US5854575A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual-loop phase-locked loop
Assignee: Avago Technologies International Sales Pte Ltd
•
Filing: 1997-11-13
•
Granted: 1998-12-29
•
Expires: 2017-11-13
Abstract
Abstract An integrated circuit phase-locked loop includes a phase/frequency detector, a charge pump, and a voltage-controlled oscillator (VCO) which are coupled together in series. The VCO has first and second VCO control inputs, and has a VCO output which is coupled to the phase/frequency detector. An off-chip loop filter input is coupled between the charge pump and the first VCO control input for coupling to an off-chip loop filter. An on-chip loop filter is coupled between the first VCO control input and the second VCO control input. The VCO has a lower voltage-to-frequency gain from the first VCO control input to the VCO output than from the second VCO control input to the VCO output.
Inventors
- 👤 Alan S. Fiedler
- 👤 Daniel J. Baxter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 09:35
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/085; H03L7/093; H03L7/10; H03L7/107; H03L7/1075
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
110 words
An integrated circuit comprising: a phase/frequency detector, a charge pump, and a voltage-controlled oscillator (VCO) which are coupled together in series to form a phase-locked loop, wherein the VCO has first and second VCO control inputs and has a VCO output coupled to the phase/frequency detector, and wherein the VCO has a lower voltage-to-frequency gain from the first VCO control input to the VCO output than from the second VCO control input to the VCO output; an off-chip loop filter input coupled between the charge pump and the first VCO control input; and an on-chip loop filter coupled between the first VCO control input and the second VCO control input.
Claim 2
Dependent Claim
110 words
An integrated circuit comprising: a phase/frequency detector, a charge pump, and a voltage-controlled oscillator (VCO) which are coupled together in series to form a phase-locked loop, wherein the VCO has first and second VCO control inputs and has a VCO output coupled to the phase/frequency detector, and wherein the VCO has a lower voltage-to-frequency gain from the first VCO control input to the VCO output than from the second VCO control input to the VCO output; an off-chip loop filter input coupled between the charge pump and the first VCO control input; and an on-chip loop filter coupled between the first VCO control input and the second VCO control input.
Claim 3
Dependent Claim
16 words
The integrated circuit of claim 1 wherein the on-chip loop filter comprises a first-order RC filter.
Claim 4
Dependent Claim
52 words
The integrated circuit of claim 2 wherein the VCO further comprises a reference voltage input and wherein the first-order RC filter comprises a resistor coupled between the first VCO control input and the second VCO control input and a capacitor coupled between the second VCO control input and the reference voltage input.
Claim 5
Dependent Claim
53 words
The integrated circuit of claim 2 wherein the VCO further comprises a reference voltage input and wherein the first-order RC filter comprises a transimpedance amplifier coupled between the first VCO control input and the second VCO control input and a capacitor coupled between the second VCO control input and the reference voltage input.
Claim 6
Dependent Claim
109 words
The integrated circuit of claim 1 wherein: the charge pump comprises first and second differential charge pump outputs; the first VCO control input comprises first and second differential VCO control inputs which are coupled to the first and second differential charge pump outputs, respectively; the second VCO control input comprises third and fourth differential VCO control inputs which are coupled to the first and second differential charge pump outputs, respectively, through the on-chip loop filter; and the off-chip loop filter input comprises a first integrated circuit pin coupled to the first differential charge pump output and a second integrated circuit pin coupled to the second differential charge pump output.
Claim 7
Dependent Claim
29 words
The integrated circuit of claim 1 and further comprising a divide by N frequency divider coupled between the VCO and the phase/frequency detector, where N is a positive integer.
Claim 8
Dependent Claim
121 words
A phase-locked loop comprising: an integrated circuit comprising: a phase/frequency detector, a charge pump, and a voltage-controlled oscillator (VCO) which are coupled together in series, wherein the VCO has first and second VCO control inputs coupled to the charge pump and has a VCO output, and wherein the VCO has a lower voltage-to-frequency gain from the first VCO control input to the VCO output than from the second VCO control input to the VCO output; and an on-chip loop filter coupled between the first VCO control input and the second VCO control input; and an off-chip loop filter coupled between the charge pump and the first VCO control input, wherein the off-chip loop filter is located off of the integrated circuit.
Claim 9
Dependent Claim
121 words
A phase-locked loop comprising: an integrated circuit comprising: a phase/frequency detector, a charge pump, and a voltage-controlled oscillator (VCO) which are coupled together in series, wherein the VCO has first and second VCO control inputs coupled to the charge pump and has a VCO output, and wherein the VCO has a lower voltage-to-frequency gain from the first VCO control input to the VCO output than from the second VCO control input to the VCO output; and an on-chip loop filter coupled between the first VCO control input and the second VCO control input; and an off-chip loop filter coupled between the charge pump and the first VCO control input, wherein the off-chip loop filter is located off of the integrated circuit.
Claim 10
Dependent Claim
26 words
The phase-locked loop of claim 7 wherein the off-chip loop filter comprises a second-order loop filter and the on-chip loop filter comprises a first-order loop filter.
Claim 11
Dependent Claim
135 words
The phase-locked loop of claim 7 wherein: the VCO further comprises a reference voltage input; the integrated circuit further comprises a first external loop filter pin coupled to the charge pump and the first VCO control input and a second external loop filter pin coupled to the reference voltage input; the off-chip loop filter comprises a first resistor and a first capacitor coupled in series between the first and second external loop filter pins and comprises a second capacitor coupled between the first and second external loop filter pins, in parallel with the first resistor and the first capacitor; and the on-chip loop filter comprises a third resistor coupled between the charge pump and the second VCO control input and a third capacitor coupled between the second VCO control input and the reference voltage input.
Claim 12
Dependent Claim
29 words
The phase-locked loop of claim 7 and further comprising a divide by N frequency divider coupled between the VCO and the phase/frequency detector, where N is a positive integer.
Claim 13
Independent Claim
148 words
A method of generating a feedback signal in a phase-locked loop (PLL) on an integrated circuit, the method comprising: comparing a phase and frequency of a reference signal to a phase and frequency of the feedback signal and generating a charge pump control signal as a function of the comparison; pumping charge onto and off of a circuit node as a function of the charge pump control signal; generating first and second frequency control voltages based on the charge pumped onto and off of the circuit node; filtering the first frequency control voltage with an off-chip loop filter; filtering the second frequency control voltage with an on-chip loop filter; controlling the phase and frequency of the feedback signal as a function of the filtered first frequency control voltage; and controlling a center frequency of the feedback signal and as a function of the filtered second frequency control voltage.
Claim 14
Independent Claim
148 words
A method of generating a feedback signal in a phase-locked loop (PLL) on an integrated circuit, the method comprising: comparing a phase and frequency of a reference signal to a phase and frequency of the feedback signal and generating a charge pump control signal as a function of the comparison; pumping charge onto and off of a circuit node as a function of the charge pump control signal; generating first and second frequency control voltages based on the charge pumped onto and off of the circuit node; filtering the first frequency control voltage with an off-chip loop filter; filtering the second frequency control voltage with an on-chip loop filter; controlling the phase and frequency of the feedback signal as a function of the filtered first frequency control voltage; and controlling a center frequency of the feedback signal and as a function of the filtered second frequency control voltage.
Claim 15
Dependent Claim
59 words
The method of claim 11 wherein controlling the phase and frequency of the feedback signal comprises applying a first voltage-to-frequency gain from the first frequency control voltage to the feedback signal and applying a second voltage-to-frequency gain from the second frequency control voltage to the feedback signal, wherein the first voltage-to-frequency gain is less than the second voltage-to-frequency gain.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-12-28 | 2002-06-29 | 2002-12-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-12-28 | 2006-06-29 | 2006-12-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-12-28 | 2010-06-29 | 2010-12-29 | $7700.00 | Window Closed / Lapsed |