US 7,843,287 B2Granted

Active resonant circuit with resonant-frequency tunability

AssigneeRenesas Electronics Corporation

InventorsToru Masuda, Hiroshi Mori

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Abstract

The present invention is directed to provide a low-power-consumption wide-range RF signal processing unit having a small chip occupation area. A semiconductor integrated circuit has, on a semiconductor chip, a resonant circuit including a first capacitor having a capacitance which can be controlled by a first control signal of a first control terminal, and a gyrator for equivalently emulating an inductor by including a second capacitor having a capacitance which can be controlled by a second control signal of a second control terminal. The capacitance and the inductor form a parallel resonant circuit. At the time of changing parallel resonant frequency, the capacitances of the first and second capacitors are coordinately changed. The parallel resonant circuit is suitable for an active load which is connected to an output node of an amplifier.

Claims15

Dependent claims

A semiconductor integrated circuit comprising:

over a semiconductor chip, a resonant circuit including a first capacitor having a variable capacitance controlled by a first control signal applied to a first control terminal, and a gyrator for equivalently emulating an inductor by including a second capacitor having a variable capacitance controlled by a second control signal applied to a second control terminal,
wherein the first capacitor has a first terminal, a second terminal, and a third terminal, the third terminal of the first capacitor is coupled to the first control terminal, the variable capacitance between the first terminal and the second terminal of the first capacitor is controlled by the first control signal applied to the third terminal of the first capacitor,
wherein the second capacitor has a first terminal, a second terminal, and a third terminal, the third terminal of the second capacitor is coupled to the second control terminal, the variable capacitance between the first terminal and the second terminal of the second capacitor is controlled by the second control signal applied to the third terminal of the second capacitor.

A semiconductor integrated circuit comprising:

over a semiconductor chip, an amplifier and an active load connected to an output node of the amplifier,
wherein the active load comprises
a first capacitor having a variable capacitance controlled by a first control signal applied to a first control terminal;
and
a gyrator for equivalently emulating an inductor by including a second capacitor having a variable capacitance controlled by a second control signal applied to a second control terminal,
wherein the first capacitor has a first terminal, a second terminal, and a third terminal, the third terminal of the first capacitor is coupled to the first control terminal, the variable capacitance between the first terminal and the second terminal of the first capacitor is controlled by the first control signal applied to the third terminal of the first capacitor,
wherein the second capacitor has a first terminal, a second terminal, and a third terminal, the third terminal of the second capacitor is coupled to the second control terminal, the variable capacitance between the first terminal and the second terminal of the second capacitor is controlled by the second control signal applied to the third terminal of the second capacitor, and
wherein the first capacitor and the inductor are equivalently connected in parallel in the active load.

5 more elements

Dependencies are inferred from the claim text.