ANALOG FRONT END CIRCUIT AND METHOD FOR ADJUSTING DIRECT OFFSET THEREOF USING DIGITAL COMPENSATION FOR SMALL OFFSET AMOUNT AND ANALOG COMPENSATION FOR BIG OFFSET AMOUNT

摘要

PURPOSE: An analog front end circuit and a method for adjusting a direct offset thereof are provided to improve offset compensation performance by using digital compensation for a small offset amount while using analog compensation for a big offset amount. CONSTITUTION: An analog front end circuit includes an amplifier(110), an ADC(Analog to Digital Converter)(120), a digital low pass filter(130), a DAC(140), and a direct offset compensator(150). The amplifier has a first direct offset, inputs an analog signal at operational mode or a reference voltage at adjustment mode, and compensates an input signal to an analog direct offset compensation signal. The ADC has a second direct offset, and converts an output signal of the amplifier at operational mode or the reference voltage at adjustment mode to digital data. The digital low pass filter removes a high frequency band of the converted digital data. The direct offset compensator controls the mode selection of the amplifier and the ADC, generates a direct offset compensation signal for compensating the first and second direct offset and delivers the generated direct offset compensation signal to the DAC.