US 8,476,970 B2 · Interface for MEMS inertial sensors

Abstract

In a high-performance interface circuit for micro-electromechanical (MEMS) inertial sensors, an excitation signal (used to detect capacitance variation) is used to control the value of an actuation signal bit stream to allow the dynamic range of both actuation and detection paths to be maximized and to prevent folding of high frequency components of the actuation bit stream due to mixing with the excitation signal. In another aspect, the effects of coupling between actuation signals and detection signals may be overcome by performing a disable/reset of at least one of and preferably both of the detection circuitry and the MEMS detection electrodes during actuation signal transitions. In a still further aspect, to get a demodulated signal to have a low DC component, fine phase adjustment may be achieved by configuring filters within the sense and drive paths to have slightly different center frequencies and hence slightly different delays.

Claims15

Dependent claims

An integrated circuit for interfacing with a MEMS sensor, comprising:

a electrostatic actuation controller configured to generate an actuation signal and an excitation signal and to receive a sense information signal;
a drive capacitance-to-voltage converter responsive to a signal from the MEMS sensor for producing a drive signal, and a sensing capacitance-to-voltage converter responsive to a signal from the MEMS sensor for producing a sense signal;
a demodulator coupled to the drive signal and the sense signal for demodulating sense information carried by the sense signal to produce the sense information signal;
and
time alignment circuitry coupled to at least one of the drive signal and the sense signal for, prior to multiplying, performing time alignment of the drive signal and the sense signal by creating a relative delay between the drive signal and the sense signal, comprising:
a fine time delay circuit comprising at least one filter configured to create a fine time delay between the drive signal and the sense signal.

3 more elements

Dependencies are inferred from the claim text.

Interface for MEMS inertial sensors

Life of this patent

Interface for MEMS inertial sensors

Life of this patent

Abstract

Claims15