An Ultra-Wide Tuning Range SiGe VCO with 192.5dBc/Hz FoMT Using 6-bit Switched Capacitor Bank and Centrosymmetric Core Layout

An ultra-wide tuning range LC voltage-controlled oscillator (VCO) with an excellent FoM
T
of 192.5dBc/Hz at 10 MHz offset in 130-nm SiGe BiCMOS is presented in this work. The VCO employs a pair of HBTs to build cross-coupling configurations and works in class-C mode. To obtain the tuning range as wide as possible, a 6-bit switched capacitor bank is applied to expand the tuning range with a pair of varactors. Simultaneously, a centrally symmetrical layout is used to reduce the parasitic effect of layout asymmetry of the HBT cross-coupling pair on the circuit under class-C working conditions. The proposed VCO possesses phase noise of -113dBc/Hz at 1MHz offset and -138.3dBc/Hz at 10MHz offset, and can continuously tune between 9.58-13.8GHz (36.1%). The FoM
T
of this VCO is competitive in this frequency band, which shows a great advantage in the application of 5G millimeter-wave or satellite communication.