NOISE REDUCTION CIRCUIT FOR CANCELING LEAKAGE SIGNAL
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Abstract
In a noise reduction circuit, a transistor circuit amplifies an input signal and outputs an output signal with supply of power from the DC voltage source via a power supply line circuit. The canceling signal adding circuit acquires and attenuates a part of the output signal, to generate a canceling signal having a phase substantially opposite to a phase of a leakage signal leaking to the power supply line circuit, and having an amplitude substantially the same as an amplitude of the leakage signal.
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Citations
19 Claims
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1-10. -10. (canceled)
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11. A noise reduction circuit comprising:
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a signal amplifier for amplifying an input signal and outputting an output signal with supply of power from a power source via a power supply line circuit; and a signal adding circuit for acquiring and attenuating a part of the output signal from the signal amplifier, to generate a canceling signal having a phase substantially opposite to a phase of a leakage signal leaking to the power supply line circuit, and having an amplitude substantially the same as an amplitude of the leakage signal, and for substantially canceling the leakage signal by adding the canceling signal to the leakage signal, wherein the power supply line circuit comprises; a low-impedance part for substantially shorting a line of the leakage signal with a ground to ground the leakage signal at a frequency of the leakage signal; and a high-impedance part for setting a connection point between the low-impedance part and the signal amplifier to a substantially open-circuited state at the frequency of the leakage signal, and wherein the signal adding circuit adds the canceling signal to the leakage signal at a position which is closer to the power source than the low-impedance part. - View Dependent Claims (12, 13, 14, 15)
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16. A signal amplifier comprising a noise reduction circuit, the noise reduction circuit comprising:
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a signal amplifier for amplifying an input signal and outputting an output signal with supply of power from a power source via a power supply line circuit; and a signal adding circuit for acquiring and attenuating a part of the output signal from the signal amplifier, to generate a canceling signal having a phase substantially opposite to a phase of a leakage signal leaking to the power supply line circuit, and having an amplitude substantially the same as an amplitude of the leakage signal, and for substantially canceling the leakage signal by adding the canceling signal to the leakage signal, wherein the power supply line circuit comprises; a low-impedance part for substantially shorting a line of the leakage signal with a ground to ground the leakage signal at a frequency of the leakage signal; and a high-impedance part for setting a connection point between the low-impedance part and the signal amplifier to a substantially open-circuited state at the frequency of the leakage signal, wherein the signal adding circuit adds the canceling signal to the leakage signal at a position which is closer to the power source than the low-impedance part, and wherein the signal amplifier comprises; a power terminal connected to the power supply line circuit; and an output terminal for outputting the output signal.
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17. A wireless communication apparatus comprising a noise reduction circuit, the noise reduction circuit comprising:
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a signal amplifier for amplifying an input signal and outputting an output signal with supply of power from a power source via a power supply line circuit; and a signal adding circuit for acquiring and attenuating a part of the output signal from the signal amplifier, to generate a canceling signal having a phase substantially opposite to a phase of a leakage signal leaking to the power supply line circuit, and having an amplitude substantially the same as an amplitude of the leakage signal, and for substantially canceling the leakage signal by adding the canceling signal to the leakage signal, wherein the power supply line circuit comprises; a low-impedance part for substantially shorting a line of the leakage signal with a ground to ground the leakage signal at a frequency of the leakage signal; and a high-impedance part for setting a connection point between the low-impedance part and the signal amplifier to a substantially open-circuited state at the frequency of the leakage signal, wherein the signal adding circuit adds the canceling signal to the leakage signal at a position which is closer to the power source than the low-impedance part, and wherein the wireless communication apparatus comprises a transmitter for transmitting the signal amplified by the signal amplifier.
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18. A wireless communication apparatus having a receiver for receiving a wireless signal having a predetermined frequency,
wherein the wireless communication apparatus comprises a noise reduction circuit comprising: -
a signal amplifier for amplifying an input signal and outputting an output signal with supply of power from a power source via a power supply line circuit; and a signal adding circuit for acquiring and attenuating a part of the output signal from the signal amplifier, to generate a canceling signal having a phase substantially opposite to a phase of a leakage signal leaking to the power supply line circuit, and having an amplitude substantially the same as an amplitude of the leakage signal, and for substantially canceling the leakage signal by adding the canceling signal to the leakage signal, wherein the power supply line circuit comprises; a low-impedance part for substantially shorting a line of the leakage signal with a ground to ground the leakage signal at a frequency of the leakage signal; and a high-impedance part for setting a connection point between the low-impedance part and the signal amplifier to a substantially open-circuited state at the frequency of the leakage signal, wherein the signal adding circuit adds the canceling signal to the leakage signal at a position which is closer to the power source than the low-impedance part, wherein the high-impedance part is a transmission line having a length of a quarter of a wavelength of the leakage signal, wherein the low-impedance part is a capacitor for passing therethrough a signal having the frequency of the leakage signal, wherein the input signal is a square wave signal, and wherein the power supply line circuit attenuates a leakage signal which is a part of frequency components of the square wave signal, at one of (a) a frequency of a wireless signal used in the wireless communication apparatus, (b) an intermediate frequency related to the wireless signal, and (c) a frequency of a baseband signal.
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19. A noise reduction method including the steps of:
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amplifying an input signal and outputting an output signal by a signal amplifier with supply of power from a power source via a power supply line circuit; and acquiring and attenuating a part of the output signal, to generate a canceling signal having a phase substantially opposite to a phase of a leakage signal leaking to the power supply line circuit, and having an amplitude substantially the same as an amplitude of the leakage signal, wherein the power supply line circuit comprises; a low-impedance part for substantially shorting a line of the leakage signal with a ground to ground the leakage signal at a frequency of the leakage signal; and a high-impedance part for setting a connection point between the low-impedance part and the signal amplifier to a substantially open-circuited state at the frequency of the leakage signal, and wherein the canceling signal is added to the leakage signal at a position which is closer to the power source than the low-impedance part.
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Specification