Image Number 5 for United States Patent #7872600.
The present invention relates to a low cost analog to digital converter (ADC) and a method for converting an analog signal to a digital signal. The method includes the steps of: outputting a pulse modulation signal according to a digital value; performing a low-pass filtering to the pulse modulation signal to obtain a pulse averaged voltage; mixing a first proportion of the pulse averaged voltage and a second proportion of a voltage under test to obtain a composite voltage; comparing the composite voltage with a threshold voltage and adjusting the first digital value such that the composite voltage approaches the threshold voltage; and performing a complement operation to the digital value to obtain an analog to digital value corresponding to the voltage under test.
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