Study On Excitation Source Of Film Bulk Acoustic Wave Sensor With Active Control Function

The sensors based on film bulk acoustic resonator have advantages of small volume, low cost and easy integration, and especially suitable for gas, protein, polymers biochemical detection. Film bulk acoustic sensor have high working frequency (up to several GHz), and its test mostly rely on network analyzer. Due to network analyzer is big and expensive, limiting the film body acoustic sensors extensive application. Because of sound energy loss caused resolution decline, the current resolution of film bulk acoustic sensor is difficult to meet low concentration small molecule detection requirements. Chongqing University proposed a method which uses active control technology to improve the resolution of the film bulk acoustic sensors. According to the detection circuit demand of film bulk acoustic sensors with active control functions , this paper researched the excitation and feedback control circuit of film bulk acoustic sensors and it has important significance to promote wide application of film bulk acoustic sensors.This paper according to sweep exciting source requirement of the new FBAR sensors, on the base of study sensor parameters and active control theory designed a kind of sweep exciting source which is able to produce active control signal. The main research contents including:(1) Based on the analysis of film research status and development trend, the method of active control to improve resolution of film bulk acoustic sensors is put forward. The mathematical model was established, and the effectiveness of active control method is proved by sensor by simulation results.(2) Based on the analysis of frequency synthesis principle and combined with practical testing requirements of film bulk acoustic, a scheme of frequency synthesizer which is combined with phase lock loop, direct digital frequency synthesis and frequency mixing is put forward and its feasibility is proved by simulation results. The hardware circuit and control software of frequency synthesizer are completed.(3) Based on the analysis of film bulk acoustic active control, a scheme of active control signal produce circuit is put forward, and its feasibility is proved by software. The hardware circuit and control software are completed.(4) Each circuit module debugging is completed, parts of frequency signal quality are tested and testing results meet the design requirements. Frequency synthesizer output signal phase noise is better than-70dBc @10KHz, and spur is better than - 35dBc. Active control circuit can realize the basic functions.