Carrier leak reduction transmitter circuit
AssigneeRenesas Technology Corp.
InventorsSatoshi Tanaka, Yukinori Akamine
Life of this patent
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Abstract
A transmitter circuit has two mixers that modulate a carrier wave according to an input signal, outputs a signal having information in a phase and an amplitude, detects a DC offset in each of the mixers, and adds a DC voltage that corrects the detected DC offset to the input signal of the mixers. The mixer is a double balanced mixer having two load resistors, and the transmitter circuit has a resistor that is connected between a node of two load resistors and a power supply, a limiter amplifier that amplifies a signal, and a control unit that changes first and second potentials using a signal that is outputted by the limiter amplifier. The first and second potentials become a potential of the DC voltage that corrects the DC offset.
Claims12
A transmitter circuit that outputs a first signal having information in a phase and an amplitude, the transmitter circuit comprising:
- a mixer that modulates a carrier signal according to an input signal;
- a detector that detects a DC offset of the mixer;
- and
- an adder that adds a DC voltage which corrects the detected DC offset to the input signal of the mixer,
- wherein the mixer comprises a double balanced mixer that includes two first resistors for differential output,
- wherein the transmitter circuit further comprises:
- a second resistor that is connected between a node of the two first resistors and a power supply;
- a limiter amplifier that amplifies a second signal that appears at the node when potentials of a pair of input terminals that input differential input signals of the double balanced mixer are alternately set to a first potential and a second potential;
- and
- a control unit that changes the first potential and the second potential by using a third signal that is outputted by the limiter amplifier,
- wherein a feedback loop that reduces the amplitude of the second signal by changing the first potential and the second potential, and
- wherein the first potential and the second potential which are converged in the feedback loop is a potential of the DC voltage which corrects the DC offset.
A transmitter circuit, comprising:
- a mixer that conducts frequency conversion of an input signal by using a carrier signal to output a first signal that has been converted in frequency;
- a detector that detects a DC offset of the mixers;
- and
- an adder that adds a DC voltage that corrects the detected DC offset to the input signal of the mixer,
- wherein the mixer comprises a double balanced mixer that includes two first resistors for differential output,
- wherein the transmitter circuit further comprises:
- a second resistor that is connected between a node of the two first resistors and a power supply;
- a limiter amplifier that amplifies a second signal that appears at the node when potentials of a pair of input terminals that input differential input signals of the double balanced mixer are alternately set to a first potential and a second potential;
- and
- a control unit that changes the first potential and the second potential by using a third signal that is outputted by the limiter amplifier,
- wherein a feedback loop that reduces the amplitude of the second signal by changing the first potential and the second potential, and
- wherein the first potential and the second potential which are converged in the feedback loop is a potential of the DC voltage which corrects the DC offset.
Dependencies are inferred from the claim text.