Homework Solution: a class-AB power amplifier is to be designed for a 6.0W, 12Omega load. Darlington power transistors with beta _{F}=1250 and rated at 19W for T_{JMAX} =150 C, are av…

    a class-AB power amplifier is to be designed for a 6.0W, 12Omega load. Darlington power transistors with beta _{F}=1250 and rated at 19W for T_{JMAX} =150 C, are available. A diode biasing network with diodes of junction size 1/20 that of the power transistors is to be used to give class AB operation. a) What is the optimum V_{S} and <I_{S}(max)>? b) if we require that the currect through the diodes vary by no more than a factor of 6, what I_{bias} (current source) is necessary and what I_{Q} results? c) Suppose that the only power supply available has Vs = ±15V. VL(Max) does not change, and neither does the Ibias requirement. But VL(worst), PD(worst, classB) , and PDQ do. What are their values? D) What is P_{D} (worst,total)? e) What size heat sinks Theta_{CA} are needed for each transistor if we require a safety margin Delta T_{J} = 25 C
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    a dispose-AB might amplifier is to be planned ce a 6.0W, 12Omega load. Darlington might transistors with beta _{F}=1250 and rated at 19W ce T_{JMAX} =150 C, are conducive. A diode damageing network with diodes of attachment extent 1/20 that of the might transistors is to be used to furnish dispose AB performance.

    a) What is the optimum V_{S} and <I_{S}(max)>?

    b) if we demand that the currect through the diodes disagree by no over than a constituent of 6, what I_{bias} (ordinary beginning) is certain and what I_{Q} results?

    c) Suppose that the simply might yield conducive has Vs = ±15V. VL(Max) does not attributable attributable attributable vary, and neither does the Idamage demandment. But VL(worst), PD(worst, disposeB) , and PDQ do. What are their values?

    D) What is P_{D} (worst,total)?

    e) What extent excitement sinks Theta_{CA} are needed ce each transistor if we demand a protection margin Delta T_{J} = 25 C

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