Digital pulse generator using digital slivers and analog vernier increments
First Claim
1. A method for accurately controlling a time relationship between a generated output pulse and a reference time, the method comprising the steps of:
- deriving time quanta from a controllable timebase to produce a coarse time relationship between the generated output pulse and the reference time;
adding digital slivers to modify the coarse time relationship to produce a modified time relationship; and
adjusting the modified time relationship by analog vernier increments to produce an accurately controlled time relationship between the generated output pulse and the reference time.
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Abstract
A digital architecture for a pulse generator includes a triggerable voltage controlled oscillator (VCO) with two alternative sources of frequency control voltage, an internal DAC or a phase frequency comparison with an external timebase. In a top octave of operation, the output of the triggerable VCO is used to produce output pulses whose edge locations are then adjusted by small digital increments or "slivers" and very small analog increments or "verniers". In lower octaves of operation, the contents of a pattern RAM serve to frequency divide the triggerable VCO output frequency by powers of two. The RAM contents are converted to a serial bit stream that imposes the coarse pulse width and period as an integral number of top octave periods, or quanta. The edge locations are then adjusted with slivers and verniers, as in the top octave. Automatic calibration facilities are included. This architecture provides controllable tolerances, permits accurate positioning of a trigger out signal relative to any pulse produced, allows the user to specify the trailing edge timing directly, and permits both pulse width and phase to be specified as a percentage of the overall period and automatically kept proportional when the frequency is varied. It allows synchronized operation of different channels at rates related by powers-of-two, and permits disabling of a channel at an operator determined voltage level. A means for determining, by the use of an external signal, when bursts of pulses synchronized to an external frequency source will begin, is also provided.
30 Citations
10 Claims
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1. A method for accurately controlling a time relationship between a generated output pulse and a reference time, the method comprising the steps of:
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deriving time quanta from a controllable timebase to produce a coarse time relationship between the generated output pulse and the reference time; adding digital slivers to modify the coarse time relationship to produce a modified time relationship; and adjusting the modified time relationship by analog vernier increments to produce an accurately controlled time relationship between the generated output pulse and the reference time. - View Dependent Claims (2, 3, 4, 5)
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6. A method for accurately controlling a time relationship between a generated output pulse and a trigger pulse output, the method comprising the steps of:
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deriving time quanta from a controllable timebase to produce a first coarse time relationship between a generated output pulse and a reference time, and to produce a second coarse time relationship between a trigger pulse output and the reference time; adding digital slivers to modify the first and second coarse time relationships to produce modified time relationships; and adjusting the modified time relationships by analog vernier increments to produce an accurately controlled time relationship between the generated output pulse and the trigger pulse output. - View Dependent Claims (7, 8, 9, 10)
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Specification