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Patent US5834987A successfully refreshed from Google Patents.
US5834987A
Expired / Lapsed
US
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Frequency synthesizer systems and methods for three-point modulation with a DC response
Assignee: Ericsson Inc
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Filing: 1997-07-30
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Granted: 1998-11-10
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Expires: 2017-07-30
Abstract
Abstract A frequency synthesizer includes a controlled oscillator which is responsive to a frequency control input signal, to generate an output frequency. A programmable frequency divider is responsive to the output frequency and to a divider control input, to divide the output frequency by a first integral ratio or by a second integral ratio in response to the divider control input, to thereby produce a divided signal. A phase comparator is responsive to a reference frequency signal and to the divided signal, to compare the reference frequency signal and the divided signal, and thereby produce a first error signal. A sigma-delta modulator is responsive to a modulation input to produce the divider control input. A loop filter is responsive to the first error signal, to thereby produce the frequency control input signal. Ripple compensation signals and direct modulation signals may also be provided, to provide a three-point modulator for a frequency synthesizer. Analog and digital embodiments may also be provided.
Inventors
- 👤 Paul Wilkinson Dent
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 12:43
CPC Classifications
H; H03; H03C; H03C3/00; H03C3/02; H03C3/09; H03C3/0908; H03C3/0975; H03C3/0916; H03C3/0925; H03C3/0933; H03C3/0941; H03C3/0966; H03L; H03L7/00; H03L7/06; H03L7/16; H03L7/18; H03L7/197; H03L7/1974; H03L7/1976
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
153 words
A frequency synthesizer which generates an output frequency, comprising: a controlled oscillator which is responsive to a frequency control input signal, to generate the output frequency; a programmable frequency divider which is responsive to the output frequency and to a divider control input, to divide the output frequency by a first integral ratio or by a second integral ratio in response to the divider control input, to thereby produce a divided signal; a phase comparator which is responsive to a reference frequency signal and to the divided signal, to compare the reference frequency signal and the divided signal and thereby produce a first error signal; a sigma-delta modulator which is responsive to an analog modulation input, to produce the divider control input and a ripple compensation signal; and a loop filter which is responsive to the first error signal and to the ripple compensation signal to thereby produce the frequency control input signal.
Claim 2
Dependent Claim
153 words
A frequency synthesizer which generates an output frequency, comprising: a controlled oscillator which is responsive to a frequency control input signal, to generate the output frequency; a programmable frequency divider which is responsive to the output frequency and to a divider control input, to divide the output frequency by a first integral ratio or by a second integral ratio in response to the divider control input, to thereby produce a divided signal; a phase comparator which is responsive to a reference frequency signal and to the divided signal, to compare the reference frequency signal and the divided signal and thereby produce a first error signal; a sigma-delta modulator which is responsive to an analog modulation input, to produce the divider control input and a ripple compensation signal; and a loop filter which is responsive to the first error signal and to the ripple compensation signal to thereby produce the frequency control input signal.
Claim 3
Dependent Claim
25 words
A frequency synthesizer according to claim 1 wherein the sigma-delta modulator includes an integrator, and wherein the ripple compensation signal is produced by the integrator.
Claim 4
Dependent Claim
19 words
A frequency synthesizer according to claim 1 wherein the controlled oscillator is also responsive to the analog modulation output.
Claim 5
Dependent Claim
63 words
A frequency synthesizer according to claim 1 herein the sigma-delta modulator comprises: a comparator which compares the divider control input and the analog modulation input to produce a second error signal; an error integrator which integrates the second error signal to produce an integrated error signal; and a sampler/quantizer which samples and quantizes the second error signal to produce the divider control input.
Claim 6
Dependent Claim
25 words
A frequency synthesizer according to claim 4 further wherein the loop filter is responsive to the first error signal and to the integrated error signal.
Claim 7
Dependent Claim
163 words
A frequency synthesizer which generates an output frequency, comprising: a controlled oscillator which is responsive to a frequency control input signal, to generate the output frequency; a programmable frequency divider which is responsive to the output frequency and to a divider control input, to divide the output frequency by a first integral ratio or by a second integral ratio in response to the divider control input, to thereby produce a divided signal; a phase comparator which is responsive to a reference frequency signal and to the divided signal, to compare the reference frequency signal and the divided signal and thereby produce a first error signal; a sigma-delta modulator which is responsive to a modulation input, to produce the divider control input; a loop filter which is responsive to the first error signal to thereby produce the frequency control input signal; and a direct modulation injector which is responsive to the loop filter and to the modulation input, to produce the frequency control signal.
Claim 8
Dependent Claim
163 words
A frequency synthesizer which generates an output frequency, comprising: a controlled oscillator which is responsive to a frequency control input signal, to generate the output frequency; a programmable frequency divider which is responsive to the output frequency and to a divider control input, to divide the output frequency by a first integral ratio or by a second integral ratio in response to the divider control input, to thereby produce a divided signal; a phase comparator which is responsive to a reference frequency signal and to the divided signal, to compare the reference frequency signal and the divided signal and thereby produce a first error signal; a sigma-delta modulator which is responsive to a modulation input, to produce the divider control input; a loop filter which is responsive to the first error signal to thereby produce the frequency control input signal; and a direct modulation injector which is responsive to the loop filter and to the modulation input, to produce the frequency control signal.
Claim 9
Dependent Claim
30 words
A frequency synthesizer according to claim 6 wherein the sigma-delta modulator is a digital sigma-delta modulator which is responsive to a digital modulation input to produce the divider control input.
Claim 10
Dependent Claim
18 words
A frequency synthesizer according to claim 6 wherein the modulation input is a continuously variable analog modulation input.
Claim 11
Dependent Claim
185 words
A frequency synthesizer which generates an output frequency, comprising: a controlled oscillator which is responsive to a frequency control input signal, to generate the output frequency; a programmable frequency divider which is responsive to the output frequency and to a divider control input, to divide the output frequency by a first integral ratio or by a second integral ratio in response to the divider control input, to thereby produce a divided signal; a phase comparator which is responsive to a reference frequency signal and to the divided signal, to compare the reference frequency signal and the divided signal and thereby produce a first error signal; a sigma-delta modulator which is responsive to a modulation input, to produce the divider control input; a loop filter which is responsive to the first error signal to thereby produce the frequency control input signal; a scaler which is responsive to the ripple compensation signal; and a compensation injector which is responsive to the scaler and to the first error signal, to produce a compensated first error signal, and to provide the compensated first error signal to the loop filter.
Claim 12
Dependent Claim
185 words
A frequency synthesizer which generates an output frequency, comprising: a controlled oscillator which is responsive to a frequency control input signal, to generate the output frequency; a programmable frequency divider which is responsive to the output frequency and to a divider control input, to divide the output frequency by a first integral ratio or by a second integral ratio in response to the divider control input, to thereby produce a divided signal; a phase comparator which is responsive to a reference frequency signal and to the divided signal, to compare the reference frequency signal and the divided signal and thereby produce a first error signal; a sigma-delta modulator which is responsive to a modulation input, to produce the divider control input; a loop filter which is responsive to the first error signal to thereby produce the frequency control input signal; a scaler which is responsive to the ripple compensation signal; and a compensation injector which is responsive to the scaler and to the first error signal, to produce a compensated first error signal, and to provide the compensated first error signal to the loop filter.
Claim 13
Dependent Claim
166 words
A frequency synthesizer which generates an output frequency, comprising: a controlled oscillator which generates the output frequency; a programmable frequency divider which divides the output frequency by a first or second integral ratio to thereby produce a divided signal; a phase comparator which is responsive to a reference signal and to the divided signal, to compare the reference frequency signal and the divided signal; and a three point modulator which is responsive to a modulation signal, and generates a sampled and quantized approximation of the modulation signal and provides the sampled and quantized approximation to the frequency divider to control the first or second integral ratio, which generates a phase error compensation waveform from the modulation signal and combines the phase error compensation waveform and the output of the phase comparator to produce a first control signal, and which combines the modulation signal and the first control signal to produce a second control signal which is applied to the controlled oscillator to generate the output frequency.
Claim 14
Dependent Claim
166 words
A frequency synthesizer which generates an output frequency, comprising: a controlled oscillator which generates the output frequency; a programmable frequency divider which divides the output frequency by a first or second integral ratio to thereby produce a divided signal; a phase comparator which is responsive to a reference signal and to the divided signal, to compare the reference frequency signal and the divided signal; and a three point modulator which is responsive to a modulation signal, and generates a sampled and quantized approximation of the modulation signal and provides the sampled and quantized approximation to the frequency divider to control the first or second integral ratio, which generates a phase error compensation waveform from the modulation signal and combines the phase error compensation waveform and the output of the phase comparator to produce a first control signal, and which combines the modulation signal and the first control signal to produce a second control signal which is applied to the controlled oscillator to generate the output frequency.
Claim 15
Dependent Claim
16 words
A frequency synthesizer according to claim 10 wherein the three point modulator comprises a sigma-delta modulator.
Claim 16
Dependent Claim
16 words
A frequency synthesizer according to claim 11 wherein the sigma-delta modulator is a digital sigma-delta modulator.
Claim 17
Dependent Claim
148 words
A modulator which modulates a frequency synthesizer with a digital data stream to produce a modulated output signal at a carrier frequency, the frequency synthesizer including a controlled oscillator, a loop filter, a phase comparator and a programmable frequency divider, the modulator comprising: an input register which stores a predetermined portion of the digital data stream; a counter which increments at a multiple of the symbol rate of the digital data stream; and a memory including a first address input which is connected to the input register and a second address input which is connected to the counter, the memory storing predetermined bit sequences; the memory providing at least one bit as a function of the first address input and the second address input, to produce a control signal for the programmable frequency divider; wherein the programmable frequency divider is connected to the counter to clock the counter.
Claim 18
Dependent Claim
148 words
A modulator which modulates a frequency synthesizer with a digital data stream to produce a modulated output signal at a carrier frequency, the frequency synthesizer including a controlled oscillator, a loop filter, a phase comparator and a programmable frequency divider, the modulator comprising: an input register which stores a predetermined portion of the digital data stream; a counter which increments at a multiple of the symbol rate of the digital data stream; and a memory including a first address input which is connected to the input register and a second address input which is connected to the counter, the memory storing predetermined bit sequences; the memory providing at least one bit as a function of the first address input and the second address input, to produce a control signal for the programmable frequency divider; wherein the programmable frequency divider is connected to the counter to clock the counter.
Claim 19
Dependent Claim
38 words
A modulator according to claim 13 wherein the memory includes a third address input which is connected to channel frequency control bits, the at least one bit being a function of the first, second and third address inputs.
Claim 20
Dependent Claim
16 words
A modulator according to claim 13 wherein the control signal comprises a main sigma-delta data stream.
Claim 21
Dependent Claim
38 words
A modulator according to claim 15 wherein the memory also provides a ripple compensation sigma-delta data stream as a function of the first address input and the second address input, and which is applied to the loop filter.
Claim 22
Dependent Claim
38 words
A modulator according to claim 16 wherein the memory also provides a direct modulation sigma-delta data stream as a function of the first address input and the second address input, and which is applied to the controlled oscillator.
Claim 23
Dependent Claim
120 words
A modulator which modulates a frequency synthesizer with a digital data stream to produce a modulated output signal at a carrier frequency, the frequency synthesizer including a controlled oscillator, a loop filter and a phase comparator, the modulator comprising: a digital waveform generator which is responsive to the digital data stream to generate numerical samples which represent the modulation waveform; a digital sigma-delta converter which is responsive to the digital waveform generator to convert the numerical samples into a stream of sigma-delta modulation symbols at a symbol rate which is determined by a clock signal; and a programmable frequency divider which divides the controlled oscillator output by an integer determined by the sigma-delta modulation symbols, to produce the clock signal.
Claim 24
Dependent Claim
120 words
A modulator which modulates a frequency synthesizer with a digital data stream to produce a modulated output signal at a carrier frequency, the frequency synthesizer including a controlled oscillator, a loop filter and a phase comparator, the modulator comprising: a digital waveform generator which is responsive to the digital data stream to generate numerical samples which represent the modulation waveform; a digital sigma-delta converter which is responsive to the digital waveform generator to convert the numerical samples into a stream of sigma-delta modulation symbols at a symbol rate which is determined by a clock signal; and a programmable frequency divider which divides the controlled oscillator output by an integer determined by the sigma-delta modulation symbols, to produce the clock signal.
Claim 25
Dependent Claim
34 words
A modulator according to claim 18 wherein the digital sigma-delta converter comprises a digital comparator which is responsive to the digital waveform generator, and a digital accumulator which is responsive to the digital comparator.
Claim 26
Dependent Claim
24 words
A modulator according to claim 18 wherein the digital sigma-delta converter also produces a ripple compensation signal which is applied to the loop filter.
Claim 27
Dependent Claim
19 words
A modulator according to claim 18 wherein the digital sigma-delta converter is also responsive to channel frequency control bits.
Claim 28
Dependent Claim
124 words
A modulator which modulates a frequency synthesizer with a digital data stream to produce a modulated output signal at a carrier frequency, the frequency synthesizer including a controlled oscillator, a loop filter, a phase comparator and a programmable frequency divider, the modulator comprising: a digital waveform generator which is responsive to the digital data stream to generate numerical samples which represent the modulation waveform; and a digital sigma-delta converter which is responsive to the digital waveform generator to produce a control signal for the programmable frequency divider; wherein the digital sigma-delta converter also produces a ripple compensation signal which is applied to the loop filter; and wherein the digital sigma-delta converter also produces a direct compensation signal which is applied to the controlled oscillator.
Claim 29
Dependent Claim
124 words
A modulator which modulates a frequency synthesizer with a digital data stream to produce a modulated output signal at a carrier frequency, the frequency synthesizer including a controlled oscillator, a loop filter, a phase comparator and a programmable frequency divider, the modulator comprising: a digital waveform generator which is responsive to the digital data stream to generate numerical samples which represent the modulation waveform; and a digital sigma-delta converter which is responsive to the digital waveform generator to produce a control signal for the programmable frequency divider; wherein the digital sigma-delta converter also produces a ripple compensation signal which is applied to the loop filter; and wherein the digital sigma-delta converter also produces a direct compensation signal which is applied to the controlled oscillator.
Claim 30
Dependent Claim
134 words
A frequency synthesizing method for generating a modulated output signal at a desired frequency, comprising the steps of: generating the modulated output signal using a controlled oscillator having a frequency control signal input; sigma-delta converting a modulation input to produce a second error signal and a stream of sigma-delta modulation symbols at a symbol rate determined by a clock signal; dividing the modulated output signal by an integer ratio selected from at least a first integer ratio or a second integer ratio in response to the symbols and a frequency control input, to produce the clock signal; comparing the clock signal with a reference frequency signal to thereby produce a first error signal; and loop filtering the first and second error signals to thereby produce the frequency control signal input to the controlled oscillator.
Claim 31
Dependent Claim
134 words
A frequency synthesizing method for generating a modulated output signal at a desired frequency, comprising the steps of: generating the modulated output signal using a controlled oscillator having a frequency control signal input; sigma-delta converting a modulation input to produce a second error signal and a stream of sigma-delta modulation symbols at a symbol rate determined by a clock signal; dividing the modulated output signal by an integer ratio selected from at least a first integer ratio or a second integer ratio in response to the symbols and a frequency control input, to produce the clock signal; comparing the clock signal with a reference frequency signal to thereby produce a first error signal; and loop filtering the first and second error signals to thereby produce the frequency control signal input to the controlled oscillator.
Claim 32
Dependent Claim
26 words
A frequency synthesizing method according to claim 23 wherein the sigma-delta converter includes an integrator and wherein the second error signal is produced by the integrator.
Claim 33
Dependent Claim
26 words
A frequency synthesizing method according to claim 23, wherein the at least a first and a second integer ratios are changed according to the desired frequency.
Claim 34
Dependent Claim
57 words
A frequency synthesizing method according to claim 23 wherein the sigma-delta modulating step comprises the steps of: comparing the divider control input and the modulation input to produce the second error signal; integrating the second error signal to produce an integrated error signal; and sampling and quantizing the second error signal to produce the divider control signal.
Claim 35
Dependent Claim
19 words
A frequency synthesizing method according to claim 23 wherein the modulation input is a continuously variable analog modulation input.
Claim 36
Dependent Claim
151 words
A modulating method for a frequency synthesizer which generates an output frequency, the frequency synthesizer comprising a controlled oscillator which generates the output frequency; a programmable frequency divider which divides the output frequency to thereby produce a divided signal; and a phase comparator which is responsive to a reference signal and to the divided signal, to compare the reference frequency signal and the divided signal; the modulating method comprising the steps of: generating a sampled and quantized approximation of the modulation signal and providing the sampled and quantized approximation to the frequency divider; generating a phase error compensation waveform from the modulation signal and combining the phase error compensation waveform and the output of the phase comparator to produce a first control signal; and combining the modulation signal and the first control signal to produce a second control signal which is applied to the controlled oscillator to generate the output frequency.
Claim 37
Dependent Claim
151 words
A modulating method for a frequency synthesizer which generates an output frequency, the frequency synthesizer comprising a controlled oscillator which generates the output frequency; a programmable frequency divider which divides the output frequency to thereby produce a divided signal; and a phase comparator which is responsive to a reference signal and to the divided signal, to compare the reference frequency signal and the divided signal; the modulating method comprising the steps of: generating a sampled and quantized approximation of the modulation signal and providing the sampled and quantized approximation to the frequency divider; generating a phase error compensation waveform from the modulation signal and combining the phase error compensation waveform and the output of the phase comparator to produce a first control signal; and combining the modulation signal and the first control signal to produce a second control signal which is applied to the controlled oscillator to generate the output frequency.
Claim 38
Dependent Claim
115 words
A modulating method for modulating a frequency synthesizer with a digital data stream to produce a modulated output signal at a carrier frequency, the frequency synthesizer including a controlled oscillator, a loop filter, a phase comparator and a programmable frequency divider, the modulating method comprising the steps of: generating numerical samples from the digital data stream, which represent the modulated output signal; and digital sigma-delta converting the numerical samples to produce a control signal for the programmable frequency divider, wherein the digital sigma-delta converting step further comprises the steps of: producing a ripple compensation signal which is applied to the loop filter; and producing a direct compensation signal which is applied to the controlled oscillator.
Claim 39
Dependent Claim
115 words
A modulating method for modulating a frequency synthesizer with a digital data stream to produce a modulated output signal at a carrier frequency, the frequency synthesizer including a controlled oscillator, a loop filter, a phase comparator and a programmable frequency divider, the modulating method comprising the steps of: generating numerical samples from the digital data stream, which represent the modulated output signal; and digital sigma-delta converting the numerical samples to produce a control signal for the programmable frequency divider, wherein the digital sigma-delta converting step further comprises the steps of: producing a ripple compensation signal which is applied to the loop filter; and producing a direct compensation signal which is applied to the controlled oscillator.
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