High performance 12-24 GHz RF front-end components fabricated in a commercial silicon germanium bipolar process.

Abstract

As silicon technology has advanced in the last five years, this has lead to a new area of silicon MMIC design. In this thesis, voltage controlled oscillators and sub-100 ps RF switching networks at 24 GHz as well as a 12 GHz phase shifter have been demonstrated in a SiGe bipolar process using extensive electromagnetic simulation for passive component design. The design of a differential VCO is optimized for K-band operation at 24 GHz using a novel differential circular inductor in the LC resonator. The compact differential VCO at 22.8 GHz has an average output power of 2.2 dBm, a SSB phase-noise of -104 dBc/Hz at 1 MHz offset and a FOM of -175 dB while maintaining a small footprint of only 230 x 290 mum<super> 2</super>. The proposed RF switching topology implements a differential absorptive SPDT at 24 GHz. An RF envelope switching time of 70 ps is achieved through the use of differential current steering. The switching time of the RF envelope is analyzed analytically and agrees well with simulated and measured results. The SPDT switch achieves 1.9 dB of gain at 24 GHz and an isolation of 35 dB. A 12 GHz phase shifter with integrated LNA is designed without the use of a FET or a quality diode as a switching element. The LNA implements a digital 180&deg; phase shift using a switched high-pass/low-pass network where the cascode stage of the LNA implements an SPDT function. Following the LNA is an analog phase shifter that uses varactors to implement a novel constant-impedance tuning technique which tunes the phase while simultaneously compensating for mismatch introduced by the variable load capacitance. The complete phase shifter has a measured gain of 3.7 +/- 0.5 dB at 11.5 GHz with a noise figure of 4.4 dB with a constant (+/-10&deg;) phase shift over more than 1 GHz of bandwidth.