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EP0538870A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Digital modulator with digital power control circuit

Assignee: NEC Corp
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Filing: 1992-10-22
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Granted: —
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Expires: 2012-10-22
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Abstract

Abstract A digital modulator comprises a power control circuit for producing a digital power control signal, first and second digital multipliers for multiplying digital signals having orthogonal phase relationships with the digital power control signal, and first and second digital-to-analog (D/A) converters for converting digital output signals from the first and second multipliers into analog signals. First and second low-pass filters are connected to outputs of the D/A converters, respectively, to filter out high frequency components. An orthogonal modulator is provided for mixing orthogonal phase carriers with the outputs of the first and second low-pass filters to produce first and second orthogonally modulated signals and combining the modulated signals to produce a transmit signal, which is amplified for transmission.

Inventors

  • 👤 Takayuki Shibata

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-27 15:50
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/18; H04L27/20; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/3036; H03G3/3042; H04L27/2032; H04L27/2053; H04L27/206; H04L27/2067; H04L27/2071

Claims Analysis

Total Claims: 3
Claim 1
Independent Claim 124 words
A digital modulator comprising: a power control circuit (12) for producing a digital power control signal; first and second digital multipliers (4A, 4B) for multiplying digital signals having orthogonal phase relationships with said digital power control signal; first and second digital-to-analog (D/A) converters (5A, 5B) for converting digital output signals from said first and second multipliers into analog signals; first and second low-pass filters (6A, 6B) connected to outputs of said D/A converters, respectively; orthogonal modulator means (7A, 7B, 8, 9, 11) for mixing orthogonal phase carriers with output signals from said first and second low-pass filters to produce first and second orthogonally modulated signals and combining the modulated signals to produce a transmit signal; and amplifier means (10) for amplifying the transmit signal.
Claim 2
Dependent Claim 125 words
A digital modulator as claimed in claim 1, wherein said digital power control circuit (12) comprises: a delay circuit (16) for delaying an input digital power control signal for a prescribed interval to produce a delayed version of the digital power control signal; and a memory (17) storing digital values in locations addressable in response to a non-delayed version of said input digital power control signal and the delayed version of said digital power control signal to produce a digital multiplying signal which varies gradually during said prescribed interval when there is a difference in magnitude between said delayed and non-delayed versions of the power control signal, said digital multiplying signal being applied to said digital multipliers (4A, 4B) as said digital power control signal.
Claim 3
Dependent Claim 90 words
A digital modulator as claimed in claim 2, wherein the digital values stored in said memory (17) are derived by subtractor means (20) for detecting a difference between said delayed and non-delayed versions of the power control signal, means (21) for generating a sequence of nonlinearly varying digital values during said prescribed interval in response to said detected difference, and adder means (22) for summing the delayed version of said power control signal with the sequence of nonlinearly varying digital values to produce said digital values stored in said memory.

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