RF receiving apparatus
First Claim
Patent Images
1. A RF receiving apparatus comprisingan input terminal;
- a direct conversion system mixing circuit supplied at one input with RF signal inputted to the input terminal while at another input with an oscillation signal of local oscillator, for outputting a plurality of output signals whose phases are different to each other;
a suppression part supplied with the output of the mixing circuit;
an output terminal supplied with the output of suppression part;
a detector for detecting DC offset voltage contained in the output signals of the mixing circuit;
a control section interposed between the output of the detector and the input of the suppression part, wherein the control section outputting a signal to the suppression part for suppressing the DC offset voltage when the detector detected the DC offset voltage;
a level comparator supplied with the oscillation signal for comparing an oscillation signal level with a certain predetermined threshold value; and
a driving section interposed between the output of level comparator and the control section, when the level comparator detects that the signal level exceeded the threshold value, the level comparator signals the driving section to trigger the control section to control the suppression part to suppress the DC offset voltage.
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Abstract
A level comparator supplied with oscillation signal of local oscillator for comparing the signal level of oscillation signal with a certain predetermined threshold value, and a driving section interposed between the output of level comparator and a control section are provided. When the level comparator recognized that the signal level exceeded the threshold value, it puts the driving section into operation for bringing the control section into action.
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Citations
17 Claims
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1. A RF receiving apparatus comprising
an input terminal; -
a direct conversion system mixing circuit supplied at one input with RF signal inputted to the input terminal while at another input with an oscillation signal of local oscillator, for outputting a plurality of output signals whose phases are different to each other; a suppression part supplied with the output of the mixing circuit; an output terminal supplied with the output of suppression part; a detector for detecting DC offset voltage contained in the output signals of the mixing circuit; a control section interposed between the output of the detector and the input of the suppression part, wherein the control section outputting a signal to the suppression part for suppressing the DC offset voltage when the detector detected the DC offset voltage; a level comparator supplied with the oscillation signal for comparing an oscillation signal level with a certain predetermined threshold value; and a driving section interposed between the output of level comparator and the control section, when the level comparator detects that the signal level exceeded the threshold value, the level comparator signals the driving section to trigger the control section to control the suppression part to suppress the DC offset voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A RF receiving apparatus comprising
an input terminal; -
a first mixing circuit of direct conversion system supplied at one input with RF signal inputted to the input terminal while at another input with an oscillation signal of local oscillator; a second mixing circuit supplied at the one input with the output of first mixing circuit while at the another input with an output of fixed oscillator; a composer for composing a plurality of signals outputted from the second mixing circuit together; an output terminal supplied with the output of composer; a suppression part provided between the first mixing circuit and the second mixing circuit, or between the second mixing circuit and the composer; a detector for detecting DC offset voltage contained in the output signal of first mixing circuit; a control section interposed between the output of the detector and the input of the suppression part, wherein;
the control section outputting a signal to the suppression part for suppressing the DC offset voltage when the detector detected the DC offset voltage;a level comparator supplied with an oscillation signal outputted from either the local oscillator or the fixed oscillator for comparing signal level of the oscillation signal with a certain predetermined threshold value; and a driving section interposed between the output of level comparator and the control section are provided, when the level comparator recognized that the signal level exceeded the threshold value, the level comparator signals the driving section to trigger the control section to control the suppression part to suppress the DC offset voltage. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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Specification