AMPLIFICATION SYSTEM FOR DETECTING MASK

摘要

PURPOSE: An amplification system for detecting a mask is provided to reduce the distortion of an amplifier used in the amplification system. CONSTITUTION: A control system(104) is prepared with a micro controller(124) for controlling a frequency composer(126) to heterodyne a signal output to a line(103) from an amplifier(102), and a mixer(106) receives the output of the frequency composer and the amplifier. Herein, the output of the mixer is supplied to a band pass filter(108), and the filter removes a frequency element within the band of the heterodyned signal. In addition, the amplifier receives the filtered signal and supplies the amplified output to an analog-digital converter(120). The digital output of the analog-digital converter is supplied to a digital signal processor(122) to analyze the digital signal, and the micro controller analyzes the measurement values of the present and past energy and outputs a control signal for regulating a phase and gain.