Capacitance Voltage Measurement Technique Based on a Frequency Counter and a Micro controller

An efficient and low-cost capacitance voltage measurement system with a 8 bit D/A output was developed for measurements of pn junction capacitance. This study reports the principle of operation, design aspects, as well as the experimentation and performance of the simultaneous C-V measurement of commercial pn junction diodes. The interface is able to measure low capacitance values in the order of pico farads and is implemented with a PIC16F628 micro controller, a 8 bit D/A, a voltage to frequency converter, and a comparator. The goal is to find the criteria to implement a low-noise system, so that, even with a short measuring time, low noise can be obtained. The simplistic design requires no phase sensitive detector and multiplexer to measure accurate data but incorporates a high degree of sensitivity and dynamic range, thus the cost of the design remains low and makes it suitable for semiconductor device characterizations. The auto range function has been performed by written micro controller software