Converting an Analog Signal from a Magneto-Resistive Current Sensor Using a PLL Circuit

Analog to digital conversion is an important part of almost any electronic system that includes analog sensors. Currently, the characteristics of analog-to-digital converters (ADC) meet the most modern requirements of the electronics industry. These requirements include such parameters as noise immunity, implementation complexity, manufacturing cost, conversion accuracy, and frequency. This article describes the principle of converting an analog signal into a pulse duration based on a phase-locked loop (PLL). An analog signal received from a magneto-resistive current sensor, which is used to convert a magnetic field into a voltage. Building a PLL-based ADC gives a number of advantages. Negative feedback of the PLL circuit allows the device to minimize the errors of the passive circuit elements, including the effect of temperatures on the resistor ratings and filter interference at coherent conversion frequencies.