Adjusting untrimmed VCO during operation of the oscillator

• US 20010035796A1
• Filed: 06/20/2001
• Published: 11/01/2001
• Est. Priority Date: 01/18/2000
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Andrews, Joseph
• Granted Patent: US 6,509,806 B2
• Time in Patent Office: Days
• US Class Current: 331/117R
• CPC Class Codes: H03B 5/1203 the amplifier being a single transistor
• CPC Class Codes: H03B 5/1231 the amplifier comprising one or more bipolar transistors
• CPC Class Codes: H03B 5/1243 the means comprising voltage variable capacitance diodes
• CPC Class Codes: H03C 1/36 by means of semiconductor device having at least three electrodes H03C1/34, H03C1/50, H03C1/52, H03C1/62 take precedence
• CPC Class Codes: H03J 2200/29 Self-calibration of a receiver
• CPC Class Codes: H03L 2207/06 Phase locked loops with a controlled oscillator having at least two frequency control terminals
• CPC Class Codes: H03L 7/099 concerning mainly the controlled oscillator of the loop
• CPC Class Codes: H03L 7/18 using a frequency divider or counter in the loop H03L7/20, H03L7/22 take precedence

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.

Claims

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

claim 1

, further comprising:

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

claim 1

, wherein said set of calibrated data is organized in a look-up table.

4. The trimmer of

claim 1

, wherein said storage element includes a flash memory.

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

claim 5

, further comprising:

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

claim 6

, wherein said first and second circuits are an ADC and a DAC, respectively.

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

claim 8

, further comprising:

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

claim 11

, 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.

13. The oscillator of

claim 12

, wherein said voltage variable reactance element is a varactor or variable diode which changes its capacitance according to an applied voltage.

14. The oscillator of

claim 11

, further comprising:

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

claim 14

, further comprising:

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

claim 14

, further comprising:

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

claim 14

, further comprising:

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

claim 17

, 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.

19. The oscillator of

claim 18

, further comprising:

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

claim 20

, wherein the reference oscillator is a temperature-controlled crystal oscillator.

22. The circuit of

claim 20

, wherein the phase adjustment circuit includes a frequency divider, a phase detector, and a loop filter.

23. The circuit of

claim 20

, wherein the frequency oscillator comprises:

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.