應用於13.56MHz ISM band的非同步QPSK解調變器

A Non-coherent QPSK Demodulator in 13.56MHz ISM Band Applications

楊凱傑(Kai-Chieh Yang)

指導教授 ： 李順裕

國立中正大學/工學院/電機工程學系/碩士(2012年)

摘要

本論文提出兩組載波頻率為13.56MHz ISM Band的QPSK解調變器，第一是不含有鎖相迴路的架構，解調變方式是檢測轉態時所產生的特殊波形，第二是含有鎖相迴路的架構，其解調變的架構為修改過的單位元取樣，兩個解調變器的設計目標為低功耗和高資料傳輸率並可應用於類似視網膜晶片等植入式生醫系統中。
第一個解調變器為Offset QPSK 的解調變器，因Offset QPSK有較少的轉態，可使用兩種偵測調變方塊的Edge counter和Small pulse detection完成解調變的動作，利用這兩種電路偵測四種轉態並使用簡單的組合電路輸出資料，其整體電路的功耗只有5.2uW和6.78MHz的資料速率，達到極低的Energy 0.77 pJ/bit。
第二個解調變器為QPSK的解調變器，因為考慮到通道和發射端所會產生的噪音和失真，因此修改了單位元取樣的調變方法，使其能在考慮到非理想效應的情況下正確的解回資料，實現的方法使用了鎖相迴路的方式產生取樣時脈，另外使用symbol timing recovery和訓練序列來校正資料並決定時脈，最後利用產生的取樣時脈和資料決定時脈來進行解調變，其整體電路的功耗只有109.7 uW和3.39 MHz的資料速率，達到Energy 0.0323 nJ/bit。

關鍵字

解調變器 ； 低功率 ； 高資料量 ； 低能量 ； 偏移四相移鍵解調變器 ； 四相移鍵解調變器 ； 視網膜晶片 ； 植入式生醫系統

並列摘要

The thesis develops two QPSK demodulators for 13.56MHz ISM band. First, the first demodulator is implemented without phase-locked loop structure. The transition waveform is detected for the demodulation. Furthermore, the phase-locked loop is adopted for the second demodulator. The modified single bit sampling method is used for the this demodulation. The design challenges for these two demodulators are low power and high data rate which are suitable for retinal prosthesis.
The first demodulator is an offset QPSK demodulator which has the advantage of fewer transition between the transformation of quadrature signals. Two circuits including edge counter and small signal detection can be sued for demodulation, because four offset QPSK transitions can be detected and the data can be easily recovered. The proposed demodulator only consumes 5.2μw at 6.78-MHz data rate. This circuit also achieves ultra-low energy with 0.77 pJ/bit.
The second demodulator is a QPSK demodulator which has the tolerance for the noise and distortion from transmitted device and channel. The modified single bit sampling method is used for the noise and distortion robustness. A phase-locked loop is used to generate the sampling clock for the data detection. Moreover, the symbol timing recovery and training sequence are designed for clock synchronization and data decision. The demodulator only consumes 109.7μw at 3.39 MHz Data rate. This circuit also achieves ultra-low energy with 0.0323nJ/bit.

並列關鍵字

Demodulator ； Low-power ； High-Data-rate ； Low-Energy ； Offset Quadrature Phase Shift Keying (QPSK) demodulator ； Quadrature Phase Shift Keying (QPSK) demodulator ； Retinal Prosthesis ； Biomedical Implantable Systems

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