Even harmonic direct-conversion receiver, and a transmitting and receiving apparatus using the same
First Claim
1. An even harmonic direct-conversion receiver, comprising:
- an antenna configured to receive and output a received wave having a received wave frequency;
an amplifier configured to amplify said received wave and to output an amplified signal;
a bandpass filter disposed after said amplifier and configured to output a bandpass limited amplified signal;
a local oscillator configured to output a local oscillation wave having an oscillation wave frequency at approximately half said received wave frequency;
an even harmonic quadrature mixer configured to mix said bandpass limited amplified signal with said local oscillation wave and to output a baseband signal;
a signal processing circuit configured to demodulate said baseband signal; and
a filter device disposed before said amplifier, said filter device configured to pass said received wave and to substantially suppress a frequency band corresponding to said oscillation wave frequency.
1 Assignment
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Accused Products
Abstract
If a local oscillation wave of a frequency approximately half the received signal frequency is input to a low noise amplifier 2, a dc offset voltage caused by the nonlinearity of the amplifier is produced, thus degrading reception sensitivity. This problem is resolved by disposing before the low noise amplifier 2 a filter means, such as a bandpass filter 12, band-elimination filter 13, or high pass filter 14, with characteristics for passing the received wave and suppressing a frequency band at approximately half the received wave frequency, thus preventing a radiation wave at substantially the same frequency as the local oscillation wave from being input to the low noise amplifier 2. A filter circuit 15 is also provided in the low noise amplifier 2 as a means for eliminating a radiation wave input to the low noise amplifier 2.
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Citations
12 Claims
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1. An even harmonic direct-conversion receiver, comprising:
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an antenna configured to receive and output a received wave having a received wave frequency;
an amplifier configured to amplify said received wave and to output an amplified signal;
a bandpass filter disposed after said amplifier and configured to output a bandpass limited amplified signal;
a local oscillator configured to output a local oscillation wave having an oscillation wave frequency at approximately half said received wave frequency;
an even harmonic quadrature mixer configured to mix said bandpass limited amplified signal with said local oscillation wave and to output a baseband signal;
a signal processing circuit configured to demodulate said baseband signal; and
a filter device disposed before said amplifier, said filter device configured to pass said received wave and to substantially suppress a frequency band corresponding to said oscillation wave frequency. - View Dependent Claims (2, 3, 4, 5)
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6. An even harmonic direct-conversion receiver, comprising:
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an antenna configured to receive and output a received wave having a received wave frequency;
a first amplifier configured to amplify said received wave and to output a first amplified signal;
a second amplifier configured to amplify said first amplified signal and to output a second amplified signal;
a bandpass filter disposed after said second amplifier and configured to output a bandpass limited second amplified signal;
a local oscillator configured to output a local oscillation wave having an oscillation wave frequency at approximately half said received wave frequency;
an even harmonic quadrature mixer configured to mix said bandpass limited second amplified signal with said local oscillation wave and to output a baseband signal;
a signal processing circuit configured to demodulate said baseband signal;
a bandpass filter disposed after said second amplifier; and
a filter device disposed before one of said first amplifier and said second amplifier, said filter device configured to pass a corresponding output of one of said antenna and said first amplifier and to substantially suppress a frequency band corresponding to said oscillation wave frequency. - View Dependent Claims (7, 8, 9, 10)
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11. A transmitting and receiving apparatus, comprising:
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an antenna configured to receive and output a received wave having a received wave frequency;
an even harmonic direct-conversion receiver having a receiver amplifier configured to amplify said received wave and to output an amplified signal, a bandpass filter disposed after said receiver amplifier and configured to output a bandpass limited amplified signal, a local receiver oscillator configured to output a local oscillation wave having a receiver oscillator frequency at approximately half said received wave frequency, a receiver even harmonic quadrature mixer configured to mix said bandpass limited amplified signal with said local receiver oscillation wave and to output a received baseband signal, a receiver signal processing circuit configured to demodulate said received baseband signal, and a receiver filter device disposed before said amplifier, configured to pass said received wave and to substantially suppress a frequency band corresponding to said oscillation wave frequency; and
a transmitter having a transmitter signal processing section configured to process a signal output from said even harmonic direct conversion receiver and to output a transmission baseband signal, a transmitter signal processing circuit configured to modulate said transmission baseband signal, a local transmitter oscillator configured to output a local transmitter oscillation wave having a transmitter oscillator frequency of approximately half said transmission signal frequency, and a transmitter even harmonic quadrature mixer configured to mix said local transmitter oscillation wave with said transmission baseband signal and to output a transmission signal.
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12. A transmitting and receiving apparatus, comprising:
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an antenna configured to receive and output a received wave having a received wave frequency;
an even harmonic direct-conversion receiver having a first receiver amplifier configured to amplify said received wave and to output a first amplified signal, a second receiver amplifier configured to amplify said first amplified signal and to output a second amplified signal, a bandpass filter disposed after said second receiver amplifier and configured to output a bandpass limited second amplified signal, a local receiver oscillator configured to output a local receiver oscillation wave having a receiver oscillation frequency of approximately half said received wave, a receiver even harmonic quadrature mixer configured to mix said bandpass limited second amplified signal with said local receiver oscillation wave and to output a receiver baseband signal;
a receiver signal processing circuit configured to demodulate said receiver baseband signal; and
a receiver filter device disposed before one of said first amplifier and said second amplifier, said receiver filter device configured to pass a corresponding output of one of said antenna and said first receiver amplifier and to substantially suppress a frequency band corresponding to said oscillation wave frequency; and
a transmitter having a transmitter signal processing section configured to process a signal output from said even harmonic direct conversion receiver and to output a transmission baseband signal, a transmitter signal processing circuit configured to modulate said transmission baseband signal, a local transmitter oscillator configured to output a local transmitter oscillation wave having a transmitter oscillator frequency of approximately half said transmission signal frequency, and a transmitter even harmonic quadrature mixer configured to mix said local transmitter oscillation wave with said transmission baseband signal and to output a transmission signal.
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Specification