A 77 GHz Wideband Image Rejection Modulator with High LO-RF Isolation in 0.13 μm SiGe BiCMOS Technology

This paper presents an E-band image rejection modulator fabricated in 0.13-mu m SiGe BiCMOS technology. A double-balanced Gilbert-cell based image rejection architecture is applied to provide high conversion gain and good linearity. For image signal elimination, a Lange coupler together with transformers constitutes the phase-shifting network to generate accurate quadrature-phase LO signals. For better isolation and balance, a Wilkinson power divider is employed to combine RF power. At IF frequency of 1 MHz and LO power of 0 dBm, the modulator achieves a measured conversion gain of over 6 dB from 73 GHz to 84 GHz, with a peak value of 7.9 dB at 77 GHz. The image rejection of the modulator is better than 28 dB from 66 GHz to 86 GHz and the LO-RF isolation is better than 25 dB from 67 GHz to 86 GHz. The measured output 1 dB compression point (OP1dB) is -1.9 dBm. Compared with other works, the proposed modulator achieves very wide bandwidth of image rejection and LO-RF isolation.