Design Of PZT Sensor Readout Circuit

Piezoelectric porous lead zirconate titanate(PZT)ceramics is one kind of ceramic materials which can transform mechanical energy and electrical energy.Piezoelectric sensors based on piezoelectric characteristics are widely used in sonar system,weather detection,remote sensing,environmental protection,household appliances,medical and communication fields.It is difficult to design high precision read out circuit of PZT sensor,due to weak signal from piezoelectric elements.Therefore,the key point of this paper is how to suppress noise and improve the readout circuit precision of PZT sensor.Meanwhile,the integrated design of readout circuit is implemented.The applicability of PZT sensor readout circuit is proved.The main work in this paper is summarized as follows:Based on MATLAB modeling and simulation,this paper simulates the range of relevant parameters under various factors to guide the subsequent circuit design.Then the overall circuit design and construction,including automatic gain control(AGC)and ADC two main parts.The sensor first transmits the signal to a variable gain amplifier for amplification,and then converts it into a digital code by an ADC with its own low-frequency noise suppression.Automatic gain control reads digital code and automatically selects the range of gain amplification.The automatic gain is composed of variable gain amplifier and gain control.Programmable gain amplifier is used as VGA in this paper to improve the adaptability of readout circuit to different amplitude signals.The ADC circuit is mainly composed of modulator and filter.At the same time,the power consumption and area are reduced.The modulator uses a third-order sigmadelta ADC,which is composed of a switching electrical volume divider,a one-bit comparator,a feedback DAC,a two-phase non-overlapping clock,and a chopper clock.The digital extraction filter is mainly realized by FIR filter.Finally,the layout design and post simulation of the simulation part are completed.The design of the analog front end of the PZT sensor readout circuit is based on the smic 0.18 ?m process.The oversampling rate of readout circuit is set to 128.The whole circuit works under the power supply of 3.3V and the signal bandwidth of 1k Hz.After the simulation of whole circuit,SNDR is 95.6d B and the effective number of bits(ENOB)is 15.58 bits.It is proved that the readout circuit of PZT sensor in this paper is feasible and effective.