Apparatus for frequency direct conversion reception in mobile communication terminal and method thereof
First Claim
1. A method of frequency direct conversion in a mobile communication terminal, the method comprising:
- a radio frequency distributing step of distributing a radio frequency input signal into two signals having 180°
phase differences from each other by coupling;
a local signal distributing step of distributing a local signal provided from a local oscillator into two signals having the same phase, the local signal distributing step further comprising a step of suppressing amplitude noise of the local signal;
a signal mixing step of mixing the distributed radio frequency signals with the distributed local signals;
an amplifying step of amplifying each of the mixed signals;
a frequency band filtering step of allowing a low frequency band signal from each of the amplified signals to pass through in order to produce filtered signals; and
a cancelling and adding step of canceling out DC offsets included in the filtered signals and adding a wanted signal.
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Abstract
An apparatus for frequency direct conversion reception in a mobile communication terminal and method thereof are disclosed, by which a DC offset can be removed. The present invention includes a power distributor configured to distribute a radio frequency input signal into two signals having 180° phase differences, an equal phase directionality coupler configured to receive a single local signal provided by a local oscillator in order to distribute the single local signal into two output signals having the same phase, a pair of mixers, each configured to mix one of the two distributed local signals with one of the two distributed radio frequency signals in order to output a signal in downlink centering on a DC, a pair of baseband gain buffer amplifiers, each configured to deliver without load effect one of the two signals outputted from each of the pair of mixers to a rear end of the apparatus, a pair of pass filters, each configured to allow only low frequency band signals of the signals output by the pair of baseband gain buffer amplifiers to pass through, and a low frequency subtraction circuit configured to receive and compare the size of the signals that pass through the pair of pass filters.
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Citations
11 Claims
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1. A method of frequency direct conversion in a mobile communication terminal, the method comprising:
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a radio frequency distributing step of distributing a radio frequency input signal into two signals having 180°
phase differences from each other by coupling;a local signal distributing step of distributing a local signal provided from a local oscillator into two signals having the same phase, the local signal distributing step further comprising a step of suppressing amplitude noise of the local signal; a signal mixing step of mixing the distributed radio frequency signals with the distributed local signals; an amplifying step of amplifying each of the mixed signals; a frequency band filtering step of allowing a low frequency band signal from each of the amplified signals to pass through in order to produce filtered signals; and a cancelling and adding step of canceling out DC offsets included in the filtered signals and adding a wanted signal. - View Dependent Claims (2, 3)
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4. An apparatus for frequency direct conversion reception in a mobile communication terminal, the apparatus comprising:
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a power distributor configured to distribute a single radio frequency input signal into two output signals having 180°
phase differences by coupling;an equal phase directionality coupler configured to receive a single local signal provided by a local oscillator in order to distribute the single local signal into two output signals having the same phase; a limiter configured to suppress amplitude noise of the single local signal prior to being distributed into two output signals having the same phase by the equal phase directionality coupler; a pair of mixers, each configured to mix one of the two distributed local signals with one of the two distributed radio frequency signals in order to output a signal in downlink centering on a DC; a pair of baseband gain buffer amplifiers, each configured to deliver without load effect one of the two signals outputted from each of the pair of mixers to a rear end of the apparatus; a pair of pass filters, each configured to allow only low frequency band signals of the signals output by the pair of baseband gain buffer amplifiers to pass through; and a low frequency subtraction circuit configured to receive and compare the size of the signals that pass through the pair of pass filters. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11)
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Specification