A Low Phase Noise Cross-Coupled VCO for X-Band Applications in 0.13μm SiGe BiCMOS Technology

This paper presents a low-power low phase noise voltage-controlled oscillator (VCO) in X-band frequencies fabricated in IHP's 130nm SiGe BiCMOS process (f(t)/f(max) of 250/340 GHz). The core of the VCO is based on a cross-coupled (CC) pair. The phase noise performance of the VCO improved by utilizing a passive LC filter in the tail. The VCO employs a varactor linearization technique to increase the tuning range (TR) and further widen TR achieved by using a thick gate oxide MOS varactor and switched capacitor banks. The VCO core is isolated using cascode buffers, allowing proper driving capability. The design achieves phase noise of -119.25 dBc/Hz at 1 MHz offset at the center frequency and TR of 15.88%. The circuit occupies a die area, including the output balun and pads, of 2.08mm(2) and consumes 28.7mW power.