Apparatuses and methods for duty cycle error correction of clock signals
Apparatuses and methods for duty cycle error correction of clock signals are disclosed. An example method includes detecting a clock period error between a first clock signal and a third clock signal and adjusting a timing of the first or third clock signals based on the clock period error therebetween. The method further includes detecting a clock period error between a second clock signal and a fourth clock signal and adjusting a timing of the second or fourth clock signals based on the clock period error therebetween. Additionally, the example method includes detecting a duty cycle error between the first, second, third, and fourth clock signals, and adjusting a timing of the first and third or second and fourth clock signals based on the duty cycle error therebetween.
1. An apparatus, comprising:
a duty cycle detector configured to receive a plurality of signals and configured to detect first clock period error between first and second signals and second clock period error between third and fourth signals of the plurality of signals and provide a first control signal indicative of the first clock period error and a second control signal indicative of the second clock period error, the duty cycle detector further configured to detect a duty cycle error relative to the plurality of signals and provide a third control signal indicative of the duty cycle error;
a duty cycle adjustment circuit configured to receive the first, second, and third control signals from the duty cycle detector and configured to provide adjustment signals based on the first, second, and third control signals; and
a signal driver circuit configured to provide the plurality of signals and to receive the adjustment signals, the signal driver circuit further configured to adjust timings of the plurality of signals based on the first, second, and third control signals.
2. The apparatus of claim 1 wherein the duty cycle detector comprises:
a first detector configured to detect the first clock period error and provide the first control signal to the duty cycle adjustment circuit;
a second detector configured to detect the second clock period error and provide the second control signal to the duty cycle adjustment circuit; and
a third detector configured to detect the third clock period error and provide the third control signal to the duty cycle adjustment circuit.
3. The apparatus of claim 2 wherein the plurality of signals comprises a first, second, third, and fourth signals, and wherein:
the first detector is configured to detect the first clock period error between rising edges of the first and third signals,
the second detector is configured to detect the second clock period error between rising edges of the second and fourth signals, and
the third detector is configured to detect the duty cycle error between rising edges of the first and third signals and rising edges of the second and fourth signals.
4. The apparatus of claim 2 wherein the plurality of signals comprises a first, second, third, and fourth signals, and wherein:
the first detector is configured to detect the first clock period error when a time between a first rising edge of the first signal and a rising edge of the third signal is greater than or less than a time between the rising edge of the third signal and a second rising edge of the first signal, and
the second detector is configured to detect the second clock period error when a time between a first rising edge of the second signal and a rising edge of the fourth signal is greater than or less than a time between the rising edge of the fourth signal and a second rising edge of the second signal.
5. The apparatus of claim 2 wherein the plurality of signals comprises a first, second, third, and fourth signals, and wherein the third detector is configured to detect a duty cycle error when a time between a rising edge of the first signal and a rising edge of the second signal is greater than or less than a time between the rising edge of the second signal and a rising edge of the third signal.
6. The apparatus of claim 1 wherein the duty cycle adjustment circuit comprises:
a first code circuit configured to receive the first control signal and provide first code signals based on the first control signal;
a first timing adjustment circuit configured to receive the first code signals and provide adjustment signals, wherein the adjustment signals have current magnitudes based on the first code signals;
a second code circuit configured to receive the second control signal and provide second code signals based on the second control signal; and
a second timing adjustment circuit configured to receive the second code signals and provide adjustment signals, wherein the adjustment signals have current magnitudes based on the second code signals.
7. The apparatus of claim 6 wherein the first code signals comprises a first set of signals and a second set of signals, and wherein first timing adjustment circuit comprises:
a first current circuit configured to provide a first current having a magnitude based on the first set of signals; and
a second current circuit configured to provide a second current having a magnitude based on the second set of signals.
8. A method, comprising:
detecting a clock period error between a first clock signal and a third clock signal;
adjusting a timing of the first or third clock signals based on the clock period error therebetween;
detecting a clock period error between a second clock signal and a fourth clock signal;
adjusting a timing of the second or fourth clock signals based on the clock period error therebetween;
detecting a duty cycle error between the first, second, third, and fourth clock signals; and
adjusting a timing of the first and third or second and fourth clock signals based on the duty cycle error therebetween.
9. The method of claim 8 wherein detecting the clock period error between the first and third clock signals comprises detecting whether rising edges of the third clock signal are halfway between rising edges of the first clock signal.
10. The method of claim 9 wherein detecting a duty cycle error between the first, second, third, and fourth clock signals comprises detecting whether rising edges of the second clock signal are halfway between rising edges of the first clock signal and the third clock signal.
11. The method of claim 8 wherein adjusting the timing of the first or third clock signals based on the clock period error therebetween comprises delaying the first or third clock signals based on the clock period error therebetween.
12. The method of claim 11 wherein delaying the first or third clock signals based on the clock period error therebetween comprises decreasing a rate at which a first input signal or third input signal changes from one level to another, the first clock signal based on the first input signal and the third clock signal based on the third input signal.
13. The method of claim 12 wherein decreasing the rate at which the first input signal or third input signal changes from one level to another comprises providing a current having a magnitude based on the clock period error between the first and third clock signals.
14. The method of claim 8 wherein adjusting the timing of the first and third or second and fourth clock signals based on the duty cycle error therebetween comprises delaying the first and third clock signals or the second and fourth clock signals based on the duty cycle error therebetween.
15. The method of claim 8 wherein the first, second, third, and fourth clock signals are quadrature clock signals.