Figure 8-1 shows the problems associated with trying to rectify small signals with a simple diode ciruit.
If a sine wave having a peak-to-peak voltage of 2 V is the input signal to the half-wave rectifier of Figure8-1a, the peak output voltage is only about 0.3 V.
On the other hand, a 1-V peak-to-peak sine-wave signal will not allow a typical silicon diode to conduct at all, giving a zero output voltage (Figure 8-1b).