Design of a differential diplexer based on integrated active inductors with 0.25 µm SiGeC process

This paper proposes the design of a differential diplexer based on integrated active inductors with the QUBiC4Xi library which is a 0.25 μm SiGeC process of NXP. It is dedicated to dense aperture arrays for the radio astronomy project SKA (Square Kilometre Array). The proposed system allows transmitting digital data as control command type via a RF (radio frequency) cable and isolating digital and RF bands. The RF signals operate in the [300 - 1500] MHz frequency band and the digital in the [10 - 20] MHz band. In this work, Agilent ADS (Advanced Design System) is used for design and simulations, and Cadence for the layout. The simulation results show that the RF gain is about -0.9 dB, its losses lower than 5.5 dB. The harmonics rejection coming from digital signals is better than 185 dB from 300 MHz with a digital clock of 10 MHz and its available voltage gain equals to 0 dB in the [10 - 20] MHz band.