A BJT is being used as a switch and is triggered whenever thebase-emitter voltage v(t) rises above 0.15 volts. The voltage v(t)is sinusoidal and changes according to v(t )= 0.23cos( 100π t)+ 0.16sin(100π t + 0.4) .
a) Express v(t) a sine function only (use trigonometric identities).
b) i) What other method can be used to obtain expression ina)? Obtain the same expression using this method.
ii) Why does this other method fail if it is used to find a single expression for
v 2 ( t ) =0.23cos(100 πt ) +0.16sin(200 πt )
while it works fine for
v(t) = 0.23cos(100πt) + 0.16sin(100πt)
c) Using the expression in a), calculate the percentage timeper cycle the BJT is in cut-off mode.