An integrated SiGe bipolar VCO with linearized tuning behavior and ultra-wide tuning range for UWB FMCW local positioning systems

This paper describes an integrated voltage controlled oscillator (VCO) with linearized tuning behavior for ultra-wideband local positioning radar applications. The VCO is LC-resonator based and uses a tunable negative inductance cell (NI-cell) in conjunction with a differential junction varactor to achieve an ultra-wide, continuous frequency tuning range (FTR). A tuning linearization circuit is used to couple both tuning mechanisms to attain a more constant tuning sensitivity (K_VCO). The presented VCO offers a measured FTR from f_min = 3.365GHz to f_max = 7.677GHz. The tuning curve is linearized in a frequency range of 2.1GHz with a measured K_VCO-deviation of only ±10% around K_VCO = 775MHz over V, which corresponds to a relative FTR of 34%.