| Summary: | 碩士 === 國立成功大學 === 電機工程學系碩博士班 === 90 === In coherent demodulation, a coherent carrier is needed to demodulate signal successfully. Phase-locked loop can be used to realize the phase synchronization. For example, Costas loop uses two parallel phase-locked loop to recover the carrier. On the other hand, in noncoherent demodulation, one may use differential coding and decoding techniques to demodulate signal without knowing exact carrier phase. This will greatly simplify the circuit.
In the thesis, firstly the demodulation theory and circuit topology are given. Then, oscillator circuit design using semi-lump elements is presented. Next, cascode topology are used in mixer design to improve LO-to-RF isolation. Finally, the result of system simulations and experiments are given. The bit error rate of I/Q demodulator using analog multiplier is compared to that using digital multiplier. The modulation and demodulation technique proposed in this research are also suitable for other M-ary signal modulation and demodulation.
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