GB2294830A - Frequency synthesizer - Google Patents
Frequency synthesizer Download PDFInfo
- Publication number
- GB2294830A GB2294830A GB9525281A GB9525281A GB2294830A GB 2294830 A GB2294830 A GB 2294830A GB 9525281 A GB9525281 A GB 9525281A GB 9525281 A GB9525281 A GB 9525281A GB 2294830 A GB2294830 A GB 2294830A
- Authority
- GB
- United Kingdom
- Prior art keywords
- frequency
- control voltage
- capacitor
- signal
- oscillated
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
- H03L7/16—Indirect frequency synthesis, i.e. generating a desired one of a number of predetermined frequencies using a frequency- or phase-locked loop
- H03L7/18—Indirect frequency synthesis, i.e. generating a desired one of a number of predetermined frequencies using a frequency- or phase-locked loop using a frequency divider or counter in the loop
- H03L7/183—Indirect frequency synthesis, i.e. generating a desired one of a number of predetermined frequencies using a frequency- or phase-locked loop using a frequency divider or counter in the loop a time difference being used for locking the loop, the counter counting between fixed numbers or the frequency divider dividing by a fixed number
- H03L7/187—Indirect frequency synthesis, i.e. generating a desired one of a number of predetermined frequencies using a frequency- or phase-locked loop using a frequency divider or counter in the loop a time difference being used for locking the loop, the counter counting between fixed numbers or the frequency divider dividing by a fixed number using means for coarse tuning the voltage controlled oscillator of the loop
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
- H03L7/08—Details of the phase-locked loop
- H03L7/099—Details of the phase-locked loop concerning mainly the controlled oscillator of the loop
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
- H03L7/08—Details of the phase-locked loop
- H03L7/10—Details of the phase-locked loop for assuring initial synchronisation or for broadening the capture range
- H03L7/101—Details of the phase-locked loop for assuring initial synchronisation or for broadening the capture range using an additional control signal to the controlled loop oscillator derived from a signal generated in the loop
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03C—MODULATION
- H03C3/00—Angle modulation
- H03C3/02—Details
- H03C3/09—Modifications of modulator for regulating the mean frequency
- H03C3/0908—Modifications of modulator for regulating the mean frequency using a phase locked loop
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L2207/00—Indexing scheme relating to automatic control of frequency or phase and to synchronisation
- H03L2207/06—Phase locked loops with a controlled oscillator having at least two frequency control terminals
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
- H03L7/08—Details of the phase-locked loop
- H03L7/10—Details of the phase-locked loop for assuring initial synchronisation or for broadening the capture range
Abstract
In a frequency synthesizer, a desired range of frequency variations is split into two or more sub-ranges f1-f4, f3-f2 so as to operate with a smaller slope of the control voltage vs oscillator frequency characteristic curve in each sub-range than that obtainable with operation in a single range f1-f2. The frequency synthesizer (fig. 3 not shown) comprises a phase lock loop including a voltage controlled oscillator including a voltage controlled capacitance varied in a continuous manner by the applied control voltage. Further capacitor(s) connected to the controlled capacitance element is selectively switched into or out of the oscillator circuit to determine the sub-ranges. Phase noise in the output signal due to a large modulation sensitivity i.e. the slope of the controlled oscillator characteristics are therby reduced. The frequency synthesizer is usable in a communication device using digital modulation such as QPSK or MSK. <IMAGE>
Description
Frequency synthesizer
BACKGROUND OP TRE INVENTION
Field of the Invention
The present invention relates to a frequency synthesizer and, more particularly, to a frequency synthesizer for use in a radio communication using digital modulation and deniodulation.
Description of the Related Art
Recently, the frequency synthesizer which is capable of oscillating a wide frequency band is requested in a wide band radio device.
Since the oscillation frequency of a voltage control oscillator (VCO) of the conventional frequency synthesizer has a one to one correspondence to the control voltage, it is necessary, in order to make the oscillation frequency band wider, to make an inclination of the control voltage-oscillation frequency characteristics curve, that is, a modulation sensitivity, larger so that the oscillation frequency is changed largely with small change of the control voltage.
In the abcve-identified frequency synthesizer, however, since the modulation sensitivity is large, noise such as battery noise, switching noise, noise of a phase detector and so on from a control voltage line of the VCO is apt to appear in an output of the VCo as phase noise.As a result, the conventional frequency synthesizer suffers from a disadvantage for a radio device using a digital modulation such as quaternary phase-shift keying (QPSK) or minimum shift keying (MSK)- S:MKARY oY TEE INVENTION
It is therefore an object of the present invention to provide a frequency synthesizer capable of reducing the phase noise of the output of the VCO due to noise from the control line of a VCC while maintaining a wide frequency band.
In our eo-pending UK patent application no. 9416381.3, a frequency synthesizer includes a voltage controlled oscillator for oscillating at a variable frequency by changing a reactance component thereof in response to a control voltage applied thereto and reactance changing means for changing a reactance component of the voltage controlled oscillator separately from the reactance change caused by the control voltage.
In our co-pending Us patent application no. 9416381.3, another frequency synthesizer includes a means for oscillating a first frequency signal having a first continuous control voltageoscillated frequency characteristic curve within a first frequency range in response to a selected control voltage variation, said first frequency range being between a first frequency and a second frequency greater than said first frequency, and a means for oscillating a second frequency signal having a second continuous control voltage-oscillated frequency characteristic curve within a second frequency range different from said first frequency range in response to said selected control voltage variation, said second frequency range being between a third frequency and a fourth frequency greater than said third frequency, whereby, there is produced control voltage-oscillated frequency characteristic curves each having an inclination less than the inclination of a third frequency signal having a continuous control voltage-oscillated frequency characteristic curve between said first and fourth frequency to thereby reduce output phase noise of said frequency synthesizer.
The frequency synthesizer oscillates over a wide band frequency even if oscillation frequency change due to change of the control voltage is small by changing the capacitance component of the voltage controlled oscillator by means of the capacitance changing means.
According to a first aspect of the present invention, a frequency synthesizer for generating a frequency signal variable between two frequencies comprises:
first means for oscillating a first frequency signal having a first continuous control voltage-oscillated frequency characteristic curve within a first frequency range in response to a selected control voltage variation, said first frequency range being between a first frequency and a second frequency greater than said first frequency; and
second means for oscillating a second frequency signal having a second continuous control voltage-oscillated frequency characteristic curve within a second frequency range different from said first frequency range in response to said selected control voltage variation, said second frequency range being between a third frequency and a forth frequency greater than said third frequency;
whereby there are produced control voltage-oscillated frequency characteristic curves each having an inclination less than the inclination of a third frequency signal having a continuous control voltage-oscillated frequency characteristic curve between said first and fourth frequency to thereby reduce output phase noise of said frequency synthesizer.
A second aspect of the present invention provides a method for controlling a frequency synthesizer for generating a frequency signal variable between two frequencies, the method comprising the steps of:
oscillating a first frequency signal having a first continuous control voltageoscillated frequency characteristic curve within a first frequency range in response to a selected control voltage variation, said first frequency range being between a first frequency and a second frequency greater than said first frequency; and
oscillating a second frequency signal having a second continuous control voltage-oscillated frequency characteristic curve within a second frequency range different from said first frequency range in response to said selected control voltage variation, said second frequency range being between a third frequency and a fourth frequency greater than said third frequency, whereby, there are produced control voltage-oscillated frequency characteristic curves each having an inclination less than the inclination of a third frequency signal having a continuous control voltage-oscillated frequency characteristic curve between said first and fourth frequency to thereby reduce output phase noise of said frequency synthesizer.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of this invention will become more apparent from the following detailed description taken with the accompanying drawings in which:
Fig. 1 is a block diagram of a conventional frequency synthesizer;
Fig. 2 is a graph showing s control voltage-oscillation frequency characteristics of the VCO shown in Fig. 1;
Fig. 3 is a block diagram of a preferred embodiment of a frequency synthesizer according to the present invention; and
Fig. 4 is a graph showing a control voltage-oscillation frequency characteristics of the VCO shown in Fig. 3.
In the drawings, the same reference numerals denote the same structural elements.
DESCRIPTION OF THE PREFERRED EMBODIMENT
First, to facilitate an understanding of the present invention, a conventional frequency synthesizer will be described with reference to Figs. 1 and 2.
In Fig. 1, a reference oscillator 10 in a frequency synthesizer 100 produces a reference signal. A frequency divider (1/N) 12 divides the frequency of a signal from a buffer amplifier 14 by the frequency dividing number N determined by a controller 16 on the basis of a required frequency. A phase detector (P.D.) 18 compares, in phase, the signal from the reference oscillator 10 with the signal from the frequency divider 12 and outputs a result of comparison. A charge pump 20 converts an amount of advance/delay of phase into a voltage on the basis of the output signal of the phase detector 18. A lowpass filter (LPF) 22 removes a.c. components of the voltage from the charge pump 20.A voltage controller oscillator (VCO) 24 produces a signal having a frequency corresponding to a control voltage from the LPF 22 through an input terminal 30 and supplies the signal from an output terminal 32 to buffer amplifiers 14 and 26 for amplifying the signal from the VCo 24. A signal from the buffer amplifier 26 is supplied from an output terminal 28 of the frequency synthesizer loO.
The VCO 24 consists of a variable capacitance diode 202, a capacitor 204 and an oscillator 206. A capacitance of the variable capacitance diode 202 is changed correspondingly to the control voltage applied to the input terminal 30 to thereby change the oscillation frequency.
Fig. 2 is a graph showing a control voltage-oscillation frequency characteristics of the VCo 24 shown in Fig. 1.
In Fig. 2, the control voltage applied to the terminal 30 is put on an abscissa and the oscillation frequency of the signal output from the output terminal 32 is put on an ordinate. As shown in Fig. 2, when the control voltage is changed from V1 to
V2, the oscillation frequency is changed from fl to fz.
As mentioned above, however, since the modulation sensitivity is large, noise such as battery noise, switching noise of the charge pump, or noise of the phase detector from the control voltage line of the VCO influences the output of the VCO as phase noise.
Now there will be described in detail preferred embodiments of the present invention with reference to Figs. 3 and 4.
Fig. 3 is a block diagram schematically showing a preferred embodiment of a frequency synthesizer according to the present invention. In Fig. 3, the frequency synthesizer 10t consists of a reference oscillator 10, a frequency divider (1/N) 12, buffer amplifiers 14 and 26, a phase detector (P.D.) 18, a charge pump 20, a low-pass filter (LPF) 22, a controller 40 and a voltage controller oscillator (vCO) 42.
In Fig. 3, the reference oscillator 10 in the frequency synthesizer 102 produces a reference signal. The frequency divider (1JN) 12 divides frequency of a signal from the buffer amplifier 14 by the frequency dividing number N determined by the controller 40 on the basis of a required frequency. The phase detector (P.D.) 16 compares, in phase, the signal from the reference oscillator 10 with a divided signal from the frequency divider 12 and outputs a result of comparison. The charge pump 20, which operates as a converter, converts an amount of advance/delay of phase into a voltage on the basis of the output signal of the phase detector 18. The LPF 22 removes a.c.
components of the voltage from the charge pump 20. The VCO 42 produces a signal having a frequency corresponding to a control voltage from the rwF 22 through an input terminal 36 and supplies the signal from an output terminal 38 to the buffer amplifiers 14 and 26 for amplifying the signal from the VCO 42. A signal from the buffer amplifier 26 is supplied from an output terminal 34 of the frequency synthesizer 102. These functions are the same as those of the conventional frequency synthesizer shown in
Fig. 1.
The VCO 42 consists of a variable capacitance diode 402, capacitors 404 and 408, an oscillator 406 and a switch 410. The capacitor 404 and variable capacitance diode 402 construct capacitance varying means. One side of the capacitor 408 is connected to a junction between the oscillator 406 and the capacitor 404. The other side of the capacitor 408 is connected to one side of the switch 410 whose other end is connected to the ground. A capacitance of the variable capacitance diode 402 is changed correspondingly to the control voltage applied to the input terminal 36 to thereby change the oscillation frequency.
The controller 40 controls the ON-OFF of the switch 410 in the VCO 42 on the basis of the required frequency.
Fig. 4 is a graph showing a control voltage-oscillation frequency characteristics of the VCO 42 shown in Fig. 3.
In Fig. 4, the control voltage applied to the input terminal 36 is put on an abscissa and the oscillation frequency of the signal output from the output terminal 38 is put on an ordinate.
A curve (a) shows the characteristics when the switch 410 is ON and a curve (b) shows the characteristics when the switch 410 is
OFF.
When the switch 410 is turned ON through a terminal 44 correspondingly to a frequency required by the controller 40, oscillation frequency required of the VCO 42 is changed from fl to f4 in response to the change V1 to V2 of the control voltage as shown by the curve (a) in Fig. 4. When the switch 410 is turned OFF through the terminal 44 correspondingly to a frequency required by the controller 40, the oscillation frequency is changed from f3 to f2 in response to the change V1 to V2 of the control voltage as shown by the curve (b) in Fig. 4. The inclination of each curve is smaller compared with that of the conventional frequency synthesizer so as to avoid the phase noise.
That is, in this embodiment, a total capacitance component of the VCO 42 is changed in dependence on whether the switch 410 is ON or OFF so that the single frequency synthesizer has two kinds of control voltage-oscillation frequency characteristics with which the frequency band from fl to f2 is covered.
Although, in this embodiment, the capacitor 408 is connected between the oscillator 406 and the capacitor 404, the present invention is not limited to this construction, provided that the total capacitance component of the VCO 42 can be changed by
ON/OFF switching of the switch 410.
Further, although in this embodiment a single capacitor which is disconnected from the circuit when the switch is turned
OFF is provided, it is possible in the present invention to provide at least two sets of such switches and capacitors so that there are at least three kinds of control voltage-oscillation frequency characteristics provided. The larger the number of the kinds of control voltage-oscillation frequency characteristics provides the smaller the inclination of the individual control voltage-oscillation frequency characteristics.
Further, the switch 410 may be a mechanical switch or an electronic switch.
As described hereinbefore, since, according to the present invention, it is possible to set a plurality of oscillation frequencies for the same control voltage by shifting the oscillation frequency of the VCO in dependence on ON/OFF state of the switch within the VCO, it is possible to set the inclination of the control voltage-oscillation frequency characteristics curve of the VCO, that is, the modulation sensitivity, smaller compared with the conventional frequency synthesizer in which all of required frequency band is covered by a single control voltage-oscillation frequency and it is possible to reduce the possibility of phase noise in an output of the VCO caused by noise indirectly introduce from the control voltage line of the VCO.
As mentioned, according to the present invention, since it is possible to reduce phase noise of the output of the frequency synthesizer, the frequency synthesizer becomes optimal for a radio device utilizing a digital modulation such as QPSK or MSK.
Although the embodiment has been described with respect to a case in which the modification was based on a specific factor, it goes without saying that the present Invention is not restricted to tis case.
Each feature disclosed in the specification (which term includes the claims) and/or shown in the drawings may be incorporated in the invention independently of other disclosed and/or illustrated features.
The text of the abstract fiied herewith is hereby deemed to be repeated here in full as part of the specification.
Claims (7)
1. A frequency synthesizer for generating a frequency signal variable between two frequencies comprising:
first means for oscillating a first frequency signal having a first continuous control voltage-oscillated frequency characteristic curve within a first frequency range in response to a selected control voltage variation, said first frequency range being between a first frequency and a second frequency greater than said first frequency; and
second means for oscillating a second frequency signal having a second continuous control voltage-oscillated frequency characteristic curve within a second frequency range different from said first frequency range in response to said selected control voltage variation, said second frequency range being between a third frequency and a fourth frequency greater than said third frequency;
whereby there are produced control voltage-oscillated frequency characteristic curves each having an inclination less than the inclination of a third frequency signal having a continuous control voltage-oscillated frequency characteristic curve between said first and fourth frequency to thereby reduce output phase noise of said frequency synthesizer.
2. The frequency synthesizer as claimed in Claim 1, further comprising:
a voltage controlled oscillator for oscillating at said first frequency range and at said second frequency range; and
reactance changing means for changing a reactance component of said voltage controlled oscillator separately from said reactance change caused by said control voltage, said first continuous control voltage-oscillated frequency characteristic curve being produced when said reactance changing means is in a first state and said second continuous control voltage-oscillated frequency characteristic curve being produced when said reactance changing means is in a second state.
3. The frequency synthesizer as claimed in Claim 2, wherein said reactance changing means comprises:
a capacitor constituting a part of said reactance component of said voltage controlled oscillator;
a switch for connecting said capacitor constituting said part of said reactance component of said voltage controlled oscillator when it is in said first state and disconnecting said capacitor from said voltage controlled oscillator when it is in said second state; and
a switch controller for controlling said switch in said first and second states.
4. The frequency synthesizer as claimed in Claim 1, further comprising:
a voltage controlled oscillator for oscillating at said first frequency range and at said second frequency range, said voltage controlled oscillator comprising
a first capacitor;
a diode, connected to said first capacitor and a ground, for changing a capacitance therein by said control voltage;
a second capacitor;
a switch, connected to said second capacitor and the ground, for connecting said second capacitor to said first capacitor and disconnecting said second capacitor from said first capacitor corresponding to a control signal of a controller; and
a oscillator, connected to a junction of said first and second capacitors, for producing said first continuous control voltage-oscillated frequency characteristic curve when said second capacitor is connected to said first capacitor and said second continuous control voltage-oscillated frequency characteristic curve when said second capacitor is disconnected from said first capacitor.
5. The frequency synthesizer as claimed in any one of Claims 2 to 4, further comprising
a reference oscillator for oscillating a reference signal;
a frequency divider for dividing frequency of an output signal from said voltage controlled oscillator and supplying a divided signal;
a phase detector, coupled to said reference oscillator and said frequency divider, for detecting a phase difference between said reference signal and said divided signal; and
a charge pump, coupled to said phase detector, for changing said phase difference to said control voltage.
6. A method for controlling a frequency synthesizer for generating a frequency signal variable between two frequencies, the method comprising the steps of:
oscillating a first frequency signal having a first continuous control voltageoscillated frequency characteristic curve within a first frequency range in response to a selected control voltage variation, said first frequency range being between a first frequency and a second frequency greater than said first frequency; and
oscillating a second frequency signal having a second continuous control voltage-oscillated frequency characteristic curve within a second frequency range different from said first frequency range in response to said selected control voltage variation, said second frequency range being between a third frequency and a fourth frequency greater than said third frequency, whereby, there are produced control voltage-oscillated frequency characteristic curves each having an inclination less than the inclination of a third frequency signal having a continuous control voltage-oscillated frequency characteristic curve between said first and fourth frequency to thereby reduce output phase noise of said frequency synthesizer.
7. A frequency synthesizer or a method of controlling a frequency synthesizer substantially as herein described with reference to Figures 3 and 4 of the accompanying drawings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5222213A JPH0758637A (en) | 1993-08-13 | 1993-08-13 | Frequency synthesizer |
| GB9416381A GB2282285A (en) | 1993-08-13 | 1994-08-12 | VCO; Frequency synthesizers |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9525281D0 GB9525281D0 (en) | 1996-02-07 |
| GB2294830A true GB2294830A (en) | 1996-05-08 |
Family
ID=26305447
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9525281A Withdrawn GB2294830A (en) | 1993-08-13 | 1994-08-12 | Frequency synthesizer |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2294830A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19644118A1 (en) * | 1996-10-23 | 1998-01-29 | Siemens Ag | Frequency synthesiser for transmitter or receiver |
| GB2324918A (en) * | 1997-02-19 | 1998-11-04 | Motorola Inc | Voltage controlled oscillators |
| GB2337382A (en) * | 1998-05-16 | 1999-11-17 | Motorola Ltd | Voltage controlled oscillators |
| GB2445980A (en) * | 2007-01-26 | 2008-07-30 | Motorola Inc | Calibration method for a synthesizer-based signal generator |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2303758C (en) | 1999-04-06 | 2004-01-06 | Micromass Limited | Improved methods of identifying peptides and proteins by mass spectrometry |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2120478A (en) * | 1982-04-22 | 1983-11-30 | Standard Telephones Cables Ltd | Voltage controlled oscillator |
| GB2216352A (en) * | 1988-02-26 | 1989-10-04 | Toshiba Kk | Tuning arrangements |
-
1994
- 1994-08-12 GB GB9525281A patent/GB2294830A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2120478A (en) * | 1982-04-22 | 1983-11-30 | Standard Telephones Cables Ltd | Voltage controlled oscillator |
| GB2216352A (en) * | 1988-02-26 | 1989-10-04 | Toshiba Kk | Tuning arrangements |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19644118A1 (en) * | 1996-10-23 | 1998-01-29 | Siemens Ag | Frequency synthesiser for transmitter or receiver |
| DE19644118C2 (en) * | 1996-10-23 | 2003-10-23 | Siemens Ag | frequency synthesizer |
| GB2324918A (en) * | 1997-02-19 | 1998-11-04 | Motorola Inc | Voltage controlled oscillators |
| GB2324918B (en) * | 1997-02-19 | 2001-04-04 | Motorola Inc | Method and apparatus for transmitting radio frequency signals |
| GB2337382A (en) * | 1998-05-16 | 1999-11-17 | Motorola Ltd | Voltage controlled oscillators |
| GB2337382B (en) * | 1998-05-16 | 2000-12-13 | Motorola Ltd | Voltage controlled oscillator |
| GB2445980A (en) * | 2007-01-26 | 2008-07-30 | Motorola Inc | Calibration method for a synthesizer-based signal generator |
| GB2445980B (en) * | 2007-01-26 | 2009-04-22 | Motorola Inc | Signal generator apparatus and method of calibration therefor |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9525281D0 (en) | 1996-02-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |