US 2001/0019294 A1 · Voltage controlled oscillator

Abstract

A voltage controlled oscillator includes an amplifier having a positive feedback construction, configured to output an oscillation signal of a frequency corresponding to a control voltage supplied to a variable capacitor of a tank circuit having an inductor and the variable capacitor, and a variable current source configured to change an operation current supplied to the amplifier according to the control voltage. When a certain oscillation frequency at which phase noise becomes minimum is set as a reference point, the variable current source increases the operation current supplied to the amplifier as the oscillation frequency becomes lower than the certain oscillation frequency, or decreases the operation current supplied to the amplifier as the oscillation frequency becomes higher than the certain oscillation frequency. With this construction, a voltage controlled oscillator having a stable and sufficiently suppressed phase noise characteristic can be realized irrespective of the oscillation frequency.

Claims20

Dependent claims

A voltage controlled oscillator comprising:

an amplifier circuit having a positive feedback construction, configured to output a signal of an oscillation frequency corresponding to a control voltage supplied to a variable capacitance element of a tank circuit having an inductor and the variable capacitance element;
and
a variable current source configured to change an operation current supplied to said amplifier circuit according to the control voltage,
wherein, when a certain oscillation frequency at which phase noise becomes minimum is set as a reference point, said variable current source increases the operation current supplied to said amplifier circuit as the oscillation frequency becomes lower than the certain oscillation frequency, or decreases the operation current supplied to said amplifier circuit as the oscillation frequency becomes higher than the certain oscillation frequency.

1 more element

A voltage controlled oscillator comprising:

a control terminal to which a control voltage in a preset voltage range is supplied from an exterior;
a first current source configured to output a preset first current;
a second current source supplied with the control voltage from said control terminal, configured to output a second current controlled by the control voltage;
a current mirror circuit supplied with a third current obtained by adding the first and the second current, and configured to supply a fourth current which is a mirror current of the third current;
an oscillation circuit supplied with the fourth current of said current mirror circuit and including two variable capacitance diodes whose cathodes are connected together and supplied with the control voltage, an inductor connected between two anodes of said two variable capacitance diodes and cooperating with said variable capacitance diodes to oscillate at a frequency controlled by the control voltage, and at least one positive feedback circuit which is connected between the two anodes of said two variable capacitance diodes and into which the fourth current of said current mirror circuit flows;
and
two output terminals respectively connected to the anodes of said two variable capacitance diodes.

4 more elements

A voltage controlled oscillator comprising:

a control terminal to which a control voltage in a preset voltage range is supplied from an exterior;
a first current source into which a preset first current flows;
a second current source which is supplied with the control voltage from said control terminal and into which a second current controlled by the control voltage flows;
a current mirror circuit supplied with a third current obtained by adding the first and the second current and configured to supply a fourth current which is a mirror current of the third current;
an oscillation circuit supplied with the fourth current of said current mirror circuit and including two variable capacitance diodes, anodes of which are connected together and supplied with the control voltage, an inductor connected between two cathodes of said two variable capacitance diodes and cooperating with said variable capacitance diodes to oscillate at a frequency controlled by the control voltage, and at least one positive feedback circuit which is connected between the two cathodes of said two variable capacitance diodes and into which the fourth current of said current mirror circuit flows;
and
two output terminals respectively connected to the cathodes of said two variable capacitance diodes.

4 more elements

Dependencies are inferred from the claim text.

Voltage controlled oscillator

Life of this patent

Voltage controlled oscillator

Life of this patent

Abstract

Claims20