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US 6,175,728 B1Granted
Direct conversion receiver capable of canceling DC offset voltages
AssigneeNEC Corporation
InventorMasataka Mitama
Life of this patent
Estimating the term…
Abstract
A direct conversion receiver comprising mixers for mixing a received radio frequency signal and a local oscillation signal in frequency, a signal processing unit for converting the output signal of the mixers into a baseband signal, a delta-sigma modulator for detecting offset voltage from the output signal of the signal processing unit, a holding circuit for supplying offset canceling voltage for canceling the offset voltage, and a switch of supplying the output signal of the mixers to the delta-sigma modulator during a given period and supplying the offset canceling voltage sent from the holding circuit to the output side of the mixers.
Claims18
A direct conversion receiver comprising:
- frequency mixing means for mixing a received radio frequency signal and a local oscillation frequency signal;
- signal converting means for converting an output signal of said frequency mixing means into a baseband signal;
- offset voltage detecting means for detecting offset voltage from an output signal of said signal converting means;
- offset canceling means for supplying an offset canceling voltage for canceling the offset voltage in the output signal of said frequency mixing means, correspondingly to the offset voltage detected by said offset voltage detecting means;
- and
- switching means for supplying the output of said frequency mixing means to said offset voltage detecting means during a given period, and supplying the offset canceling voltage sent from said offset canceling means to the output side of said frequency mixing means during a period other than the given period.
3 more elements
A direct conversion receiver comprising:
- frequency converting means for mixing a received radio frequency signal and a local oscillation frequency signal;
- signal converting means for converting an output signal of said frequency converting means into a baseband signal;
- offset voltage detecting means for detecting an offset voltage from the output signal of said frequency converting means during a given period;
- and
- offset canceling means for canceling the offset voltage in the output signal of said frequency converting means during a period other than the given period, correspondingly to the offset voltage detected by said offset voltage detecting means,
- wherein it is applied to a communication system of Time Division Multiplex Access method,
- said offset voltage detecting means detects offset voltage during a period other than an assigned time slot of a present receiver, and
- said offset canceling means supplies the offset canceling voltage to the output side of said frequency converting means during a period of the assigned time slot of the present receiver.
5 more elements
A direct conversion receiver comprising:
- frequency converting means for mixing a received radio frequency signal and a local oscillation frequency signal;
- signal converting means for converting an output signal of said frequency converting means into a baseband signal;
- offset voltage detecting means for detecting an offset voltage from the output signal of said frequency converting means during a given period;
- and
- offset canceling means for canceling the offset voltage in the output signal of said frequency converting means during a period other than the given period, correspondingly to the offset voltage detected by said offset voltage detecting means,
- when it is applied to a communication system of Frequency Division Multiplex Access method,
- said offset voltage detecting means detects offset voltage during a period corresponding to a pilot signal part of a received frame, and
- said offset canceling means supplies the offset canceling voltage sent from said offset canceling means to the output side of said frequency converting means during another period.
5 more elements
A direct conversion receiver comprising:
- frequency mixing means for mixing a received radio frequency signal and a local oscillation frequency signal;
- signal converting means for converting an output signal of said frequency mixing means into a baseband signal;
- offset voltage detecting means for detecting an offset voltage from the output signal of said signal converting means;
- offset canceling means for supplying offset canceling voltage for canceling offset voltage in the output signal of said frequency mixing means, correspondingly to the offset voltage detected by said offset voltage detecting means, so as to overlap the output signal of said frequency mixing means;
- and
- switching means for blocking a supply of the output signal of said offset voltage detecting means to said offset canceling means during a given period, and supplying the output signal of said offset voltage detecting means to said offset canceling means during a period other than the given period.
3 more elements
Dependencies are inferred from the claim text.