A 30–50 GHz Wide Modulation Bandwidth Bidirectional BPSK Demodulator/ Modulator With Low LO Power

A 30-50 GHz wide modulation bandwidth bidirectional binary phase shift keying (BPSK) demodulator/modulator using a 2 mum standard GaAs HBT process is presented in this letter. A single balanced mixer with HBT PN-junction diodes is employed in the circuit design. With a local oscillator (LO) power of 0 dBm, this letter demonstrates a maximum conversion loss of 13 dB, a modulation bandwidth of wider than 3 GHz, and a LO-to-RF isolation of better than 45 dB. The BPSK demodulation or modulation can be performed at the same input/output ports of the circuit, and therefore it can be applied to millimeter-wave (MMW) gigabit bidirectional communication systems to further reduce the complexity of the transceivers.