COMPLEX VALUED DELTA SIGMA PHASE LOCKED LOOP DEMODULATOR

摘要

The demodulator is a multiple stage demodulator. The first stage is aconversion stage which converts an incoming signal into a first complexrepresentation. The second stage is a direct digital synthesizer (DDS)/mixerwhich synthesizes a signal to be mixed with the first complex signal andperforms the mixing operation to produce a second complex output. This secondcomplex signal is controlled by a bitstream fed back from the third stage - aphase quantizer stage. The bitstream represents the quantized phase differencebetween the synthesized signal and the first complex signal. The DDS/mixerstage then measures the synthesized signal for any phase difference from theincoming signal through the feedback inherent to a PLL, the bitstream thusprovides an output that gives the frequency of the desired signal. As a sidebenefit, the real component of the second complex signal, provides anamplitude estimate of the desired signal.