Differential charge transfer based accelerometer

An integrated circuit for measuring a differential change between first and second mutual capacitances of a MEMS circuit, wherein receiver electrodes of said first and second mutual capacitances are joined to form a common electrode, said integrated circuit performing charge transfer measurements to transfer charge to a reference capacitor, with a plurality of current mirror structures used to scale and control the amount of charge being transferred to said reference capacitor, wherein a digitally controlled variable capacitor is used to change the amount of charge stored in said reference capacitor, with said integrated circuit performing first and second charge transfer measurements, each comprising a number of charge transfer cycles used to transfer charge from the common electrode to the reference capacitor, said first measurement characterised by driving a transmit electrode of said first capacitance high first, said second measurement characterised by driving a transmit electrode of said second capacitance high first;

• and wherein the integrated circuit compensates for parasitic capacitances in said MEMS circuit through the use of a sample-and-hold circuit selectively connected to said common electrode to maintain its voltage during a charge phase of a charge transfer cycle.