An inductor-less LC-VCO for Ka band using 90nm CMOS

Voltage Controlled Oscillator plays a vital role of frequency synthesizer in various ultra wideband applications of Ka band like multi-band OFDM (MB-OFDM), Radar and imaging systems. In the proposed topology, an LC-VCO with wide tuning range employing complementary cross-coupled nMOS as core is presented. The simulated active inductor is used for fine frequency tuning and pMOS varactors concede coarse frequency tuning. The dearth of passive components of inductor leads to lesser chip area than the circuit with passive spiral inductor. The amalgamation active inductor circuit with all transistors as constituents and digitally controlled 7-bit switchable capacitor bank comprising IMOS varactors consisting of pMOS varactors lead to a wide tuning range. The VCO is designed to get a frequency range of 37.7 GHz to 41.9 GHz with a center frequency of 40 GHz. Phase noise is calculated to be -78.8 dBc/Hz at 1 MHz offset and consumes 20 mW of power from the supply voltage of 0.9 V in 90 nm technology process node.