The doping concentrations in a silicon pn junction are Nd = 5 × 1015 cm^3 and Na = 1017 cm^3. The zero-bias junction capacitance is Cjo = 0.60 pF. An inductance of 1.50 mH is connected in parallel with the pn junction. Calculate the resonant frequency fo of the circuit for reverse-bias voltages of (a) VR = 1 V, (b) VR = 3 V, and (c) VR = 5 V.