Glitch free delay line multiplexing technique
First Claim
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1. A glitch free delay line system comprising:
- a clock signal;
a variable delay line comprising a plurality of sequentially coupled delay units, wherein the delay line comprises M output nodes and each of the M output nodes reproduces the clock signal with a varying amount of delay;
a select mechanism for choosing a predetermined amount of delay n, and for generating a selection signal in response thereto;
an M-to-N multiplexor having;
M inputs for receiving each of the delayed clock signals from the M output nodes,a select input for receiving the selection signal from the select mechanism, andN output lines, wherein 3<
N<
M, and wherein three of the N output lines provide clock signals having delays of n, n-1, and n+1; and
an N-to-1 multiplexor having;
N inputs coupled to the N output lines of the M-to-N multiplexor,a select input for receiving the selection signal from the select mechanism, andan output line, wherein the output line outputs the clock signal with n delay.
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Abstract
A glitch free delay line multiplexing technique is described that includes an intermediate multiplexing system and an output multiplexer. The intermediate multiplexing system receives signals from a plurality of delay units and outputs a subset of delay signals that includes the signal presently selected, the signal presently selected with an additional delay, and the signal presently selected with one less delay. The intermediate multiplexing system receives a control word from a select mechanism in a non-time critical manner. The output multiplexer receives the least significant bits of the control word and outputs the selected signal.
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Citations
16 Claims
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1. A glitch free delay line system comprising:
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a clock signal; a variable delay line comprising a plurality of sequentially coupled delay units, wherein the delay line comprises M output nodes and each of the M output nodes reproduces the clock signal with a varying amount of delay; a select mechanism for choosing a predetermined amount of delay n, and for generating a selection signal in response thereto; an M-to-N multiplexor having; M inputs for receiving each of the delayed clock signals from the M output nodes, a select input for receiving the selection signal from the select mechanism, and N output lines, wherein 3<
N<
M, and wherein three of the N output lines provide clock signals having delays of n, n-1, and n+1; andan N-to-1 multiplexor having; N inputs coupled to the N output lines of the M-to-N multiplexor, a select input for receiving the selection signal from the select mechanism, and an output line, wherein the output line outputs the clock signal with n delay. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A glitchless delay line circuit, comprising:
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delay means for generating a plurality of delayed clock signals; selection means for selecting one of the plurality of delayed clock signals, the selected clock signal having a delay of n; filter means for generating a subset of delayed clock signals, wherein the subset includes clock signals having delays of n, n+1 and n-1; and output means for receiving the subset of delayed clock signals and for generating the clock signal having n delay. - View Dependent Claims (8, 9)
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10. A delay lock loop comprising:
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a phase detection system; and a variable delay line, comprising; a plurality of delay units for generating a plurality of delayed clock signals, wherein each has a varying amount of delay; a selection mechanism for selecting the clock signal having n delay; a filter mechanism for generating a subset of delayed clock signals, wherein the subset includes clock signals having delays of n, n+1 and n-1; and an output mechanism for receiving the subset of delayed clock signals and for generating the clock signal having n delay. - View Dependent Claims (11, 12)
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13. A delay line circuit, comprising:
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a delay system for generating a plurality of delayed clock signals; a selection system for selecting one of the plurality of delayed clock signals, the selected clock signal having a delay of n; a filter system for generating a subset of delayed clock signals, wherein the subset includes clock signals having delays of n, n+1 and n-1; and an output system for receiving the subset of delayed clock signals and for generating the clock signal having n delay. - View Dependent Claims (14, 15)
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16. A method for generating a glitch free delayed clock signal, comprising the steps of:
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generating a plurality of delayed clock signals; selecting one of the plurality of delayed clock signals, the selected clock signal having a delay of n; generating a subset of delayed clock signals, wherein the subset includes clock signals having delays of n, n+1 and n-1; and receiving the subset of delayed clock signals and generating the clock signal having n delay.
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Specification