Our goal is going to be to find the pole(s) of the circuit.
Okay? What is a pole and why do I care where it is?
A pole is a frequency at which the gain of the device rolls off. (remember that when it rolls off , it will be at the -3dB frequency with a slope of -20dB/decade)
1. Take a look at one of the circuits and see what you notice, how about the MOSFET. This step is just to help us with our knowledge understanding of the circuit.
- At a glance it just looks just like another MOSFET right? Sure is, but let's take a look at a few things just for kicks. Notice that it is using a bypass capacitor at the source so we don't have to worry about (at when working with high frequency). Since the capacitor bypasses to ground, you should notice that this is a common-source amplifier. You could notice the Values for and and start to think about what the Gate voltage is and how that may affect the circuit.
2. We are talking about frequency response so that means we are probably going to want to draw the small signal equivalent circuit.
Remember that the capacitors and will act like short circuits at high frequencies so we will ignore them, but we will have to account for some of the capacitance internal to the device.