Analysis and design of a high linearity quadrature demodulator based on SiGe BiCMOS process

In the paper, a high linearity quadrature demodulator based on SiGe BiCMOS process is designed and implemented for 400MHz to 2GHz wide band wireless system. The 3rd intermodulation cancellation technique is applied to improve linearity. A negative feedback structure is applied to quadrature Gilbert mixer to lower its input impedance. RC polyphase network is analyzed and designed to increase the quadrature performance in wide band. Measurement results show excellent performance in the designed frequency range from 400MHz to 2GHz.