US5603114A
Expired / Lapsed
US
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Distortionless receiving circuit
Assignee: NEC Corp
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Filing: 1994-11-01
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Granted: 1997-02-11
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Expires: 2014-11-01
Abstract
Abstract A distortionless receiving circuit used in a radio receiver to reduce degradation of the receiving sensitivity in case of a relatively lower receiving electric field. The circuit has a radio frequency amplifier, a mixer for frequency conversion, a variable attenuator interposed between the radio frequency amplifier and the mixer, an intermediate frequency amplifier disposed on the output side of the mixer, a detector and a control block. The control block generates a control signal in accordance with the intensity of the output signal of the intermeddle frequency amplifier. The attenuation amount of the variable attenuator is controlled by the control signal in a stepwise manner.
Inventors
- 👤 Hiroki Tomita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:44
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/3052; H04; H04B; H04B1/00; H04B1/06; H04B1/10; H04B1/109
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
328 words
A distortionless receiving circuit for radio receivers, comprising: radio frequency amplification means for amplifying a radio frequency reception signal and outputting it as a first signal; variable attenuation means for receiving as input said first signal, providing said first signal with a certain amount of attenuation corresponding to a control voltage and outputting it as an output signal thereof; frequency conversion means for converting said output signal of said variable attenuation means into a second signal of intermediate frequency and outputting it as an output thereof; intermediate frequency amplification means for amplifying said second signal and outputting it as a third signal; wave detection means for detecting said third signal, outputting a detected signal, and also outputting a level detection signal corresponding to an intensity of said third signal; and control means for generating said control voltage in accordance with said level detection signal; wherein said control means is adapted to generate, in a selective switching relationship, one of a first control voltage corresponding to a relatively smaller amount of attenuation in said variable attenuation means and a second control voltage corresponding to a relatively larger amount of attenuation; wherein said control voltage is switched to said second control voltage when said level detection signal increases and exceeds a first threshold, and to said first control voltage when said level detection signal decreases below a second threshold, and wherein said first threshold is larger than said second threshold; and wherein said first threshold is determined in accordance with said level detection signal obtained at a time when a receiving electric field reaches a predetermined first level under a state of said relatively smaller amount of attenuation, said second threshold is determined in accordance with said level detection signal obtained at a time when said receiving electric field has reached a predetermined second level under a state of said relatively larger amount of attenuation, and wherein said predetermined first level is larger in value than said predetermined second level.
Claim 2
Dependent Claim
328 words
A distortionless receiving circuit for radio receivers, comprising: radio frequency amplification means for amplifying a radio frequency reception signal and outputting it as a first signal; variable attenuation means for receiving as input said first signal, providing said first signal with a certain amount of attenuation corresponding to a control voltage and outputting it as an output signal thereof; frequency conversion means for converting said output signal of said variable attenuation means into a second signal of intermediate frequency and outputting it as an output thereof; intermediate frequency amplification means for amplifying said second signal and outputting it as a third signal; wave detection means for detecting said third signal, outputting a detected signal, and also outputting a level detection signal corresponding to an intensity of said third signal; and control means for generating said control voltage in accordance with said level detection signal; wherein said control means is adapted to generate, in a selective switching relationship, one of a first control voltage corresponding to a relatively smaller amount of attenuation in said variable attenuation means and a second control voltage corresponding to a relatively larger amount of attenuation; wherein said control voltage is switched to said second control voltage when said level detection signal increases and exceeds a first threshold, and to said first control voltage when said level detection signal decreases below a second threshold, and wherein said first threshold is larger than said second threshold; and wherein said first threshold is determined in accordance with said level detection signal obtained at a time when a receiving electric field reaches a predetermined first level under a state of said relatively smaller amount of attenuation, said second threshold is determined in accordance with said level detection signal obtained at a time when said receiving electric field has reached a predetermined second level under a state of said relatively larger amount of attenuation, and wherein said predetermined first level is larger in value than said predetermined second level.
Claim 3
Dependent Claim
41 words
The distortionless receiving circuit set forth in claim 1, wherein said variable attenuation means comprises a PIN diode, and said amount of attenuation is controlled by varying a bias current flowing through said PIN diode in accordance with said control voltage.
Claim 4
Dependent Claim
221 words
A distortionless receiving circuit for radio receivers, comprising: radio frequency amplification means for amplifying a radio frequency reception signal and outputting it as a first signal; variable attenuation means for receiving as input said first signal, providing said first signal with a certain amount of attenuation corresponding to a control voltage and outputting it as an output signal thereof; frequency conversion means for converting said output signal of said variable attenuation means into a second signal of intermediate frequency and outputting it as an output thereof; intermediate frequency amplification means for amplifying said second signal and outputting it as a third signal; wave detection means for detecting said third signal, outputting a detected signal, and also outputting a level detection signal corresponding to an intensity of said third signal; and control means for generating said control voltage in accordance with said level detection signal; wherein said control means comprises: threshold switching means for receiving, as input, an attenuation amount switching signal, switching the threshold according to said attenuation-amount switching signal, and outputting a threshold signal; attenuation-amount switching control means for comparing said level detection signal with said threshold signal and outputting said attenuation-amount switching signal; and a control voltage switching means for switching said control voltage according to said attenuation-amount switching signal and outputting said control voltage as the output thereof.
Claim 5
Dependent Claim
221 words
A distortionless receiving circuit for radio receivers, comprising: radio frequency amplification means for amplifying a radio frequency reception signal and outputting it as a first signal; variable attenuation means for receiving as input said first signal, providing said first signal with a certain amount of attenuation corresponding to a control voltage and outputting it as an output signal thereof; frequency conversion means for converting said output signal of said variable attenuation means into a second signal of intermediate frequency and outputting it as an output thereof; intermediate frequency amplification means for amplifying said second signal and outputting it as a third signal; wave detection means for detecting said third signal, outputting a detected signal, and also outputting a level detection signal corresponding to an intensity of said third signal; and control means for generating said control voltage in accordance with said level detection signal; wherein said control means comprises: threshold switching means for receiving, as input, an attenuation amount switching signal, switching the threshold according to said attenuation-amount switching signal, and outputting a threshold signal; attenuation-amount switching control means for comparing said level detection signal with said threshold signal and outputting said attenuation-amount switching signal; and a control voltage switching means for switching said control voltage according to said attenuation-amount switching signal and outputting said control voltage as the output thereof.
Claim 6
Dependent Claim
41 words
The distortionless receiving circuit set forth in claim 3, wherein said variable attenuation means comprises a PIN diode, and said amount of attenuation is controlled by varying a bias current flowing through said PIN diode in accordance with said control voltage.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-02-11 | 2000-08-12 | 2001-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-02-11 | 2004-08-12 | 2005-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-02-11 | 2008-08-12 | 2009-02-11 | $7700.00 | Window Closed / Lapsed |