Single stage transformer coupled class A power amplifier

Single stage transformer coupled class A power amplifier uses a transistor with maximum dissipation capability of 2.5 watts. The maximum a.c. power in the load is:

In class A transformer coupled

η = 0·5 =	P_o(ac)
	P_i(dc)

where,
P_o(ac) → maximum ac power in the load
P_i(dc) → maximum applied dc power to the amplifier
given that P_{D (max)} = 2.5

0.5 =	P_o(ac)
	P_D(max) + P_o(ac)

0.5 =	P_o(ac)
	2.5 + P_o(ac)

1.25 + 0.5 P_{o (ac)} = P_{o (ac)}
0.5 P_{o (ac)} = 1.25

or P_{o (ac)} =	1·25	= 2.5 watts.
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