CMOS-MEMS 摺疊樑式梳狀共振開關嵌入式開關鍵控/頻移鍵控通訊接收器

Abstract

本研究以CMOS 微機電摺疊樑梳狀共振式開關，製作出靜態零功耗的OOK/FSK接收器前端。於0.35-μm CMOS製程平台，能製作出共振開關整合解調電路的OOK/FSK訊號接收器。而由於共振開關機械結構，在其自然共振頻率下，結構共振現象，因此擁有頻率選擇性，及將輸入訊號放大的特性，其元件功率增益為27.7 dB，且此OOK/FSK訊號接收器於待機狀態的功耗僅0.2 μW，於35°C時，其壽命為3×10^6 cycles，於0°C時，其壽命為8×10^6 cycles。 微機電摺疊樑梳狀共振式開關由位於元件中間位置的可自由運動的梭子結構、梭子結構兩側呈梳狀的電極、固定於基板上的懸浮摺疊樑及輸出電極所組成。共振開關的驅動方式為施加一直流偏壓及交流驅動訊號於輸入電極，並於梭子結構樑上施加一直流偏壓，當交流電訊號的頻率與共振器機械結構的自然頻率吻合時，共振器產生共振，若梭子結構的運動位移大至撞擊輸出電極時，將可由輸出端採集到一周期性的熱切換訊號，其頻率為共振器結構的自然共振頻率。當共振開關於待機狀態或沒有接收到吻合自然頻率的RF訊號時，共振器不會共振，顯示了其頻率選擇的功能，且具有靜態零功耗的特性。 當共振開關接收一串OOK/FSK調變訊號，將產生熱切換訊號，可再藉由後端的包絡檢波器及兩組反相器組成的解調電路，成功解調變為一串二進位制'1'與'0'的訊號。

A CMOS-MEMS comb-driven mechanical resoswitch-embedded OOK/FSK receiver front end consuming zero quiescent power is presented. An integrated OOK/FSK receiver with the resoswitch assembling the demodulation circuits can realize on a 0.35-μm 2-poly-4-metal CMOS-MEMS platform. The resowitch yields the power gain of 27.7 dB by its channel-selecting and the signal amplification properties from the mechanical resonant behavior. An integrated OOK/FSK receiver consumes 0.2 μW in the sleep mode and reaches ~3×10^6 cycles at 35°C, ~8×10^6 cycles at 0°C in the operation mode. The comb-driven resoswitch consists of the suspended folded beams that are anchored to the substrate, the movable shuttle mass at the center and the comb fingers type electrode on the side of the shuttle and the output electrode. Applying a dc-bias voltage, an ac excitation voltage to the input electrode and a dc supply voltage on the shuttle to operate the resoswitch. When the frequency of the ac input signals matches the resonance frequency of the comb-driven resoswitch, the shuttle begins to vibrate dramatically to impact the output electrode, the periodic hot switching signals at the resonant frequency of the device occurs. This shows that the device can achieve the channel-selecting by producing the hot switching signals only on the resonance, which can demodulate the OOK/FSK signals, and also indicates that the device consumes nearly zero standby power when it doesn’t receive the RF input signals. The hot switching signals generating when applying the OOK/FSK modulated sig-nals turn out to be binary numbers 1’s and 0’s by demodulation backend circuits signal processing that are composed of the envelope detector and two inverters.