The Design Theory And Key Technology Research Of Closed Loop Self-excited Detection ASIC For Micro Resonant Sensor

The micromechaniacal resonant sensor has obvious advantages in the field of precise measurement because of its characteristics of small volume,light weight,good stability,semi-digital output.If the closed-loop self-excited detection of micro resonator sensor is designed by discrete devices,its circuit is not only complex,but also requires a large number of devices.In additon,this detection circuit is difficult to achieve fast,high-precision,low-cost measurement,because it is often susceptible to parasitic resistance,capacitance and noise.It is an inherent requirement and inevitable trend to design an ASIC of closed loop self-excitation and detection for micro resonant sensor,which can improve the measurement precison,reduce the cost of sensor and promote the industrialization of micro resonant sensor.Based on the design structure of discrete devices for micro-resonant sensor closed-loop self-excition and detection system.We propose an integrated circuit implementation structure of closed-loop self-excited and detection system.In this paper,the three key technologies of Gm-C filter and orthogonal signal generator in the signal processing circuit,and oscillator of the charge pump phase-locked loop were designed by the theoretical analysis and verified with using SMIC 0.13?m CMOS process on Cadence software.The main contents include:(1)The Gm-C filter utilizes transconductance amplifiers(OTA)and capacitors to implement a four-order Butterworth low-pass filter using a double-order cascade method,which can achieve a cutoff frequency(-3d B)is 74.5k Hz;(2)The quadrature signal generator realizes the phase change of the output signal by the control of the strobe signal,so that the phase of the fouroutput signals is precisely 90°,and the two frequency function is realized at the same time;(3)The oscillator adopts the structure of a five-stage ring-shaped voltage-controlled oscillator.The simulation results show that the frequency tuning range of the output signal is 49.21MHz~84.11 MHz when the control voltage changes from 405 m V to 475 m V,the center frequency is 66.69 MHz,and the phase noise of this center frequency is-113 d Bc/Hz@1MHz.