Patent ID: 7498885

Claim:
A voltage controlled oscillator comprising: at least one input port for receiving a control voltage; at least one voltage-to-current converter coupled to the input port for generating a control current in response to the control voltage, wherein the voltage-to-current converter further comprises; at least one first NMOS transistor having a gate terminal controlled by the control voltage at the input port; a first PMOS transistor with a source connected to a supply voltage, a drain connected to a drain of the first NMOS transistor; and a capacitor and resistor serially connected to a gate and the drain of the first PMOS transistor; at least one current controlled oscillator for generating an oscillating frequency output in response to the control current; and at least one compensation branch coupled to the voltage-to-current converter for generating a compensation current that increases the control current when the control voltage exceeds a predetermined value, wherein the compensation branch comprises a second NMOS transistor having a gate terminal controlled by the control voltage at the input port and a drain terminal connected to the drain terminal of the first NMOS transistor.