The zero-bias capacitance of a silicon pn junction diode is \(C_{j o}=0.02 \mathrm{pF}\) and the built-in potential is \(V_{b i}=0.80 \mathrm{~V}\). The diode is reverse biased through a \(47-\mathrm{k} \Omega\) resistor and a voltage source.

(a) For \(t<0\), the applied voltage is \(5 \mathrm{~V}\) and, at \(t=0\), the applied voltage drops to zero volts. Estimate the time it takes for the diode voltage to change from \(5 \mathrm{~V}\) to \(1.5 \mathrm{~V}\). (As an approximation, use the average diode capacitance between the two voltage levels.)

(b) Repeat part (a) for an input voltage change from \(0 \mathrm{~V}\) to \(5 \mathrm{~V}\) and a diode voltage change from \(0 \mathrm{~V}\) to \(3.5 \mathrm{~V}\). (Use the average diode capacitance between these two voltage levels.)