Temperature compensated voltage controlled oscillator
AssigneeQUALCOMM Incorporated
InventorYue Wu
Life of this patent
Estimating the term…
Abstract
A VCO with temperature compensation is achieved using reverse biased diodes. The VCO includes an amplifier that provides the required signal gain, a resonator tank circuit that provides the required phase shift, and at least one frequency tuning circuit for tuning the frequency of the oscillator signal. Each frequency tuning circuit includes at least one tuning capacitor and at least one MOS pass transistor that connects or disconnects the tuning capacitor(s) to/from the resonator tank circuit. Each reverse biased diode may be a parasitic diode that is formed at a drain or source junction of a MOS transistor. The reverse biased diodes have capacitance that can be controlled by a reverse bias voltage to compensate for drift in the VCO oscillation frequency over temperature.
Claims19
An integrated circuit comprising:
- a voltage controlled oscillator (VCO) operative to provide an oscillator signal having a frequency;
- at least one reverse biased diode having a capacitance that is controlled by a reverse bias voltage to compensate for drift in the frequency of the oscillator signal due to temperature;
- a current source operative to provide a bias current;
- a current mirror operative to provide at least one version of the bias current;
- and
- a load resistor operative to receive the at least one version of the bias current and provide the reverse bias voltage
- wherein the at least one version of the bias current is selectable from among a plurality of possible versions of the bias current, and wherein different functions of reverse bias voltage versus temperature are obtained by selecting different combinations of bias current versions.
An integrated circuit comprising:
- a voltage controlled oscillator (VCO) operative to provide an oscillator signal having a frequency;
- at least one reverse biased diode having a capacitance that is controlled by a reverse bias voltage to compensate for drift in the frequency of the oscillator signal due to temperature;
- a look-up table operative to store a function of reverse bias voltage versus temperature, and
- a digital-to-analog converter operative to receive a temperature dependent value from the look-up table and provide the reverse bias voltage.
A wireless device comprising:
- a voltage controlled oscillator (VCO) operative to provide an oscillator signal having a frequency;
- at least one reverse biased diode having a capacitance that is controlled by a reverse bias voltage to compensate for drift in the frequency of the oscillator signal due to temperature;
- a current source operative to provide a bias current;
- a current mirror operative to provide at least one version of the bias current;
- and
- a load resistor operative to receive the at least one version of the bias current and provide the reverse bias voltage
- wherein the at least one version of the bias current is selectable from among a plurality of possible versions of the bias current, and wherein different functions of reverse bias voltage versus temperature are obtained by selecting different combinations of bias current versions.
An apparatus comprising:
- a voltage controlled oscillator (VCO) operative to provide an oscillator signal having a frequency;
- at least one reverse biased diode having a capacitance that is controlled by a reverse bias voltage to compensate for drift in the frequency of the oscillator signal due to temperature;
- a current source operative to provide a bias current;
- a current mirror operative to provide at least one version of the bias current;
- and
- a load resistor operative to receive the at least one version of the bias current and provide the reverse bias voltage
- wherein the at least one version of the bias current is selectable from among a plurality of possible versions of the bias current, and wherein different functions of reverse bias voltage versus temperature are obtained by selecting different combinations of bias current versions.
A method of performing temperature compensation for a voltage controlled oscillator (VCO), comprising:
- estimating temperature of the VCO;
- wherein the temperature of the VCO is estimated with a circuit component having a characteristic that is proportional to absolute temperature
- generating a reverse bias voltage for the estimated temperature, said generating comprising
- generating a bias current,
- selecting at least one version of the bias current from among a plurality of possible versions of the bias current based on a function of reverse bias versus temperature,
- applying the selected at least one version of the bias current to a load resistor to provide the reverse bias voltage;
- and
- applying the reverse bias voltage to at least one reverse biased diode to compensate for drift in frequency of oscillation for the VCO due to temperature.
Dependencies are inferred from the claim text.