Research And Implementation Of Anti-radiation Capacitive Micro-accelerometer Interface Circuit

Capacitive acceleration sensors are one of the most developed types of acceleration sensors.Acceleration sensors working as key components of navigation guidance are widely used in carrier rockets or artificial satellites with the vigorous development of China's aerospace industry.In these environments,the acceleration sensor will be exposed to different levels and different forms of radiation which affects the function of the system.Therefore,acceleration sensors operating in these environments must have the ability to resist radiation damage.As a key part of the acceleration sensor,the performance of interface circuit must be optimized in terms of detection accuracy,power consumption,and noise.At the same time,for the capacitive acceleration sensor applied in radiant environments,its interface circuit is required that the total dose radiation resistance should not less than 100krad(Si).The design of the interface circuit of the anti-radiation capacitive micro-accelerometer is completed in this paper.The main tasks are:1.Optimization design and simulation of the main modules of the interface circuit,including: Low-noise optimization design of the preamplifier circuit in the capacitor voltage conversion circuit,apply the switched capacitor structure and related double sampling technology to the circuit to reduce the effects of parasitic capacitance,low frequency noise and offset;The capacitor voltage conversion circuit is designed and completed,realized the fully differential circuit structure based on the single-ended detection method;The programmable gain amplifier circuit is designed and completed,and the time-division multiplexing and time-division output can realize a fully differential circuit structure,the amplifier can also output continuous signals;The sallen-key low-pass filter with differential structure is designed and completed.The differential structure is realized by a fully differential difference amplifier while reducing the power consumption of the filter.By applying a variable capacitor array in the filter,the cut-off frequency can be adjusted.2.Analyze the total dose effect and single event effect of integrated circuits.Combined with the structure of the interface circuit,anti-irradiation reinforcement is mainly aimed at the total dose effect.The interface circuit adopts the layout reinforcement method,and the NMOSselects the H-gate structure.Using Sentaurus TCAD software,the H-gate NMOS and the ordinary bar-gate NMOS are compared and verified to obtain the transfer characteristic curve before and after irradiation.After modifying the electrical parameters of the NMOS in the interface circuit according to the curve,the anti-total dose effect simulation of the overall circuit is completed.3.Complete the layout design of the anti-radiation capacitive micro-accelerometer interface circuit.The interface circuit designed in this paper uses X-FAB's 0.18?m CMOS process.Its layout area is 3mm × 1.3mm.The circuit simulation results show that the conversion accuracy of the capacitor voltage conversion circuit is 82.27 m V / p F;The programmable gain amplifier can achieve approximately 0.05 d B steps and a gain change range of 0 to 17.5d B;The cutoff of the differential structure sallen-key low-pass filter frequency can be adjusted between0.29 k Hz and 24 k Hz.The interface circuit is powered by a 3.3V power supply with a total power consumption of 7.85 m W and a range of ± 2g to ± 200 g.It can resist at least 100Krad(Si)total dose effect.