# US 5,703,838 A · Vernier delay line interpolator and coarse counter realignment > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,703,838 A - Document ID: US5703838A - Status: Granted - Kind: A - Application number: 08/602,904 - Filed: 1996-02-16 - Granted: 1997-12-30 - Earliest claimed: 1996-02-16 - Assignees: LeCroy Corporation - Inventors: Mark S. Gorbics; Keith M. Roberts; Richard L. Sumner - Web page: https://patentgrep.com/patent/US5703838A ## CPC - H03M 1/0697: {in time, e.g. using additional comparison cycles} - G04F 10/06: by measuring phase {(G04F10/005 takes precedence)} - H03K 5/159: Applications of delay lines not covered by the preceding subgroups - H03M 1/50: with intermediate conversion to time interval (H03M1/64 takes precedence) - H03M 1/502: {using tapped delay lines} - H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C) - G04F: TIME-INTERVAL MEASURING (measuring pulse characteristics G01R, e.g. G01R29/02; in radar or like systems G01S) - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) ## Abstract A Vernier delay line interpolator provides a precision level smaller than a clock period by delaying a periodic pulse signal in a delay line which has equally time-spaced taps and a total delay that is a harmonic H greater than 1 of the pulse period. The taps of the delay line are latched and decoded to derive the fraction of the pulse period that has passed. When the interpolator is combined with a coarse counter, misalignment between their outputs is prevented by having the coarse counter count both edges of the periodic pulse signal so as to provide redundant bits between the counter and the interpolator. If the redundant bits are not equal, the counter output is corrected before it is combined with the output of the interpolator. ## Claims ### Claim 1 A vernier delay line interpolator for measuring an interval of time smaller than a pulse period, comprising: a tapped delay line for receiving a clock signal having a predetermined pulse period and including a plurality of taps at equal time-intervals along the delay line, the total delay of said delay line being a harmonic H greater than 1 of the pulse period; latch means for latching the taps of said tapped delay line; and decoding means for decoding the latched taps to derive a value representative of a fraction of said pulse period. ### Claim 2 (depends on 1) The vernier delay line interpolator of claim 1, wherein the harmonic H and the number of taps of the delay line are relatively prime. ### Claim 3 (depends on 2) The vernier delay line interpolator of claim 2, wherein the smallest interval of time measured is the pulse period divided by the number of taps of the delay line. ### Claim 4 (depends on 2) The vernier delay line interpolator of claim 2, wherein the tapped delay line includes N delay elements, each delay element having a delay length D and having an output representing a respective one of said taps of said delay line. ### Claim 5 (depends on 4) The vernier delay line interpolator of claim 4, wherein T is the pulse period and t.sub.LBS represents the smallest interval of time measured by said vernier delay line interpolator, and having the relationship: ##EQU3## ### Claim 6 (depends on 2) The vernier delay line interpolator of claim 2, wherein said decoding means includes means for de-permuting the latched taps to derive a de-permuted pattern consisting of N bits corresponding to the number of taps of the delay line, and means for identifying a leading edge transition of said de-permuted pattern as the number of 1/N fractions of the pulse period that have passed since arrival of a last leading edge of said clock signal to said tapped delay line. ### Claim 7 (depends on 6) The vernier delay line interpolator of claim 6, wherein said means for de-permuting the latched taps derives the de-permuted pattern using the permutation P, where ##EQU4## ### Claim 8 (depends on 6) The vernier delay line interpolator of claim 6, further comprising means for removing bubble errors in said de-permuted pattern to produce a corrected de-permuted pattern, and said means for identifying identifies the leading edge transition of said corrected de-permuted pattern. ### Claim 9 A method for measuring an interval of time smaller than a pulse period, comprising the steps of: delaying a periodic pulse signal having a predetermined pulse period in a delay line having N equally time-spaced taps, the total delay of said delay line being a harmonic H greater than 1 of the pulse period; latching each of the taps of said delay line; and decoding the latched taps to derive a value representative of a fraction of said pulse period that has passed at said instant in time. ### Claim 10 (depends on 9) The method of claim 9, wherein the harmonic H and the number of taps of the delay line are relatively prime. ### Claim 11 (depends on 10) The method of claim 10, wherein the smallest interval of time measured is the pulse period divided by the number of taps of the delay line. ### Claim 12 (depends on 10) The method of claim 10, wherein the pulse signal is delayed by an amount D between adjacent taps of said delay line, T is the pulse period, and t.sub.LBS represents the smallest interval of time measured in said method, and having the relationship: ##EQU5## ### Claim 13 (depends on 10) The method of claim 10, wherein said step of decoding is carried out by de-permuting the latched taps to derive a de-permuted pattern consisting of N bits corresponding to the number of taps of the delay line, and identifying a leading edge transition of said de-permuted pattern as the number of 1/N fractions of the pulse period that have passed since arrival of a last leading edge of said pulse signal to said delay line. ### Claim 14 (depends on 13) The method of claim 13, wherein the latched taps are de-permuted using the permutation P, where ##EQU6## ### Claim 15 (depends on 13) The method of claim 13, further comprising means for removing bubble errors in said de-permuted pattern to produce a corrected de-permuted pattern, and said step of decoding identifies the leading edge transition of said corrected de-permuted pattern.