A high voltage zero-static current voltage scaling ADC interface circuit for micro-stimulator

This paper describes a SAR ADC interface circuit, where the input sensing voltage from a bipolar high voltage domain is linearly translated into the low voltage domain where the SAR ADC operates. The proposed interface circuit employs the principle of charge transfer amplifier to deliver information between two different power domains, in one step, without static power consumption, even if both domains do not share the the same ground voltages. To implement the charge transfer scheme using standard asymmetric LDMOS, we propose a novel dynamic body biased high voltage transmission gate. Prototype simulation using a standard 24V BCDMOS process shows that the proposed circuit draws 2.12μW of power when it senses a voltage that swings between +10V and -10V at 1 kSPS sampling frequency.