基于正交誤差對(duì)準(zhǔn)的MEMS陀螺測(cè)控電路設(shè)計(jì)

陳華+來(lái)強(qiáng)濤+郭桂良+郭江飛+韓荊宇

摘 要：傳統(tǒng)MEMS（Micro-Electro-Mechanical System）陀螺的相干檢測(cè)基于驅(qū)動(dòng)位移和科氏位移的相位關(guān)系，依賴于陀螺的工作模式，解調(diào)載波相位抖動(dòng)大，不易相位對(duì)準(zhǔn).為解決此問(wèn)題，本文提出了一種基于正交誤差對(duì)準(zhǔn)的不依賴陀螺工作模式的相干解調(diào)系統(tǒng).解調(diào)載波取自驅(qū)動(dòng)電路的PLL（Phase-Locked Loop）輸出，相位抖動(dòng)小，僅作載波使用，不代表驅(qū)動(dòng)位移信息.檢測(cè)通路插入移相器，使正交誤差相位滯后解調(diào)載波90°，則科氏位移信號(hào)與解調(diào)載波同相，完成檢測(cè).為驗(yàn)證該方法，本文研究了陀螺器件與接口電路之間的信號(hào)傳遞特性并進(jìn)行建模，設(shè)計(jì)了鎖相環(huán)、C/V（Capacitance/Voltage）轉(zhuǎn)換、移相器等核心電路，實(shí)現(xiàn)了一款完整的MEMS陀螺測(cè)控電路.測(cè)試結(jié)果表明：陀螺驅(qū)動(dòng)正常，檢測(cè)正確，刻度因數(shù)為1.415 mV/（°.s），零偏不穩(wěn)定度為108 °/h.結(jié)果驗(yàn)證了該檢測(cè)方法的有效性，并為后續(xù)進(jìn)一步提升性能提供了基礎(chǔ).該檢測(cè)方法也適用于其他振動(dòng)式MEMS陀螺的測(cè)控系統(tǒng).

關(guān)鍵詞：相干檢測(cè)； 正交誤差； 讀出系統(tǒng)； 陀螺； MEMS傳感器

中圖分類號(hào)：TN911.7 文獻(xiàn)標(biāo)志碼：A

Design of MEMS Gyroscope Interface Circuit Based onQuadrature Error Alignment

CHEN Hua1，2，LAI Qiangtao1，GUO Guiliang1，，GUO Jiangfei1，HAN Jingyu1

（1，Institute of Microelectronics of Chinese Academy of Sciences，Beijing 100029，China；

2.University of Chinese Academy of Sciences，Beijing 100049，China）

Abstract：Traditional synchronous demodulation of MEMS （Micro-Electro-Mechanical System） gyroscope is based on phase relationship of drive and sense positions. This relationship depends on the work mode of gyro. Moreover，the phase jitter of drive displacement is large，which makes the phase alignment of demodulator hard. To solve these problems，a new demodulation method based on quadrature error alignment was proposed，which is independent on work mode of gyro. Demodulator reference was extracted from PLL （Phase-locked loop） output，which has low jitter. Phase shifter of sense channel was used to delay quadrature error by 90°，compared with the reference signal. Therefore，Coriolis signal and the reference were automatically in-phase，and successful demodulation was achieved. To demonstrate this method，drive-mode and sense-mode circuits were elaborately implemented，and several critical blocks were care fully de signed. The demodulation of MEMS gyro shows that the vibration oscillation is stable and the operation of sense channel is correct. The scale factor is 1.415 mV/（°·s），and the bias instability is 108°/h. Moreover，the measurement results verify the validity of the demodulation method，providing solid foundation for further research. The method is also applicable to other vibratory MEMS gyroscopes.

Key words：coherent demodulation； quadrature error； readout systems； gyroscopes； MEMS sensors

相對(duì)于傳統(tǒng)陀螺儀，硅MEMS陀螺具有低成本、小尺寸、低功耗和高可靠性等優(yōu)勢(shì)，在消費(fèi)電子、汽車、工業(yè)控制及國(guó)防軍事等領(lǐng)域有著廣泛的應(yīng)用[1-2].近年來(lái)，隨著研究的不斷深入，MEMS陀螺性能已逼近慣導(dǎo)級(jí)[3-5]，并且成功地應(yīng)用于慣性測(cè)量單元中[6-8].由于加工誤差等非理想因素，陀螺驅(qū)動(dòng)模態(tài)和檢測(cè)模態(tài)之間存在比較嚴(yán)重的彈性耦合，使得在沒(méi)有輸入角速度時(shí)，檢測(cè)模態(tài)仍然有較大的正交誤差輸出.為抵抗各種擾動(dòng)，陀螺一般工作于低通區(qū)而非模態(tài)匹配區(qū)，這就造成科氏信號(hào)極其微弱.為了有效地檢測(cè)科氏信號(hào)，文獻(xiàn)[9-11]做了正交誤差消除工作，然后盡可能地將科氏信號(hào)放大，提升機(jī)械信噪比.消除正交誤差的方法有：在驅(qū)動(dòng)方向設(shè)計(jì)校準(zhǔn)梳指；在檢測(cè)方向的檢測(cè)電極上施加校準(zhǔn)力；對(duì)檢測(cè)方向的輸出電學(xué)信號(hào)進(jìn)行補(bǔ)償.后兩種方法會(huì)引入噪聲，污染檢測(cè)梳齒上的微弱科氏信號(hào)，所以高性能陀螺一般采用第一種方法.而本文研究對(duì)象由其他單位提供，沒(méi)有設(shè)計(jì)正交誤差校正梳指，所以本文要探索在正交誤差存在時(shí)怎樣將微弱的科氏信號(hào)較好地檢測(cè)出來(lái).endprint