A 122-GHz SiGe-Based Signal-Generation Chip Employing a Fundamental-Wave Oscillator With Capacitive Feedback Frequency-Enhancement Martin Jahn, Student Member , IEEE,H e r b e r t K n a p p, Member , IEEE

Abstract

This paper presents a highly integrated and fully balanced signal generation block comprising a fundamental-wave voltage-controlled oscillator (VCO), an output buffer, and a con- figurable frequency divider stage (prescaler). The VCO introduces a negative resistance structure in conjunct ion with capacitive cross-coupling. This compound structure allows fundamental oscillation to be sustained at high frequencies while providing wide tuning ranges. The capabilities of th e capacitive feedback were analyzed using a linear tra nsistor model, and boundary conditions, which support the early design phase, were derived. The chip was fabricated in a SiGe tec hnology with 300-GHz HBTs. The output frequency of the monolithic microwave integrated circuit is centered at 122 GHz and provides a tuning range of 16 GHz at an average singl e-sideband phase noise of 95 dBc/Hz at 1 MHz offset frequency. Possible applications include ISM applications at 122 GHz and sh ort-range radar systems with wide tuning ranges.