VIEWS: 36 PAGES: 2 POSTED ON: 8/15/2011
Tutorial 6 Q1 For the RC-coupled class-A amplifier shown in Figure 1, determine – (i) the total dc power, Pi(dc) , drawn from the supply, ( 0.94W ) (ii) the ac load power, Po(ac) , and ( 50.8mW ) (iii) the maximum efficiency, η , of the amplifier. ( 5.4% ) +24V RC R1 330 Ω 4.7 kΩ RL 330 Ω β = 150 R2 1kΩ RE 100 Ω Figure 1 Q2 For the Transformer-coupled class-A amplifier shown in Figure 2a, the circuit component values results in a dc base current of 6mA, and the input signal (Vi) results in a peak base current swing of 4mA. Figure 2b shown the output characteristic for the transistor T1. Assume the primary winding resistance and RE is very small (~ 0Ω). Determine – (i) the total dc power, Pi(dc) , drawn from the supply, ( 1.4W ) (ii) the dc and ac load line, (iii) the output compliance, ( 5.53V ) (iv) the ac power delivered to the 8Ω speaker and ( 0.47W ) (v) the maximum efficiency, η , of the amplifier. ( 34% ) Derive the maximum theoretical efficiency for a transformer-coupled class-A amplifier. (50%) +VCC = 10V N1 : N2 RL = 8Ω R1 3:1 ib(peak) = 4mA IB = 6mA Vi T1 R2 RE Figure 2a Figure 2b Tutorial 6 Q3 For the class-AB amplifier shown in Figure 3, determine – (i) the values of VCEQ, VB(Q1), VB(Q2) and ( 10V , 10.7V , 9.3V ) (ii) the maximum efficiency of the amplifier. ( 78% ) +VCC = 20V R1 = 15kΩ Q1 D1 D2 RL = 32Ω Q2 R2= 15kΩ Figure 3
"Tutorial C Power Amplifier"