Vco circuit having low gain variation over different processes and

Abstract

A voltage controlled oscillator (VCO) circuit having low sensitivity to fabrication process variation, operating temperature variation, and power supply noise. The circuit of the present invention includes a current source controller, a bias circuit, and a first and second VCO cell. The first and second VCO cells are coupled to each other and are coupled to the bias circuit. The VCO circuit of the present invention also includes a VCO output for transmitting a VCO output signal to external electronics. A bias circuit current source is coupled to the bias circuit to transmit a bias circuit current from a power supply to the bias circuit. A first current source is coupled to the first VCO cell to transmit a first current from the power supply to the first VCO cell. A second current source coupled to the second VCO cell to transmit a second current from the power supply to the second VCO cell. The bias circuit current source, the first current source, and the second current source are each coupled to the current source controller to increase the power supply rejection ratio of the VCO circuit of the present invention. The first VCO cell and the second VCO cell each have respective first and second load transistors coupled to receive a bias compensation signal from the bias circuit such that the VCO output signal is less affected by changes in temperature and by fabrication process variation.