9.115 Figure P9.115 shows a three-stage amplifier in which the stages are directly coupled. The amplifier, however, utilizes bypass capacitors, and, as such, its frequency response falls off at low frequencies. For our purposes here, we shall assume that the capacitors are large enough to act as perfect short circuits at all signal frequencies of interest.
(a) Find the dc bias current in each of the three transistors. Also find the dc voltage at the output. Assume |VBE| = 0.7V, β = 100, and neglect the Early effect.
(b) Find the input resistance and the output resistance.
(c) Use the current-gain method to evaluate the voltage gain vo/vi.
– 0.52 mA, 1.04 mA, 2.1 mA, 0 V; (b) 4 kΩ, 65.5 Ω; (c) 8770 V/V