Micro Elctronic Circuits

All amplifiers typically exhibit a band-pass frequency response as in Figure 1. The cut-off frequency on the low end is usually determined by the coupling and bypass capacitors (if there are no such capacitors the low end extends all of the way to DC). The high frequency limit is typically determined by internal capacitances in the transistor itself. Low frequency response If an amplifier does not have coupling or bypass capacitors, then in general the low frequency response goes all of the way down to DC. However, as we discussed in class, it is desirable to have these capacitors in the circuit to isolate the amplifiers DC bias point from the outside world. In the most general case (Figure 2), the input and output coupling capacitors lead to a high-pass filter response determined by the resistances they see: Where R i is the source resistance, R L is the load resistance, R in is the input resistance for your amplifier and R o is the output resistance