Study on Six-Port Demodulator with Anti-parallel Diode Pair Detection

The direct conversion receivers have unique advantages in wireless communications owing to their circuit simplicity and the high level of the circuit integration. A novel six-port direct conversion demodulator utilizing anti-parallel diode pair (APDP) detection is presented in this paper. The block diagram of the six-port demodulator is fabricated and the corresponding mathematic formulas of the demodulator are educed. The influence of the I/Q across interferences, the DC-offset and the second order intermodulations (IM2) on the performance of the demodulator is studied. The results show that the present six-port demodulator can decrease the I/Q across interferences with a baseband signal processing method. Compare with the single diode detection, the APDP configuration have perfect performance on suppression the DC-offset and the IM2. The present work is expected to be useful for the design of the advanced demodulator with high frequency and ultra-wideband.