Timing vernier using a delay locked loop
View Patent ↗A method for synchronizing a plurality of programmable timing verniers with a reference pulse signal, each of the vernier being programmable to one of a plurality of timing steps within a delay range and the delay range being determined by a control signal applied to a bias input, the method comprising the steps of selecting a first and second control vernier from the plurality of verniers; programming the first control vernier to a first delay; programming the second control vernier to a second delay; triggering the first and second control verniers together to generate respective first and second delay signals; generating a difference pulse signal having a duty cycle corresponding to a difference between the generated first delay signal and second delay signal; comparing the duty cycle of the pulse signal to a duty cycle of the reference pulse signal to generate a difference signal pulse, the difference signal being coupled to the bias input of the verniers to adjust the delay range such that the duty cycle of the difference signal approaches the duty cycle of the reference pulse signal. In a preferred embodiment there is provided a circuit for implementing the method.
1. A method for synchronizing a programmable timing vernier with a reference signal, the timing vernier being programmable to one of a plurality of timing steps within a delay range, said delay range being controlled by a bias signal applied to a bias input of the timing vernier, said method comprising the steps of:
(a) providing a first and a second control vernier;
(b) programming said first control vernier to a first delay;
(c) programming said second control vernier to a second delay;
(d) triggering said first and second control verniers together to generate respective first and second delay signals;
(e) generating a first difference signal corresponding to a difference between said generated first delay signal and second delay signal; and
(f) comparing the first difference signal to a reference signal to generate a second difference signal, said second difference signal being coupled to the bias input of said vernier to adjust said delay range.
2. A method as defined in claim 1 , said reference signal being a variable frequency clock signal.
3. A method as defined in claim 1 said first delay being a minimum delay of said verniers and said second delay being a maximum delay of said verniers.
4. A method as defined in claim 1 , said second difference signal being a bias voltage.
5. A method as defined in claim 1 , said second difference signal being a bias current.
6. A method as defined in claim 1 , said first difference signal being a pulse and said reference signal also being a pulse.
7. A method as defined in claim 6 , where the second difference signal is generated by comparing the duty cycle of the first difference signal pulse and the duty cycle of the reference signal pulse.
8. A method as defined in claim 7 , where the second difference signal adjusts the delay range such that the duty cycle of the first difference signal pulse approaches the duty cycle of the reference signal pulse.
9. A system for synchronizing a programmable timing vernier with a reference signal, the vernier being programmable to one of a plurality of timing steps within a delay range and the delay range being determined by a bias signal applied to a bias input of the programmable timing vernier, the system comprising:
(a) first and second control verniers programmed to respective first delay and second delays;
(b) a pulse generator for generating a first difference signal corresponding to a difference between a generated first delay signal and second delay signal;
(c) a detector for comparing the first difference signal to the reference pulse signal to generate a second difference signal; and
(d) a feed-back circuit for coupling the second difference signal to the bias input of the vernier to adjust the delay range of said vernier.
10. A system as defined in claim 9 , said second difference signal being a voltage signal and said feedback circuit including a voltage to current converter circuit for converting said voltage signal to a current signal, said current signal being distributed to said programmable timing vernier.
11. A system as defined in claim 9 , said programmable timing vernier including local current to voltage converters for converting said distributed current signal to a voltage signal.
12. A system as defined in claim 11 , said programmable timing vernier being grouped in predetermined numbers and each said group having a common local current to voltage converter.
13. A system as defined in claim 9 , comprising a plurality of programmable timing verniers being synchronized with the reference signal.
14. A method as defined in claim 1 , comprising a plurality of programmable timing verniers being synchronized with the reference signal.