US3825855A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Frequency synthesizer with coarse stairstep frequency control and fine phase control
Assignee: US Philips Corp
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Filing: 1973-02-06
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Granted: 1974-07-23
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Expires: 1993-02-06
Abstract
Abstract The output frequency of a voltage controlled oscillator is phase and frequency locked to the frequency of a reference source through a frequency converter. The frequency converter divides the voltage controlled oscillator frequency by an adjustable division ratio and applies the divided frequency to both a phase comparator and a frequency discriminator. A coarse frequency control unit applies an output of the frequency discriminator to the voltage controlled oscillator as a stepwise adjustable coarse frequency control signal. The phase comparator output provides a fine control signal to the voltage control oscillator. In response to an adjustment of the frequency converter to a new division ratio a two position switch sets the counting direction of an up-down counter in the coarse frequency control unit in accordance with the sense of the change in division ratio. In response to a change in the output frequency of the frequency converter the frequency discriminator provides an output pulse that initiates a timing sequence in a switching circuit. The switching circuit in response to the output pulse of the frequency discriminator first disconnects the phase comparator from the frequency converter for a predetermined time period, then disconnects the frequency discriminator from the coarse frequency control unit and reconnects the frequency converter to the phase comparator for a second predetermined time period, after which the phase and frequency adjusting circuits are restored.
Inventors
- 👤 J Basset
- 👤 P Heins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:42
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/16; H03L7/18; H03L7/183; H03L7/187; H03L7/189; H03L7/08; H03L7/10; H03L7/113; H03L7/12
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
372 words
A frequency synthesizer comprising a voltage-controlled oscillator (VCO), a frequency converter connected to the output of said oscillator and being adjustable in accordance with the desired frequency, a reference frequency source, a coarse frequency control unit connected to a control input of the oscillator and adapted to vary the oscillator tuning frequency throughout its tuning range, a frequency discriminator for producing an output signal dependent on the frequency difference between the output frequency of the frequency converter and a reference frequency supplied by the reference source, means for applying said output signal as a switch-on signal to said coarse frequency control unit, and a fine frequency control unit in the form of a phase comparator for producing a control voltage dependent on the phase difference between the output frequency of the frequency converter and the reference frequency supplied by the reference source, and means for applying said control voltage to the input of the oscillator to lock said oscillator at the desired frequency, characterized in that said coarse frequency control unit is adapted for supplying a control voltage which increases or decreases stepwise with time dependent on the position of a twoposition switch which in case of variation of the adjustment of the frequency converter is set to the one or the other position in accordance with the sense of direction of the frequency variation brought about by the adjustment, the synthesizer furthermore comprising a switching circuit including a timing circuit, said switching circuit in the rest condition connecting the output of the frequency converter to an input of the phase comparator and also the output of the frequency discriminator to an input of said coarse frequency control unit, output pulses from the frequency discriminator bringing said switching circuit from its rest condition to the operating condition in which conditioN the switching circuit successively occupies a first and a second switching position under the control of said timing circuit, said switching circuit in a first switching position interrupting the said connection between the frequency converter and the phase comparator and in its second switching condition restoring the latter connection and interrupting the said connection between the frequency discriminator and said coarse frequency control unit, and subsequently returning automatically to the rest position.
Claim 2
Dependent Claim
372 words
A frequency synthesizer comprising a voltage-controlled oscillator (VCO), a frequency converter connected to the output of said oscillator and being adjustable in accordance with the desired frequency, a reference frequency source, a coarse frequency control unit connected to a control input of the oscillator and adapted to vary the oscillator tuning frequency throughout its tuning range, a frequency discriminator for producing an output signal dependent on the frequency difference between the output frequency of the frequency converter and a reference frequency supplied by the reference source, means for applying said output signal as a switch-on signal to said coarse frequency control unit, and a fine frequency control unit in the form of a phase comparator for producing a control voltage dependent on the phase difference between the output frequency of the frequency converter and the reference frequency supplied by the reference source, and means for applying said control voltage to the input of the oscillator to lock said oscillator at the desired frequency, characterized in that said coarse frequency control unit is adapted for supplying a control voltage which increases or decreases stepwise with time dependent on the position of a twoposition switch which in case of variation of the adjustment of the frequency converter is set to the one or the other position in accordance with the sense of direction of the frequency variation brought about by the adjustment, the synthesizer furthermore comprising a switching circuit including a timing circuit, said switching circuit in the rest condition connecting the output of the frequency converter to an input of the phase comparator and also the output of the frequency discriminator to an input of said coarse frequency control unit, output pulses from the frequency discriminator bringing said switching circuit from its rest condition to the operating condition in which conditioN the switching circuit successively occupies a first and a second switching position under the control of said timing circuit, said switching circuit in a first switching position interrupting the said connection between the frequency converter and the phase comparator and in its second switching condition restoring the latter connection and interrupting the said connection between the frequency discriminator and said coarse frequency control unit, and subsequently returning automatically to the rest position.
Claim 3
Dependent Claim
68 words
A sythesizer as claimed in claim 1, wherein the coarse frequency control unit is an up-down counter which as a function of the position of said twoposition switch is set to its up-counting or down-counting position, the contents of the counter being converted with the aid of an digital-to-analog converter into an analog control signal which is applied for coarse adjustment to a control input of the oscillator.
Claim 4
Dependent Claim
56 words
A synthesizer as claimed in claim 1 in which the tuning range of the voltage-controlled oscillator is subdivided in successive sub-ranges and in which each of these sub-ranges can be selected with the aid of a selector switch, characterized in that said selector switch is operated by an output signal from said course frequency control unit.
Claim 5
Dependent Claim
165 words
A synthesizer as claimed in claim 3, wherein said coarse frequency control unit comprises an up-down counter which is connected to the output of the frequency discriminator, to which counter a digital-to-analog converter is connected for producing a control voltage corresponding to the counter contents for the purpose of coarse tuning of the oscillator and to which counter a first and a second decoder are connected, said first decoder supplying an output pulse setting the first counter in the down-counting position when it reaches the maximum counter contents and said second decoder supplying an output pulse setting the said first counter in the up-counting position when it reaches the minimum counter contents, and a second up-down counter connected to a common output of said first and second decoders, to which counter a digital-to-analog converter is connected for supplying a selection signal which, applied to the said oscillator selector switch, switches-over to the sub-range of the oscillator determined by the counter contents of said second counter.
Claim 6
Dependent Claim
29 words
A synthesizer as claimed in claim 4, wherein said second counter is set to the up-counting or down-counting position as a function of the position of said two-position switch.
Claim 7
Dependent Claim
57 words
A synthesizer as claimed in claim 1, wherein the timing circuit forming part of said switching circuit comprises a first and a second monostable circuit, the duration of the first and second switching positions successively occurring during the operative condition of the switching circuit being determined by the time constants of said first and second monostable circuits.
Claim 8
Dependent Claim
173 words
A synthesizer as claimed in claim 6, wherein the frequency discriminators are built up from a counter having a decoder connected thereto which supplies an output signal when the counter contents are smaller than a given first value or larger than a given second different value, a discriminator input gate, a counter input gate, a counter reset gate as well as a bistable circuit and a discriminator output gate connected to the output of the discriminator input gate and the output of the decoder, the signal derived from the frequency converter being applied to an input of the discriminator input gate and to an input of the bistable circuit and through an inverter to an input of the counter reset gate, the second input of the discriminator input gate and the second input of the counter reset gate being connected to an output of the bistable circuit whose second output is connected to an input of the counter input gate, the output pulses from a reference source being applied to said second input.
Claim 9
Dependent Claim
18 words
A synthesizer as claimed in claim 1 wherein the frequency converter is constituted by a digital frequency divider.
Claim 10
Dependent Claim
35 words
A synthesizer as claimed in claim 1 adapted for use in a Simplex transceiver, wherein said two-position switch is coupled to the transmitreceive switch of the transceiver so that the two switches are operated simultaneously.
References Cited (Backward Citations)
US3611175A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-22 | 1978-01-21 | 1978-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-22 | 1982-01-21 | 1982-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-22 | 1986-01-21 | 1986-07-23 | $7700.00 | Window Closed / Lapsed |