Voltage controlled oscillator with linear capacitance

摘要

The voltage controlled oscillator comprises an amplifier and an oscillating system comprising an inductor and a first and second variable capacitor connected in series, each having a capacitance varying according to its control voltage. The capacitance of one of the variable capacitors varies in the same direction as its control voltage and the capacitance of the other variable capacitor varies in the opposite direction to its control voltage. A capacitor having a fixed capacitance can be connected in series or in parallel with the first and second variable capacitors. The first and second variable capacitors are preferably formed by transistors, respectively of PMOS and NMOS type. An additional series of additional first and second variable capacitors can be connected in parallel with the first and second variable capacitors.