- 學位論文
適用於生醫訊號傳輸之頻移鍵入收發機
A Frequency-Shift-Keying Transceiver for Bio-Medical Signals
摘要
無線傳輸技術在近年來大幅進步，在不同的領域應用都快速的發展，其中，無線生醫訊號系統是非常熱門的研究領域之一。本論文的目標在設計一套適合傳送生醫訊號的無線傳輸介面。此介面的要求為低耗電、中等傳輸速率、高正確性。 頻移鍵入 (Frequency-Shift-Keying) 調變符合以上三個條件，適合此類系統使用。 調變器使用一分數型所相迴路（Fractional-N Phase-Locked Loop）。其優點為容易改變頻率實現調變、產生頻率準確。分數型架構讓鎖定速度、迴路頻寬和頻率解析度可以同時達到相當好的表現。三角積分調變器（Delta-Sigma Modulator）也用在此架構中，以減低雜訊效應。 接收機採用直接降頻的方式來進行解調。低雜訊放大器放大接收到的微弱訊號後，集柏特混波器（Gilbert Mixer）將之與本地振盪器(Local Oscillator)產生的訊號混波，包含資訊的訊號被降至基頻（Baseband）。此訊號經由限制放大器 (Limiting Amplifier) 放大，其振幅將達到最大，趨近於方波波形，可被當成數位訊號處理。一個數位式的解調器接在限制放大器之後，以計算週期長度的方式，把資訊解調
並列摘要
Wireless technique has greatly improved in recent years. Applications in many different field arise quickly. Biomedical-signal wireless sensor system is one of the hottest research targets. The objective of this thesis is to design a wireless interface suitable for biomedical signals. The requirements of such a interface are low power consumption、medium transmission speed and high precision. Frequency-shift-keying fits in with these requirements and is adopted. A fractional-N type phase-locked loop is used as the modulator. It has the advantages of convenience to change the frequency and high precision. Fractional-N architecture allows the lock speed、loop bandwidth and frequency resolution to be optimized at the same time. A delta-sigma modulator is also used to reduce noise. The receiver adopts direct conversion topology. Low noise amplifier enhances the weak received signal and a Gilbert mixer down-converts it to baseband by mixing it with the local oscillator signal. A limiting amplifier limits the down-converted signal to rail-to-rail level assembling the waveform of a square wave witch can be view as digital pulses. A counter-based digital demodulator extracts the data.