AIM : i)To analyse the performance of a RC coupled CE amplifier circuit with respect to gain,band width,& distortion
THEORY:
RC is the most widely used coupling as it provides excellent audio fidelity. A coupling capacitor is used to connect output of first stage to the input of the second stage. Resistances R1, R2, R5, R3, R4 and R10 form biasing and stabilisation network. Emitter bypass capacitors C5 and C6 offer low reactance paths to the signals. The coupling capacitor C3 transmits ac signal and blocks dc signal. Cascaded stages amplifies signal and overall gain is improved. The total gain is less than the product of gains of individual stages. Thus overall gain of two stages is A = A1 x A2, where A1 = Voltage gain of first stage and A2 = Voltage gain of second stage
When ac signal is applied to the base of the transistor Q1, its amplified output appears across the collector resistor R9. It is given to the second stage for further amplification and signal appears with more strength. Frequency response curve is obtained by plotting a graph between frequency and gain in dB. The gain is constant in midband frequency range and gain decreases in low and high frequency ranges. The gain decreases in the low frequency range due to coupling capacitor C3 and at high frequencies due to junction capacitance Cbe .