Takashi Ohira
Since the early 1900s, single series diode rectifiers have long been used in amplitude modulation signal detection. One may think that their design theory is already well matured. Let us check and see if that is true.
A simple rectifier is excited by a sinusoidal-wave voltage source and loaded with a resistor, as shown in Figure 1. The RF source voltage is expressed in the time domain as \begin{align*}{\nu}_{s}{(}{t}{)} = {\left[{V}\right.}_{P}\left.{{V}_{Q}}\right]\left[{\begin{array}{c}{\sin{\omega}{t}}\\{\cos{\omega}{t}}\end{array}}\right]\end{align*}
Figure 1. The rectifier consists of a finite inductor L, an ideal diode D, and an infinite capacitor ${C}_{\infty}$. We now focus on the dc output voltage ${V}_{o}$.
where VP and VQ are called the in-phase and quadrature components, respectively. Defining the time origin t = 0 at the moment when the diode turns on, we can predict the dc output voltage ${V}_{o}$ from ${V}_{P}$ and ${V}_{Q}$. Which among the following is equal to ${V}_{o}$?
The circuit configuration is so simple that we just need quite primitive algebra to solve the problem. However, notice that intuitive prediction may not always be true. A crucial key is the zero-voltage switching (ZVS) law, which applies when the diode turns on. See last month’s solution column [1] to be sure of what the ZVS law physically signifies.
[1] T. Ohira, “Solution to last month’s quiz,” IEEE Microw. Mag., vol. 24, no. 2, pp. 92–93, Feb. 2023, doi: 10.1109/MMM.2022.3218178.
Digital Object Identifier 10.1109/MMM.2022.3226632