EP0647032A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Charge pump circuit with symmetrical current output for phase-controlled loop system
Assignee: International Business Machines Corp
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Filing: 1994-09-08
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Granted: —
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Expires: 2014-09-08
Abstract
Abstract A phase-controlled loop system having a charge pump circuit including a current mismatch measurement circuit and a current compensation circuit for equalizing the amplitude of positive current pulses and the amplitude of negative current pulses output when the phase-controlled loop system is in phase-locked condition. The current mismatch measurement circuit includes duplicate complementary current sources with characteristics and biasing substantially identical to that of the primary current sources providing the positive current and the negative current to the output node of the charge pump circuit. At the common connected node between the duplicate complementary current sources an error current is produced having an amplitude equal to the difference between the amplitude of the positive current pulses and the amplitude of the negative current pulses to the output node. Current mirrors then reflect this error current back to either the positive current source or the negative current source for combining with the positive current or negative current, respectively, such that the currents' amplitudes at the output node substantially cancel. Various current mismatch measurement circuit and current compensation circuit embodiments are described, including a time multiplexed sensing and compensation approach.
Inventors
- 👤 John Edwin Gersbach
- 👤 Ilya Iosefovich Novof
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 06:26
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/085; H03L7/089; H03L7/0891; H03L7/0895; H03L7/0896
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
159 words
A current source circuit for use in a phase-controlled loop system having a filter (16), said current source circuit comprising: an output node (19) coupled to the filter (16) so as to provide a control voltage thereto; a charge pump (14) having means for sourcing a positive current to the output node and means for sourcing a negative current from the output node, said positive current and said negative current each having an amplitude dependent upon the control voltage at the output node; and feedback means (32) for sensing an amplitude difference between the amplitude of the positive current and the amplitude of the negative current when the phase-controlled system is in a phase-locked condition and for compensating at the output node for said amplitude difference so that the amplitude difference between the positive current and the negative current supplied by the charge pump is cancelled at the output node when the phase-controlled loop system is in phase-locked condition.
Claim 2
Dependent Claim
80 words
The current source circuit of claim 1, wherein the charge the pump (14) comprises a primary pair (H4, H12) of complementary current sources connected to the output node, each current source of said primary pair of complementary current sources supplying a different one of a positive current and a negative current to said output node, said positive current and said negative current each having an amplitude dependent upon the control voltage at the output node when in a phase-locked condition.
Claim 3
Dependent Claim
59 words
The current source circuit of claim 1 or 2, wherein said feedback means (32) includes means for producing an error current having an amplitude equal to said difference and means for providing the error current to the output node such that the amplitude difference is canceled at the output node when the phase-controlled loop system is in phase-locked condition.
Claim 4
Dependent Claim
35 words
The current source circuit according to any one of the above claims, wherein said feedback means (32) includes, means for providing the error current to the output node such that the amplitude difference is canceled.
Claim 5
Dependent Claim
84 words
The current source circuit of claim 4, wherein said feedback means (32) includes a secondary pair of complementary current sources connected to produce identical positive and negative currents to the positive and negative currents, respectively, produced by said primary pair of complementary current sources when the phase-controlled loop system is in said phase-locked condition, said feedback means including a current mismatch measurement circuit for determining the current mismatch between the positive current and the negative current of the secondary pair of complementary current sources.
Claim 6
Dependent Claim
69 words
The current source circuit of claim 5, wherein the current sources of said secondary pair of complementary current sources are connected in series with a common node therebetween, and wherein said sensing means further includes a voltage follower circuit connected between the output node and the common node of said secondary pair of complementary current sources for translating the control voltage at the output node to the common node.
Claim 7
Dependent Claim
74 words
The current source circuit of claim 6, wherein said voltage follower circuit comprises an operational amplifier having a first input connected to the output node and a second input connected to the common node of said secondary pair of complementary current sources, an output of said operational amplifier being connected to a source follower circuit, said source follower circuit also being connected to said common node of said secondary pair of complementary current sources.
Claim 8
Dependent Claim
86 words
The current source circuit of claim 4, wherein said means for providing the error current to the output node includes a first current mirror feedback circuit and a second current mirror feedback circuit, said first current mirror feedback circuit being connected to reflect said error signal to the output node when said error signal comprises a positive feedback current and said second current mirror feedback circuit being connected to reflect said error signal to the output node when said error signal comprises a negative feedback current.
Claim 9
Dependent Claim
129 words
The current source circuit according to any one of the above claims, further comprising a first switch means and a second switch means, said first switch means being connected to control output to the output node of the positive current produced by a current source of the primary pair of complementary current sources and said second switch means being connected to control output to the output node of the negative current produced by the other current source of said primary pair of complementary current sources, said feedback means being coupled to said primary pair of complementary current sources such that said first switch means controls transfer of positive feedback current to the output node and said second switch means controls transfer of negative feedback current to the output node.
Claim 10
Dependent Claim
73 words
The current source circuit according to any one of the above claims, wherein said feedback means (32) includes means for time multiplexing the positive current and the negative current produced by the primary pair of complementary current sources between the output node and the means for sensing the amplitude difference between the amplitude of the positive current and the amplitude of the negative current when the phase-controlled loop system is in phase-locked condition.
Claim 11
Dependent Claim
52 words
The current source circuit of claim 10, wherein said means for compensating for the amplitude difference includes means for producing a correction value, and wherein said time multiplexing means includes a capacitor to hold the correction value when the positive current and the negative current are time multiplexed to the output node.
Claim 12
Dependent Claim
43 words
The current source circuit according to any one of the above claims, wherein said phase-controlled loop system comprises a phase-locked loop (PLL) system wherein the control voltage provided by the output node drives a voltage controlled oscillator which provides an output clock signal.
Claim 13
Dependent Claim
133 words
A phase-locked loop (PLL) system for providing an output signal in phase with a received reference signal, said PLL system comprising: a current source circuit according to any one of the above claims; a phase comparator (12) having a first input (Fin) and a second input (13), said first input being coupled to receive the reference signal and said second input being coupled to receive as feedback an output signal (Font), said phase comparator (12) including means for comparing the phases of the reference signal and the output signal and for selectively providing one of a charge increase command and a charge decrease command; and a voltage controlled oscillator (18) coupled to said filter (16) for providing the output signal (Font) in response to a control voltage applied to the filter node (19).
References Cited (Backward Citations)
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