*4.53 In the circuit shown in Fig. P4.53, I is a dc current and v i is a sinusoidal signal with small amplitude (less than 10 mV) and a frequency of 100 kHz. Representing the diode by its small-signal resistance r d ,which is a function of I, sketch the small-signal equivalent circuit and use it to determine the sinusoidal output voltage V o , and thus find the phase shift between V i and V o . Find the value of I that will provide a phase shift of –45°, and find the range of phase shift achieved as I is varied over the range of 0.1 times to 10 times this value.