Page 241 - Build Your Own Transistor Radios a Hobbyists Guide to High-Performance and Low-Powered Radio Circuits

FIGURE 14-9 Q1 collector output for various input sine-wave input levels
at 0.026, 0.052, 0.104, and 0.416 V peak. The X axis is time, whereas the
Yaxis is the amplitude.
With the base of Q2 AC grounded, the collector current from Ql is

/ +
, J
where lEE is the DC emitter "tail" current, and I sig is the AC signal current for

modullating, which means that I sig = gm3 X V RF = IRF sin (2nF2)t
If VBl is a sinusoid signal at a frequency of Fl at about 1 volt peak to peak, then
the expression

[ ( B1)/ 1 + (\, BI ) ] = { I + ~ i in 211"' t +i in 211 t + ~ 'in 21T t
'IT
+~in21T7' 1) + .. . ]}

which approximately represents a square-wave signal. And if IsigS IRF[sin(2IJF2)tJ,
then