Electrical Engineering Archive: Questions from 2023-08-30

Consider the circuit shown, which is a model of an amplifier. The input voltage is vs and the output voltage is vo. The resistance ro, has value 100K, which means 100 kiloohm (note the strange spelling) or 100 x 10^3 ohm. The value of the resistor r_pi is 2.5K (2.5 X 10^3 ohm). The controlled current source has transconductance gm = 0.04 S. This means that if the voltage across r_pi is v_pi, the current source has magnitude gmr_pi. Something that often confuses newcomers to electronics is the ground symbol: In the diagram, this symbol appears 4 times. All the grounds are connected and are, in fact, the same node. Using the information provided, find an expression for the ratio Av = vo/vs, which is called the voltage gain of the amplifier.

The MOSFET and BJT in the adjacent circuit has the following parameters, k = 5 mA/V^2, VT= 0.7 V, beta = 85, VBE(Active) = 0.7 V, VBE(Saturation) = 0.8 V, VCE(Saturation) = 0.2 V a) Determine IB and I2. [CO2] 2 b) Determine IC. [CO2] 3 C) Determine IDS and I1. [CO2] 3