<FONT face=Verdana>A 155Mbps QAM demodulator is designed for digital millimeter-wave communication. A novel parameter named Signal Resource Quantity (SRQ) incorporating peak and average power ratio

demodulation threshold and bandwidth was introduced to find out the best order of QAM for high-speed millimeter-wave communication. The 4~64QAMs win in 4~1024QAMs according to their SRQs. How gain deviation of AGC and carrier leakage affect the demodulation performance were studied. A zero-jitter timing recovery detector was implemented by the theories of pre-filtering Nyquist raised sine signal with small roll-off factor. An improved PFD carrier recovery algorithm with adaptive power threshold was proposed to avoid wrongly capturing constellation points in the case of high-order QAM. The design has been applied to a millimeter-wave link successfully

and the algorithms work robustly. The demodulation loss was less than 2dB when the BER was equal to 1E-8.