US20010035775A1 - Adjusting untrimmed VCO during operation of the oscillator - Google Patents
Adjusting untrimmed VCO during operation of the oscillator Download PDFInfo
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- US20010035775A1 US20010035775A1 US09/887,912 US88791201A US2001035775A1 US 20010035775 A1 US20010035775 A1 US 20010035775A1 US 88791201 A US88791201 A US 88791201A US 2001035775 A1 US2001035775 A1 US 2001035775A1
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- 238000000034 method Methods 0.000 claims abstract description 10
- 239000013078 crystal Substances 0.000 claims abstract description 4
- 239000003990 capacitor Substances 0.000 claims description 10
- 230000001413 cellular effect Effects 0.000 claims description 10
- 230000015654 memory Effects 0.000 claims description 7
- 230000003321 amplification Effects 0.000 claims 1
- 238000004590 computer program Methods 0.000 claims 1
- 238000003199 nucleic acid amplification method Methods 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 6
- 238000004891 communication Methods 0.000 description 9
- 238000010586 diagram Methods 0.000 description 7
- 238000009966 trimming Methods 0.000 description 3
- 230000000903 blocking effect Effects 0.000 description 2
- 238000011045 prefiltration Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 230000006870 function Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000005236 sound signal Effects 0.000 description 1
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Classifications
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- 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
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
- H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
- H03B5/1203—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device the amplifier being a single transistor
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
- H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
- H03B5/1231—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device the amplifier comprising one or more bipolar transistors
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
- H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
- H03B5/1237—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device comprising means for varying the frequency of the generator
- H03B5/124—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device comprising means for varying the frequency of the generator the means comprising a voltage dependent capacitance
- H03B5/1243—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device comprising means for varying the frequency of the generator the means comprising a voltage dependent capacitance the means comprising voltage variable capacitance diodes
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03C—MODULATION
- H03C1/00—Amplitude modulation
- H03C1/36—Amplitude modulation by means of semiconductor device having at least three electrodes
-
- 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
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J2200/00—Indexing scheme relating to tuning resonant circuits and selecting resonant circuits
- H03J2200/29—Self-calibration of a receiver
-
- 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
Abstract
A frequency oscillator tuning process at the manufacturing stage is replaced with an adjustment of a resonant circuit in the frequency oscillator during an operation of the oscillator. The adjustment utilizes a crystal oscillator, a frequency oscillator such as a voltage-controlled oscillator (VCO), and a trimmer in a phase-locked loop configuration to determine a correction voltage required for an untrimmed VCO to operate at a nominally specified frequency by adjusting an input tuning voltage for a resonant circuit.
Description
- This invention relates to voltage-controlled oscillators.
- A frequency oscillator, such as a voltage-controlled oscillator (VCO), is an important component in telecommunication and other devices. The VCO is used as a local oscillator for up/down converters in radio systems, and as a modem oscillator in virtually all wireless and cellular systems.
- The VCO is often manually adjusted during manufacturing to trim the center frequency of the resonator. However, this trimming or tuning process occupies a significant portion of the cost of a VCO. Therefore, it is advantageous to design a system in which the tuning process during manufacturing can be eliminated.
- A frequency oscillator tuning process at the manufacturing stage is replaced with an adjustment of a resonant circuit in the frequency oscillator during the operation of the oscillator.
- The technique utilizes a crystal oscillator, a frequency oscillator such as a voltage-controlled oscillator (VCO), and a trimmer in a phase-locked loop configuration to determine a correction voltage required for an untrimmed VCO to operate at a nominally specified frequency by adjusting an input tuning voltage for a resonant circuit.
- The trimmer for adjusting an operating frequency of the VCO includes a storage element having a set of calibrated data corresponding to a set of input signals. The trimmer also includes a controller configured to utilize the set of calibrated data to provide an appropriate tuning signal for tuning the VCO to a nominally specified output frequency. In some embodiments, the trimmer involves searching a look-up table for a calibrated data corresponding to an input signal.
- The frequency oscillator having the trimmer further includes
- a resonant circuit configured to receive the tuning signal from the trimmer and generate a wave energy signal of a particular frequency corresponding to the tuning signal, such that the particular frequency is substantially close to a nominally specified output frequency of the oscillator.
- Different aspects of the disclosure will be described in reference to the accompanying drawings wherein:
- FIG. 1 is a schematic diagram a frequency oscillator such as a voltage-controlled oscillator;
- FIG. 2 is a block diagram of an input voltage tuner;
- FIG. 3 is a flow diagram of an oscillator tuning process;
- FIG. 4 is a block diagram of a frequency synthesizer;
- FIG. 5 is an alternative embodiment of the frequency oscillator shown in FIG. 1;
- FIG. 6 is a block diagram of a communication device;
- FIG. 7 is an exploded view of a cellular telephone system; and
- FIG. 8 is a front view of a paging device.
- One embodiment of a
frequency oscillator 100, such as a voltage-controlled oscillator (VCO), is shown in FIG. 1. The output frequency of theVCO 100 is controlled by the impedance at thebase 110 of the transistor presented by aresonant circuit 104. TheVCO 100 includes atransistor 102 and an inductiveresonant circuit 104 coupled with a respectivevariable reactance element 106, such as a voltage variable capacitor or varactor, which is responsive to atuning signal 108, VTUNE. Thetuning signal 108 tunes theresonant circuit 104 within its operable predetermined frequency band. Thetuning signal 108 normally tunes theresonant circuit 104 during manufacture to a nominally specified output frequency at a specified control voltage. - In particular, the
base 110 of thetransistor 102 is AC coupled to theresonant circuit 104 through a DC blocking capacitor C2. Theresonant circuit 104 contains an LC circuit which resonates at a desired resonant frequency. The LC circuit forms an equivalent LC network with a capacitor C1 and an inductor L1. Theresonant circuit 104 also includes a voltagevariable reactance element 106 such as a varactor orvariable diode 106. During the operation of the oscillator, theresonant circuit 104 is tuned to selected frequency channels within the operable frequency band. Thevaractor 106 is adjusted by atuning signal 108 coupled to thevaractor 106. As thetuning signal 108 is varied, thevaractor 106 changes its capacitance and theresonant circuit 104 changes its operating frequency. - A feedback capacitor C3 is connected across the base and emitter of the
transistor 102. Another feedback capacitor C4 is connected from the emitter connection to the ground. Resistors R1 and R2 are used as all-frequency chokes for the supply voltage Vp that bias thetransistor 102. The collector of thetransistor 102 is AC-coupled to theRF output 112 through a DC blocking capacitor C5. - FIG. 2 shows an alternative embodiment of the
frequency oscillator circuit 200 in which a fine tuning of the desired frequency is achieved by methods known as a frequency “pushing” and a frequency “pulling.” The frequency pushing involves adjusting or altering the bias voltage of the oscillator at thebase 110 of thetransistor 102. The frequency pulling involves adjusting anoutput load 208 of the VCO circuit through anode 210. - The frequency pushing measures the sensitivity of the
oscillator output frequency 206 to the bias voltage applied at thebase 110 of thetransistor 102 and is expressed in MHz/volt. The output frequency change corresponds to a given change in the bias voltage. - The frequency pulling measures the frequency change due to a non-ideal load. It is measured by noting the frequency change caused by a
load 208 having an arbitrary return loss with all possible phases. Theload 208 can be adjusted with a variable capacitor orvaractor 202. Anadditional transistor 204 is configured to amplify the “frequency pulled” RF signal. - One embodiment of an
input voltage tuner 300 for aVCO 200 is shown in FIG. 3. Thetuner 300 performs self-trimming by setting an input reference voltage and enabling the op-amp 302 to push the VCO frequency. Initially, a phase-locked loop frequency synthesizer is set to a mid-range frequency. The op-amp 302 then appropriately pushes the VCO frequency to obtain the correct frequency with a tuning voltage of approximately 1.5 volts. This voltage is converted to a digital form by an analog-to-digital (A/D)converter 304 and stored in read-only memory (ROM) 306. Finally, a digital-to-analog (D/A)converter 308 converts the stored value into an analog form. This analog voltage provides a constant voltage compensating offset. - An alternative embodiment of the
tuner 300 is shown in adashed line 310. This embodiment performs the digital trimming by frequency pulling. First, the PLL is adjusted to a mid-range frequency. The ROM is then fine tuned to achieve the correct voltage at thevaractor node 210. The voltage at thenode 210 is set by pulling the VCO frequency. The adjusted voltage is set for a constant voltage offset. - FIG. 4 shows a further embodiment of an
input voltage tuner 400 using existing components to determine a correction voltage required for an untrimmed VCO to operate at a nominally specified frequency. The components are either unused spares or shared memory spaces. - As diagramed in FIG. 5, an analog
input operating voltage 402 is converted to a digital voltage by an analog-to-digital converter (ADC) 404 (step 500). The digital voltage is used as a pointer to a look-up table 406 in a memory such as a flash memory. Cellular phones often use flash memories because they are non-volatile and therefore retain information even when their power supply is removed. A processor/controller 410 then directs the look-up table 406 to provide a digital correction voltage corresponding to the converted digital voltage atstep 502. Finally, the correction voltage is converted back to an analog form by a digital-to-analog converter (DAC) 408 to be used as a tuned control voltage 412 (step 304). Thisvoltage 412 is used by the VCO to tune itsresonant circuit 104. - A frequency synthesizer, such as a phase-locked loop, is often used as an up/down converter in communication devices to provide a local oscillator signal. A block diagram of a
frequency synthesizer 600 is shown in FIG. 6. Thesynthesizer 600 includes a reference oscillator such as a temperature-controlled crystal oscillator (TCXO) 602, afrequency divider 608, aphase detector 604, and aloop filter 606. Thesynthesizer 600 also includes theuntrimmed VCO 200 and theinput voltage tuner 400 described above. Theinput voltage tuner 400 is summed into the input node of the VCO to provide an offset voltage such that thephase detector 604 may operate in the center of its tuning range. - Once the
synthesizer 600 in a communication device, such as a cellular phone, is calibrated by thetuner 400, thetuned control voltage 108 is held constant by the phase-locking function of the PLL. Further, a tuner output control voltage 212 may also be applied elsewhere in the VCO circuit to achieve the nominally specified frequency through “pushing” or “pulling” as described above. - A communication device, which includes a frequency oscillator and a frequency synthesizer, can be a transmitter, transceiver, or a receiver. In one embodiment, shown in a block diagram in FIG. 7, a communication receiver comprises a pre-filter700 and an
RF amplifier 702 which provides an output to an associatedradio circuitry 704. The pre-filter 700 and theRF amplifier 702 select a band of RF signals received via anantenna 710. TheRF amplifier 702 is broadly tuned to select several channels or stations from the spectrum of signals impinging on theantenna 710. - An intermediate frequency (IF)
amplifier 712 in theradio circuitry 704 is a highly selective amplifier with a passband perfectly matched to the bandwidth of a single station and a center frequency at some fixed intermediate frequency. An “intermediate” frequency is a frequency below the RF frequencies coming in on theantenna 710 and above the audio frequencies that constitute the modulation. - The
frequency synthesizer 700 includes the tuned VCO. It is tuned to supply a sinusoidal signal, FOUT, at a frequency located above the RF frequencies by an amount equal to the intermediate frequency selected by theIF amplifier 712. Amixer 706 forms the product of the incoming RF signal with the sinusoidal signal from thefrequency synthesizer 600, and produces both sum and difference frequencies. Whenever thesynthesizer 600 is adjusted so that the difference frequencies from a particular station fall within the passband of theIF amplifier 712, theIF amplifier 712 will amplify that particular set of carrier-plus-sidebands while rejecting other nearby spectra. The processor/controller 410 performssynthesizer 600 tuning. - A
peak detector 714 demodulates the down-converted signal, and anaudio amplifier 716 amplifies the demodulated audio-frequency signal. The audio signal is then sent to aspeaker 718. - In another embodiment, the communication device is a transceiver such as in a cellular phone. The synthesizer provides a transmitter local oscillator signal controlled by the VCO. The transmitter and receiver are switchably connected to the antenna under control of the processor/
controller 410. - FIG. 8 shows an exploded view of a
cellular telephone system 800 using the VCO controlledfrequency synthesizer 600 described above. Thecellular telephone system 800 also includes akey pad 802 and various other buttons andindicators 804. Thetelephone system 800 also includes aspeaker 806, amicrophone 808, anantenna 810, andother communication electronics 812 contained within atelephone housing 814. Adisplay unit 816 is used in conjunction with thekeypad 802 to facilitate user inputs. Thecommunication electronics 812 may include, among others, devices such as thefrequency synthesizer 818, theTCXO 820, and theRF amplifier 822. - FIG. 9 shows a
paging device 900 including the VCO controlledfrequency synthesizer 600. Thepaging device 900 also includes communication electronics similar to those in thecellular telephone system 800. - Advantages of replacing the VCO tuning process at the manufacturing stage with an adjustment of a resonant circuit in the VCO during an operation of the oscillator include a lower cost of VCO as well as a low cost implementation of the tuner using existing components and shared memory spaces.
- Other embodiments are within the scope of the following claims. For example, the frequency oscillator described above can be used in other wireless and cellular systems.
Claims (25)
1. A trimmer for adjusting an operating frequency of a frequency oscillator, the trimmer comprising:
a storage element having a set of calibrated data corresponding to a set of input signals; and
a controller configured to utilize the set of calibrated data to provide an appropriate tuning signal for tuning the oscillator to a nominally-specified output frequency.
2. The trimmer of , further comprising:
claim 1
a first converter circuit adapted to convert the set of input signals from an analog to a digital voltage, said first converter circuit enabling the controller to perform its operations digitally; and
a second converter circuit adapted to convert the digital tuning signal to an analog signal.
3. The trimmer of , wherein said set of calibrated data is organized in a look-up table.
claim 1
4. The trimmer of , wherein said storage element includes a flash memory.
claim 1
5. An input voltage tuner for a frequency oscillator, comprising:
a first circuit configured to receive an input tuning signal for the oscillator;
a look-up table which provides a correction value corresponding to said input tuning signal; and
a processor operating to control the look-up table during operation of the oscillator, such that the oscillator operates at a nominally specified output frequency.
6. The tuner of , further comprising:
claim 5
a second circuit configured to convert said correction value generated by the processor into a form operable by the frequency oscillator.
7. The tuner of , wherein said first and second circuits are an ADC and a DAC, respectively.
claim 6
8. A method for adjusting an operating frequency of a frequency oscillator, comprising:
storing a set of calibrated data corresponding to a set of input signals; and
utilizing the set of calibrated data to provide an appropriate tuning signal for tuning the oscillator to a nominally specified output frequency.
9. The method of , further comprising:
claim 8
converting said tuning signal into a form operable by the frequency oscillator.
10. A computer program, residing on a computer readable medium, to adjust an operating frequency of a frequency oscillator, the program comprising executable instructions that enable the computer to:
store a set of calibrated data corresponding to a set of input signals; and
utilize the set of calibrated data to provide an appropriate tuning signal for tuning the oscillator to a nominally specified output frequency.
11. A frequency oscillator comprising:
a tuner operating to provide a tuning signal, the tuner including:
a storage element having a set of calibrated data corresponding to a set of input signals;
a controller configured to utilize the set of calibrated data to provide an appropriate tuning signal for tuning said oscillator to a nominally specified output frequency;
a resonant circuit configured to receive the tuning signal and generate a wave energy signal of a particular frequency corresponding to the tuning signal, such that the particular frequency is substantially close to a nominally specified output frequency of said oscillator.
12. The oscillator of , wherein said tuning signal tunes the resonant circuit by adjusting an equivalent LC network containing a capacitor, an inductor, and a voltage variable reactance element.
claim 11
13. The oscillator of , wherein said voltage variable reactance element is a varactor or variable diode which changes its capacitance according to an applied voltage.
claim 12
14. The oscillator of , further comprising:
claim 11
a first transistor having a base, a collector, and an emitter, said first transistor AC-coupled to the resonant circuit for amplifying the wave energy signal.
15. The oscillator of , further comprising:
claim 14
feedback capacitors placed between the base and the emitter and the emitter and a ground, said feedback capacitors configured to provide negative feedback to the first transistor.
16. The oscillator of , further comprising:
claim 14
a variable resistor network coupled to the base of the first transistor to provide frequency pushing where the particular frequency is fine tuned to the nominally specified output frequency of the oscillator.
17. The oscillator of , further comprising:
claim 14
a variable transistor output load coupled to the collector of the first transistor to provide frequency pulling where the particular frequency is fined tuned to the nominally specified output frequency of the oscillator.
18. The oscillator of , wherein the output load includes a varactor or variable diode which changes its capacitance load according to an applied voltage at the collector of the first transistor.
claim 17
19. The oscillator of , further comprising:
claim 18
a second transistor AC-coupled to the output load and the collector of the first transistor to provide additional stage of amplification.
20. A frequency synthesizer circuit comprising:
a reference oscillator providing a reference frequency signal;
a phase adjustment circuit configured to receive the reference frequency signal and provide an adjusted signal with its phase adjusted to a desired phase;
a frequency oscillator operating to receive said adjusted signal and to provide a tuned signal having a particular frequency, said particular frequency of the tuned signal being substantially close to a nominally specified output frequency of said oscillator,
such that the tuned signal is locked-in to a particular phase and voltage once the nominally specified output frequency is achieved within a specified tolerance.
21. The circuit of , wherein the reference oscillator is a temperature-controlled crystal oscillator.
claim 20
22. The circuit of , wherein the phase adjustment circuit includes a frequency divider, a phase detector, and a loop filter.
claim 20
23. The circuit of , wherein the frequency oscillator comprises:
claim 20
a tuner operating to provide a tuning signal, the tuner including:
a storage element having a set of calibrated data corresponding to a set of input signals;
a controller configured to utilize the set of calibrated data to provide an appropriate tuning signal for tuning said oscillator to a nominally specified output frequency;
a resonant circuit configured to receive the tuning signal and generate a wave energy signal of a particular frequency corresponding to the tuning signal, such that the particular frequency is substantially close to a nominally specified output frequency of said oscillator.
24. A cellular telephone system comprising:
a housing;
electronic components within the housing; and
a frequency synthesizer circuit including:
a reference oscillator providing a reference frequency signal;
a phase adjustment circuit configured to receive the reference frequency signal and provide an adjusted signal with its phase adjusted to a desired phase;
a frequency oscillator operating to receive said adjusted signal and to provide a tuned signal having a particular frequency, said particular frequency of the tuned signal being substantially close to a nominally specified output frequency of said oscillator,
such that the tuned signal is locked in to a particular phase and voltage once the nominally specified output frequency is achieved within a specified tolerance.
25. A paging system comprising:
a housing;
electronic components within the housing; and
a frequency synthesizer circuit including:
a reference oscillator providing a reference frequency signal;
a phase adjustment circuit configured to receive the reference frequency signal and provide an adjusted signal with its phase adjusted to a desired phase;
a frequency oscillator operating to receive said adjusted signal and to provide a tuned signal having a particular frequency, said particular frequency of the tuned signal being substantially close to a nominally specified output frequency of said oscillator, such that the tuned signal is locked in to a particular phase and voltage once the nominally specified output frequency is achieved within a specified tolerance.
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US09/887,912 US6433644B2 (en) | 2000-01-18 | 2001-06-20 | Adjusting untrimmed VCO during operation of the oscillator |
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US09/484,474 US6323739B1 (en) | 2000-01-18 | 2000-01-18 | Adjusting untrimmed VCO during operation of the oscillator |
US09/887,912 US6433644B2 (en) | 2000-01-18 | 2001-06-20 | Adjusting untrimmed VCO during operation of the oscillator |
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US09/484,474 Division US6323739B1 (en) | 2000-01-18 | 2000-01-18 | Adjusting untrimmed VCO during operation of the oscillator |
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US20010035775A1 true US20010035775A1 (en) | 2001-11-01 |
US6433644B2 US6433644B2 (en) | 2002-08-13 |
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US09/887,227 Expired - Fee Related US6509806B2 (en) | 2000-01-18 | 2001-06-20 | Adjusting untrimmed VCO during operation of the oscillator |
US09/887,912 Expired - Fee Related US6433644B2 (en) | 2000-01-18 | 2001-06-20 | Adjusting untrimmed VCO during operation of the oscillator |
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US5748047A (en) * | 1996-08-15 | 1998-05-05 | Northrop Grumman Corporation | Microwave frequency generator and method of generating a desired microwave frequency signal |
IL120119A0 (en) * | 1997-01-31 | 1997-04-15 | Binder Yehuda | Method and system for calibrating a crystal oscillator |
US5912595A (en) * | 1997-12-16 | 1999-06-15 | Ma; John Y. | Digitally temperature compensated voltage-controlled oscillator tunable to different frequency channels |
-
2000
- 2000-01-18 US US09/484,474 patent/US6323739B1/en not_active Expired - Fee Related
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2001
- 2001-06-20 US US09/887,227 patent/US6509806B2/en not_active Expired - Fee Related
- 2001-06-20 US US09/887,912 patent/US6433644B2/en not_active Expired - Fee Related
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10998909B1 (en) | 2019-09-12 | 2021-05-04 | Dialog Semiconductor B.V. | Sensing device comprising a phase locked loop circuit |
Also Published As
Publication number | Publication date |
---|---|
US6509806B2 (en) | 2003-01-21 |
US6433644B2 (en) | 2002-08-13 |
US6323739B1 (en) | 2001-11-27 |
US20010035796A1 (en) | 2001-11-01 |
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