Design and performance analysis of CMOS tunable active inductor based voltage controlled oscillator

The performance of a Voltage Controlled Oscillator (VCO) is critical to meet the requirements of various wireless standards. This study highlights the use of a tunable active inductor (TAI) to build a VCO with a UMC 0.18 mu m process. The exclusion of the MOS varactor and the use of minimal transistors in the design provide significant improvement in the overall silicon area. The proposed single-ended TAI with the feedback resistor achieves a good quality factor (Q) and wide inductive bandwidth. The proposed tunable active inductor involves a power dissipation of 310 mu W at V-b = 0.8 V. The use of two symmetrical active inductors in the design of VCO gives a tuning range from 754 MHz to 1.89 GHz. The obtained tuning range can meet the requirement of L-band applications & IEEE 802.11ah standards. The total power consumption range under 1.0 supply voltage (V-dd) from 2.01 to 2.68 mW when the control voltage (V-b) is increased from 0.2 to 2.0 V. The phase noise and figure of merit (FOM) obtained at 1 MHz relative frequency from the carrier were -89.64 dBc/Hz and -150.4, respectively. The total layout area consumed by VCO with and without pad-frame was 43.03 mu m x 39.04 mu m and 22.11 mu m x 15.43 mu m, respectively, which is very low as compared to spiral inductor based VCO. Corner analysis, Monte Carlo analysis, temperature sweep analysis, and Stability analysis were carried out to validate the reliability and robustness of the VCO.