Successive approximation register (SAR) analog to digital converter (ADC) dynamic range extension

摘要

An ADC, including a DAC which receives an analog input voltage and a digital input word from SAR logic, and generates a first voltage based on the analog input voltage and the digital word. The ADC also includes a comparator, which receives the first voltage and a reference voltage, and generates a second voltage based on the first voltage and on the reference voltage. The second voltage has a value corresponding with a sign of the difference between the first voltage and the reference voltage. The ADC also includes the SAR logic circuit which receives the second voltage from the comparator. The SAR logic generates a digital output word based on a second voltages received from the comparator. A difference between the minimum input voltage on the maximum input voltage is substantially equal to two times a difference between reference voltage and the minimum input voltage.