Patent US6002923A successfully refreshed from Google Patents.
US6002923A
Expired / Lapsed
US
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Signal generation in a communications transmitter
Assignee: Telefonaktiebolaget LM Ericsson AB
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Filing: 1997-11-07
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Granted: 1999-12-14
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Expires: 2017-11-07
Abstract
Abstract A transmitter subsystem is disclosed whereby the output frequency spectrum of a DDS device, for use in the transmitter subsystem, is frequency multiplied to achieve greater frequency coverage at the RF bands. In one embodiment of the present invention, a DDS device is structured in such a way that the DDS output signal spectra can be multiplied directly for direct conversion to RF or IF bands. As such, the requirements placed on the DACs in the DDS device are lessened, because the DACs require much lower sampling frequencies than those used in the existing technology. Also, the requirements placed on the implemented bandpass filters used for image rejection in the applied upconverters are lessened, because of the larger frequency difference created between the desired output and the image frequency band. In a second embodiment of the present invention, a DDS device is also structured in such a way that multiplication of the baseband spectra can be accomplished at the IF. Consequently, in accordance with the present invention, less complex or costly DACs can be used for generating wideband signals at higher frequencies, but relatively high linearity signals can still be attained.
Inventors
- 👤 Karl-Gosta Sahlman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 14:21
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/32; H04L27/34; H04L27/36; H04L27/361; H03; H03D; H03D7/00; H03D7/18
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
95 words
A system for generating an RF signal in a communications transmitter, comprising: a DDS signal generator for generating a baseband signal, said baseband signal comprising an amplitude-modulated signal and a phase-modulated signal; a frequency multiplier coupled to a first output of said DDS signal generator for multiplying said phase-modulated signal; a frequency upconverter, coupled to said frequency multiplier, for upconverting an output of said frequency multiplier; and a combiner, coupled to said frequency upconverter and a second output of said DDS signal generator, for combining an output of said frequency upconverter with said amplitude-modulated signal.
Claim 2
Independent Claim
95 words
A system for generating an RF signal in a communications transmitter, comprising: a DDS signal generator for generating a baseband signal, said baseband signal comprising an amplitude-modulated signal and a phase-modulated signal; a frequency multiplier coupled to a first output of said DDS signal generator for multiplying said phase-modulated signal; a frequency upconverter, coupled to said frequency multiplier, for upconverting an output of said frequency multiplier; and a combiner, coupled to said frequency upconverter and a second output of said DDS signal generator, for combining an output of said frequency upconverter with said amplitude-modulated signal.
Claim 3
Dependent Claim
16 words
The system of claim 1, wherein said DDS signal generator comprises a DDS channel signal generator.
Claim 4
Dependent Claim
13 words
The system of claim 1, wherein said combiner comprises a variable gain amplifier.
Claim 5
Dependent Claim
18 words
The system of claim 1, wherein said frequency multiplier comprises a DDS-driven continuous amplitude phase-modulated phase lock loop.
Claim 6
Dependent Claim
27 words
The system of claim 1, wherein said DDS signal generator includes at least one digital to analog converter coupled to an output of a digital signal generator.
Claim 7
Dependent Claim
54 words
The system of claim 1, wherein said frequency upconverter comprises: a first bandpass filter coupled to an output of said frequency multiplier; an RF mixer coupled to an output of said bandpass filter and an output of an RF local oscillator; and a second bandpass filter coupled to an output of said RF mixer.
Claim 8
Independent Claim
97 words
A system for generating an RF signal in a communications transmitter, comprising: a DDS signal generator for generating a baseband signal, said baseband signal comprising an amplitude-modulated signal and a phase-modulated signal; a frequency upconverter, coupled to a first output of said DDS signal generator, for upconverting said phase-modulated signal to an IF signal; a frequency multiplier, coupled to said frequency upconverter, for further upconverting said IF signal; and a combiner, coupled to said frequency multiplier and a second output of said DDS signal generator, for combining an output of said frequency multiplier with said amplitude-modulated signal.
Claim 9
Independent Claim
97 words
A system for generating an RF signal in a communications transmitter, comprising: a DDS signal generator for generating a baseband signal, said baseband signal comprising an amplitude-modulated signal and a phase-modulated signal; a frequency upconverter, coupled to a first output of said DDS signal generator, for upconverting said phase-modulated signal to an IF signal; a frequency multiplier, coupled to said frequency upconverter, for further upconverting said IF signal; and a combiner, coupled to said frequency multiplier and a second output of said DDS signal generator, for combining an output of said frequency multiplier with said amplitude-modulated signal.
Claim 10
Dependent Claim
16 words
The system of claim 7, wherein said DDS signal generator comprises a DDS channel signal generator.
Claim 11
Dependent Claim
19 words
The system of claim 7, wherein said frequency multiplier comprises a DDS-driven continuous amplitude phase modulated phase lock loop.
Claim 12
Dependent Claim
27 words
The system of claim 7, wherein said DDS signal generator includes at least one digital to analog converter coupled to an output of a digital signal generator.
Claim 13
Dependent Claim
13 words
The system of claim 7, wherein said combiner comprises a variable gain amplifier.
Claim 14
Dependent Claim
77 words
An improved baseband signal generator for use in a communications transmitter, comprising: a DDS signal generator for generating a baseband signal, said baseband signal comprising a phase-modulated signal and an amplitude-modulated signal; a frequency multiplier coupled to said DDS signal generator, for multiplying said phase-modulated signal; and an analog multiplier coupled to said frequency multiplier and an amplitude-modulated output of said DDS signal generator, for multiplying an output of said frequency multiplier with said amplitude-modulated output signal.
Claim 15
Dependent Claim
77 words
An improved baseband signal generator for use in a communications transmitter, comprising: a DDS signal generator for generating a baseband signal, said baseband signal comprising a phase-modulated signal and an amplitude-modulated signal; a frequency multiplier coupled to said DDS signal generator, for multiplying said phase-modulated signal; and an analog multiplier coupled to said frequency multiplier and an amplitude-modulated output of said DDS signal generator, for multiplying an output of said frequency multiplier with said amplitude-modulated output signal.
Claim 16
Dependent Claim
19 words
The improved baseband signal generator of claim 12, wherein said DDS signal generator comprises a DDS channel signal generator.
Claim 17
Dependent Claim
21 words
The improved baseband signal generator of claim 12, wherein said frequency multiplier comprises a DDS-driven continuous amplitude phase-modulated phase lock loop.
Claim 18
Independent Claim
59 words
A method for generating an RF signal in a communications transmitter, comprising the steps of: generating a baseband signal, said baseband signal comprising an amplitude-modulated signal and a phase-modulated signal; frequency multiplying said phase modulated signal; upconverting a multiplication of said phase-modulated signal to obtain an intermediate RF signal; and combining said intermediate RF signal with said amplitude-modulated signal.
Claim 19
Independent Claim
59 words
A method for generating an RF signal in a communications transmitter, comprising the steps of: generating a baseband signal, said baseband signal comprising an amplitude-modulated signal and a phase-modulated signal; frequency multiplying said phase modulated signal; upconverting a multiplication of said phase-modulated signal to obtain an intermediate RF signal; and combining said intermediate RF signal with said amplitude-modulated signal.
Claim 20
Dependent Claim
16 words
The method of claim 15, wherein said combining step is performed by a variable gain amplifier.
Claim 21
Dependent Claim
20 words
The method of claim 15, wherein the frequency multiplying step further comprises bandpass filtering said multiplication of said phase-modulated signal.
Claim 22
Independent Claim
60 words
A method for generating an RF signal in a communications transmitter, comprising the steps of: generating a baseband signal, said baseband signal comprising an amplitude-modulated signal and a phase-modulated signal; upconverting said phase-modulated signal to generate an IF signal; frequency multiplying said IF signal to obtain an intermediate RF signal; and combining said intermediate RF signal with said amplitude-modulated signal.
Claim 23
Independent Claim
60 words
A method for generating an RF signal in a communications transmitter, comprising the steps of: generating a baseband signal, said baseband signal comprising an amplitude-modulated signal and a phase-modulated signal; upconverting said phase-modulated signal to generate an IF signal; frequency multiplying said IF signal to obtain an intermediate RF signal; and combining said intermediate RF signal with said amplitude-modulated signal.
Claim 24
Dependent Claim
16 words
The method of claim 18, wherein said combining step is performed by a variable gain amplifier.
Claim 25
Dependent Claim
18 words
The method of claim 18, wherein the frequency multiplying step further comprises bandpass filtering said intermediate RF signal.
Claim 26
Independent Claim
51 words
A method for generating a baseband signal with frequency multiplication, comprising the steps of: generating said baseband signal, said baseband signal comprising a phase-modulated signal and an amplitude-modulated signal; frequency multiplying said phase-modulated signal; and performing an analog multiplication of a frequency multiplication of said phase-modulated signal with said amplitude-modulated signal.
Claim 27
Independent Claim
51 words
A method for generating a baseband signal with frequency multiplication, comprising the steps of: generating said baseband signal, said baseband signal comprising a phase-modulated signal and an amplitude-modulated signal; frequency multiplying said phase-modulated signal; and performing an analog multiplication of a frequency multiplication of said phase-modulated signal with said amplitude-modulated signal.
Claim 28
Dependent Claim
16 words
The method of claim 21, wherein said performing step is performed by a variable gain amplifier.
Claim 29
Dependent Claim
20 words
The method of claim 21, wherein the frequency multiplying step further comprises bandpass filtering said multiplication of said phase-modulated signal.
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