Resonant MEMS accelerometers have important application value in the field of
high-precision inertial detection due to their excellent characteristics such as
quasi-digital output, high resolution and low power consumption. The drive loop
and interface circuit are the core factors determining their detection accuracy
and operational stability. This paper deeply investigates the force-frequency
sensitive mechanism of resonant accelerometers, establishes a
mass-spring-damping dynamic model and an RLC equivalent electrical model, and
completes the full-process design of the closed-loop self-excited drive loop and
interface ASIC chip based on 0.18 μm CMOS technology. Key modules including a
high-gain operational amplifier, an integrated static error detection circuit
with full-wave rectification and PI control, a fully differential nonlinear
multiplier, a low-noise charge amplifier, and a low temperature coefficient
bandgap reference are designed and optimized. A closed-loop control system is
constructed to realize rapid start-up and constant-amplitude oscillation of the
resonant beam. Simulation results show that the temperature drift of the bandgap
reference circuit is 4.6482 ppm/°C over the full temperature range; the charge
amplifier achieves a gain of 102.128 dB with a low-frequency thermal noise of
10.33 nV; the drive loop can be stably
established within 100 ms, and the output fluctuation amplitude of the PI
controller is 284.6 μV; The total current of the circuit is 2.44 mA, and the
power consumption is 12.2 mW. The interface circuit designed in this paper has
the advantages of low noise, high integration and high precision, which meets
the high-performance application requirements of resonant MEMS accelerometers
and provides reliable technical support for the engineering implementation of
the device.