4.51 In the circuit shown in Fig. P4.51, I is a dc current and vs is a sinusoidal signal. Capacitors C1 and C2 are very large; their function is to couple the signal to and from the diode but block the dc current from flowing into the signal source or the load (not shown). Use the diode small-signal model to show that the signal component of the output voltage is
Figure P4.51
If vs = 10 mV, find vo for I = 1 mA, 0.1 mA, and 1 µA. Let Rs = 1 kΩ. At what value of I does vo become one-half of vs? Note that this circuit functions as a signal attenuator with the attenuation factor controlled by the value of the dc current I.
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