifying poles and zeroes of an arbitrary circuit? As I understand so far, to find a pole you short the voltage source and calculate the total resistance to ground and the total capacitance to ground. Then the time constant is 1/RC. If that is correct, I have a few more questions:
1. What is the method to calculate a zero? Because if you use the same method and short the voltage source, you will end up getting the same values for R and C as the pole.
2. Basically poles and zeroes are low pass and high pass circuits made by the capacitance in the circuit, right? Wouldn't that mean all of the phase changes are lags? How does a RHP pole or LHP zero manifest itself?
3. How do you tell if a pole or zero calculated with these methods is LHP or RHP? Or is the only way by deriving the transfer function?
4. How do you know when you need to use the resistance R to calculate the time constant 1/RC or the transistor gm to calculate the time constant gm/C? How do you know which gm to use?
Thanks a bunch!
1. What is the method to calculate a zero? Because if you use the same method and short the voltage source, you will end up getting the same values for R and C as the pole.
2. Basically poles and zeroes are low pass and high pass circuits made by the capacitance in the circuit, right? Wouldn't that mean all of the phase changes are lags? How does a RHP pole or LHP zero manifest itself?
3. How do you tell if a pole or zero calculated with these methods is LHP or RHP? Or is the only way by deriving the transfer function?
4. How do you know when you need to use the resistance R to calculate the time constant 1/RC or the transistor gm to calculate the time constant gm/C? How do you know which gm to use?
Thanks a bunch!