Conversion of amplitude modulated square wave signal from current sensor to pulse duration using PLL circuit

Abstract

At the moment, almost any electronic product incorporates measuring sensors for converting physical quantities. These devices produce a signal of measurement information in a form suitable for transmission and further conversion. As a rule, the output signal from the measurement sensors undergoes first preprocessing such as amplification, filtering, modulation, etc. After preprocessing the prepared signal, various architectures of analog‑to‑digital converters (ADC) are used. The choice of ADC depends on the parameters of the conversion signal and the dynamic characteristics of the sensors used. This paper considers converting a square‑amplitude modulated signal from a current sensor to a pulse width using a phase‑locked loop (PLL). The architecture of the ADC based on the PLL circuit allows obtaining a linear dependence of the output signal duty cycle on the value of the measured input current. The layout of the device is implemented on a printed circuit board, the main components of which are: current sensor, which is a bridge circuit of magnetoresistive conductors; phase‑sensitive rectifier and microcircuit of a two‑channel PLL circuit made inTechnological Center.