Design Of The CMOS Integrated Detection Circuit Based On Tuning Fork Quartz Micro-Gyroscope

Tuning-fork quartz micro-gyroscope is used to measure the rotation object's angle or angular velocity in the relative inertia space and it determine the orientation or navigation of carriers. In recent years, because of its tiny bulk, low power consumption and high reliability, it has been widely used in military and civilian spheres. However, there are micro-gyroscope devices alone can not detect the output signal of angular velocity by gyroscope, it also need a reasonable detection circuit to detect the tiny charge amounts that produced by gyroscope and convert it into required voltage signal. Then, it can be used to deal with the appropriate follow-up treatment and obtain the angular velocity signal that measured by micro-gyroscope. Therefore, how to design a good detection circuit of tuning-fork quartz micro-gyroscope is vitally important.This paper designs a detection circuit based on tuning-fork quartz micro-gyroscope, it contains low-noise input stage, high-gain amplification stage and full-swing output stage. In the circuit design, using the PMOS full-differential input and the folded cascade structure, through adjusting the transistor parameters to reduce noise and improve the gain; The structure with full-differential output of low-noise input stage and full-differential input of high-gain amplification stage, reduces the system's offset voltage and offset temperature coefficient; The bootstrap reference current mirror with initiate circuit and a special frequency compensation measure, which makes use of transconductance with capacitances, enhance precision, antijamming ability and stability of the hole circuit.Set each transistor's parameters based on 0.5μm CMOS process, use H-Spice software in detection circuit and demodulation circuit for simulation, parameter adjustment and verification. The simulation results contain: the open-loop gain gets to 128.13dB, phase margin 88°, SR gets to 2V/μs, the output noise is below 40nV/ HZ at very low frequency, full output swing. The simulation results of output signal show that each 5×10?15C change of input charge amount can provide about 1mV change of output voltage. The voltage signal that obtained by the demodulation circuit compares with the input angular velocity signal has a very highly linearity. From the simulation data, we can see that the detection circuit has high gain, high precision and low noise characteristics, and it can be better realized to detect the tiny charge amounts that come out from the tuning-fork quartz micro-gyroscope, and provide a good match for the next signal processing circuit.Finally, use Cadence software to design the detection circuit layout, which takes fully account of the matching between each device, reduces their parasitics, improves the circuit performance, then through the design rule checking and layout consistency compared with the circuit to verify the correctness of the layout design.