Apparatuses and methods for detecting a loop count in a delay-locked loop
View Patent ↗Apparatuses and methods are disclosed for detecting a loop count in a delay-locked loop that uses a divide clock in a measure initialization process. An example apparatus includes a divider configured to receive a signal and produce a first divided signal and a second divided signal that is complementary to the first divided signal, a first circuit configured to count the first divided signal during a first enabled period and produce a first count value, a second circuit configured to count the second divided signal during a second enabled period and produce a second count value, and an adder configured to produce a third count value responsive to the first and second count values.
1. An apparatus comprising:
a divider configured to receive a signal and produce a first divided signal and a second divided signal that is complementary to the first divided signal, wherein the signal received by the divider is a clock signal;
a first circuit configured to count the first divided signal during a first enabled period and produce a first count value;
a second circuit configured to count the second divided signal during a second enabled period and produce a second count value;
an adder configured to produce a third count value responsive to the first and second count values; and
a delay path configured to receive the clock signal and propagate the clock signal, and change a delay value thereof responsive to the third count value.
2. The apparatus as claimed in claim 1 , wherein the first enabled period is produced responsive to the first divided signal.
3. The apparatus as claimed in claim 2 , wherein the second enabled period is produced responsive to the second divided signal.
4. The apparatus as claimed in claim 3 , wherein the first and second enabled periods are additionally produced responsive to start and stop signals that indicate, respectively, the beginning and end of a timing loop cycle.
5. The apparatus as claimed in claim 4 , wherein the third count value corresponds to a number clock cycles for a reference clock to traverse the timing loop.
6. A method comprising:
receiving a signal and producing a first divided signal and a second divided signal that is complementary to the first divided signal, wherein the signal is a clock signal;
counting the first divided signal during a first enabled period to produce a first count value;
counting the second divided signal during a second enabled period to produce a second count value;
adding the first and second count values to produce a third count value; and
receiving the clock signal and propagating the clock signal, and changing a delay value thereof responsive to the third count value.
7. The method as claimed in claim 6 , further comprising:
producing the first enabled period responsive to the first divided signal.
8. The method as claimed in claim 7 , further comprising:
producing the second enabled period responsive to the second divided signal.
9. The method as claimed in claim 8 , further comprising:
producing the first and second enabled periods additionally responsive to start and stop signals that indicate, respectively, the beginning and end of a timing loop cycle.
10. The method as claimed in claim 9 , wherein the third count value corresponds to a number of clock cycles for a reference clock to traverse the timing loop.