Diode Limiter

Objective

To design and study a Diode Limiter.

Introduction

DA diode limiter is an electronic circuit designed to clip or limit an alternating current (AC) supply voltage or an audio signal to a preset value. This is typically necessary where the supply voltage is larger than needed or powerful audio signals require compression to prevent overloads. Diode limiter circuits achieve this clipping function by placing one or two Zener diodes in parallel with the supply or signal. A single diode will only clip one half of the wave form while a pair of diodes will clip both negative and positive parts of the cycle. Accurate limiting is possible due to the known voltage limiting characteristics of different Zener diodes.


Fig.1 Expected Waveform of Diode Limiter.

Any AC power supply or audio signal is made up of a sinusoidal or sine wave form. A sine wave is a smooth repetitive series of positive and negative peaks with a zero value in the center of the wave form. The height between these peaks and the zero point define the amplitude or size of the signal or supply. A diode limiter can control the amplitude of a signal if it is too large by either clipping one half of the wave or both. Producing a precise reduction in amplitude with a diode limiter is possible due to the unique, accurate voltage limiting abilities of Zener diodes.