Design of the voltage clamp delay cell VCO using quadrature phase for low phase noise and high speed operation

We have designed a new current-mode low-voltage, low-power supply, high-frequency CMOS VCO (Voltage Controlled Oscillator) circuit. The main purpose of this new circuit is to obtain low phase noise with more than 1 GHz oscillation frequency from one battery cell. The fully differential-type voltage clamp delay cell VCO enables extremely low supply voltage operation due to wide tuning range and superior linearity between the oscillator frequency and control voltage of a ring oscillator because of low phase noise. A design which combines the transitions of each delay cell output enables the VCO's high frequency operation. The characteristics of the designed VCO were examined by the HSPICE and SABER circuit simulation. Operation with a 3.3 power supply and 3.6 GHz oscillation frequency was verified.