Patent US5418485A successfully refreshed from Google Patents.
← Back to Patent Explorer
US5418485A Expired / Lapsed US ⏱️ 0.0 years remaining

Clock signal conditioning circuit

Assignee: NXP USA Inc
•
Filing: 1993-12-20
•
Granted: 1995-05-23
•
Expires: 2013-12-20
📄 Original PDF 🌐 Google Patents 🔄 Sync Now

Abstract

Abstract A clock signal conditioning circuit (100) for use in a smart card (102) has an input node (112) for receiving an applied clock signal, an output node (126) for producing a conditioned clock signal, a rising/falling edge detector (118) for detecting edges in the received clock signal, a bistable device (122) for forming at the output node a clock signal in response to the edge detector, and a timer (120, 124) for inhibiting switching of the bistable device for a predetermined time (T) following detection by the edge detector of an edge. Such a clock signal conditioning circuit provides a conditioned clock signal which is substantially independent of variations in the duty cycle of the applied clock signal and is substantially immune to glitches in the applied clock signal.

Inventors

  • 👤 Alain Duret
  • 👤 Eric Boulian
  • 👤 Anil Gercekci

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-01 10:45
CPC Classifications
G; G06; G06K; G06K19/00; G06K19/06; G06K19/067; G06K19/07; G06K7/00; G06K7/0008; H; H03; H03K; H03K5/00; H03K5/125; H03K5/1252; H03K5/156; H03K5/1565

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 174 words
A clock signal conditioning circuit, comprising: an input node for receiving an applied clock signal; an output node for producing thereat a conditioned clock signal; edge detector means for detecting edges in the applied clock signal, wherein the edge detector means comprises a first edge detector for detecting an edge of a first polarity, and a second edge detector for detecting an edge of a second polarity opposite to the first polarity; bistable means for forming at the output node a clock signal in response to the edge detector means; and timer means for inhibiting switching of the bistable means for a predetermined time following detection by the edge detector means of an edge, wherein the timer means comprises a first monostable pulse generator arranged to be triggered in response to the first edge detector and having an output coupled to disable the second edge detector, and a second monostable pulse generator arranged to be triggered in response to the second edge detector and having an output coupled to disable the first edge detector.
Claim 2
Dependent Claim 174 words
A clock signal conditioning circuit, comprising: an input node for receiving an applied clock signal; an output node for producing thereat a conditioned clock signal; edge detector means for detecting edges in the applied clock signal, wherein the edge detector means comprises a first edge detector for detecting an edge of a first polarity, and a second edge detector for detecting an edge of a second polarity opposite to the first polarity; bistable means for forming at the output node a clock signal in response to the edge detector means; and timer means for inhibiting switching of the bistable means for a predetermined time following detection by the edge detector means of an edge, wherein the timer means comprises a first monostable pulse generator arranged to be triggered in response to the first edge detector and having an output coupled to disable the second edge detector, and a second monostable pulse generator arranged to be triggered in response to the second edge detector and having an output coupled to disable the first edge detector.
Claim 3
Dependent Claim 28 words
A clock signal conditioning circuit according to claim 1 further comprising pulse stretching means coupled to the edge detector means for stretching pulses of the conditioned clock signal.
Claim 4
Dependent Claim 230 words
A clock signal conditioning circuit, comprising: an input node for receiving an applied clock signal; an output node for producing thereat a conditioned clock signal; edge detector means for detecting edges in the applied clock signal, wherein the edge detector means comprises a first edge detector for detecting an edge of a first polarity, and a second edge detector for detecting an edge of a second polarity opposite to the first polarity; bistable means for forming at the output node a clock signal in response to the edge detector means; and timer means for inhibiting switching of the bistable means for a predetermined time following detection by the edge detector means of an edge, wherein the timer means comprises: a first monostable pulse generator arranged to be triggered in response to the first edge detector; a second monostable pulse generator arranged to be triggered in response to the second edge detector; first logic means having inputs coupled to the output of the first edge detector and to the outputs of the first and second monostable pulse generators and having an output coupled to a first input of the bistable means; and second logic means having inputs coupled to the output of the second edge detector and to the outputs of the first and second monostable pulse generators and having an output coupled to a second input of the bistable means.
Claim 5
Dependent Claim 230 words
A clock signal conditioning circuit, comprising: an input node for receiving an applied clock signal; an output node for producing thereat a conditioned clock signal; edge detector means for detecting edges in the applied clock signal, wherein the edge detector means comprises a first edge detector for detecting an edge of a first polarity, and a second edge detector for detecting an edge of a second polarity opposite to the first polarity; bistable means for forming at the output node a clock signal in response to the edge detector means; and timer means for inhibiting switching of the bistable means for a predetermined time following detection by the edge detector means of an edge, wherein the timer means comprises: a first monostable pulse generator arranged to be triggered in response to the first edge detector; a second monostable pulse generator arranged to be triggered in response to the second edge detector; first logic means having inputs coupled to the output of the first edge detector and to the outputs of the first and second monostable pulse generators and having an output coupled to a first input of the bistable means; and second logic means having inputs coupled to the output of the second edge detector and to the outputs of the first and second monostable pulse generators and having an output coupled to a second input of the bistable means.
Claim 6
Dependent Claim 58 words
A clock signal conditioning circuit according to claim 3 arranged to produce a signal having a frequency which is an integer multiple of the applied clock signal frequency and comprising a frequency divider means coupled to receive the signal and to produce therefrom another signal having a desired frequency dependent on the frequency of the applied clock signal.
Claim 7
Dependent Claim 17 words
A clock signal conditioning circuit according to claim 1 wherein the bistable means comprises a data latch.
Claim 8
Dependent Claim 16 words
A clock signal conditioning circuit according to claim 1 wherein the bistable means comprises a flip-flop.
Claim 9
Dependent Claim 58 words
A clock signal conditioning circuit according to claim 1 arranged to produce a signal having a frequency which is an integer multiple of the applied clock signal frequency and comprising a frequency divider means coupled to receive the signal and to produce therefrom another signal having a desired frequency dependent on the frequency of the applied clock signal.

References Cited (Backward Citations)

US3693028A Cited
GB1408116A Cited
US3942042A Cited
US3921081A Cited
US3965431A Cited
US4588905A Cited
US4606053A Cited
US4635280A Cited
GB2187005A Cited
US5003196A Cited
US4937468A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1998-05-22 1998-11-21 1999-05-23 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 2002-05-22 2002-11-21 2003-05-23 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2006-05-22 2006-11-21 2007-05-23 $7700.00 Window Closed / Lapsed

Assigned Categories & Tags

No categories assigned to this patent yet.

Assign Category Tag