Adjusting untrimmed VCO during operation of the oscillator

• US 6,433,644 B2
• Filed: 06/20/2001
• Issued: 08/13/2002
• Est. Priority Date: 01/18/2000
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Andrews, Joseph
• Primary Examiner(s): Mis, Davis
• Application Number:
  US09/887,912
• Publication Number:
  US 20010035775A1
• Time in Patent Office: 419 Days
• Field of Search: 331/10, 331/16, 331/17, 331/25, 331/34, 331/117.R, 331/177.V, 331/36.C
• US Class Current: 331/10
• 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 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, and;

a variable transistor output load which provides frequency pulling where the particular frequency is fine tuned to the nominally specified output frequency of the oscillator.

2. The circuit of claim 1, wherein the reference oscillator is a temperature-controlled crystal oscillator.

3. The circuit of claim 1, wherein the phase adjustment circuit includes a frequency divider, a phase detector, and a loop filter.

4. The circuit of claim 1, 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.

5. 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, and;

a variable transistor output load which provides frequency pulling where the particular frequency is fine tuned to the nominally specified output frequency of the oscillator.

6. 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, and;

a variable transistor output load which provides frequency pulling where the particular frequency is fine tuned to the nominally specified output frequency of the oscillator.