1. A method of improving a duty cycle of a periodic signal, the method comprising:
receiving a periodic signal;
delaying the periodic signal a fixed duration to generate a first signal;
delaying the periodic signal a variable duration to generate a second signal, the variable duration controlled by a count;
using the first signal and the second signal to construct an output signal;
integrating the output signal;
with the integrated output signal, using successive approximation to generate a first plurality of bits of the count; and
with the integrated output signal, linearly generating a second plurality of bits of the count.
2. The method of claim 1 wherein the periodic signal is a clock signal.
3. The method of claim 1 wherein the variable duration may be set to be shorter than, equal to, or longer than the fixed delay.
4. The method of claim 1 wherein first edges of the first signal and second edges of the second signal are used to construct the output signal.
5. The method of claim 1 wherein the first plurality of bits of the count comprise the most significant bits of the count.
6. The method of claim 1 wherein the second plurality of bits of the count comprise the least significant bits of the count.
7. A circuit to improve a duty cycle of a periodic signal, the circuit comprising:
a fixed delay element to provide a fixed delay;
a variable delay element to provide a variable delay, the variable delay controlled by a count;
a latch circuit coupled to an output of the fixed delay element and an output of the variable delay element to provide an output signal having an improved duty cycle;
an integrator coupled to an output of the latch circuit to integrate an input signal;
a successive approximation logic circuit coupled to an output of the integrator and to provide a first part of the count; and
a linear logic circuit coupled to an output of the integrator and to provide a second part of the count.
8. The circuit of claim 7 wherein the fixed delay element and the variable delay element are coupled to receive the periodic signal.
9. The circuit of claim 8 wherein the periodic signal is a clock signal.
10. The circuit of claim 7 wherein the first part of the count comprises the most significant bits of the count.
11. The circuit of claim 10 wherein the second part of the count comprises the least significant bits of the count.
12. The circuit of claim 7 wherein the fixed delay element and the variable delay element comprise current-starved inverters.
13. The circuit of claim 7 wherein the latch circuit uses first edges of the output of the fixed delay element and second edges of the output of the variable delay element to generate the output signal.
14. The circuit of claim 7 wherein the circuit is located on a dynamic random access memory.
15. A method of generating an output clock signal having an improved duty cycle, the method comprising:
receiving an input clock signal;
delaying the input clock signal a variable duration;
using the delayed input clock signal to generate the output clock signal;
determining whether the duty cycle of the output clock signal is less than or greater than 50 percent;
using the determination in a successive approximation to generate bits for a count, wherein the count sets the variable duration; and
using the determination in a linear approximation to generate bits for the count.
16. The method of claim 15 wherein the input clock signal is received from a delay-locked loop.
17. The method of claim 15 wherein the output clock signal is provided to a delay-locked loop.
18. The method of claim 15 wherein the successive approximation generates the most significant bits of the count.
19. The method of claim 15 wherein the linear approximation generates the least significant bits of the count.
20. The method of claim 15 wherein first edges of the delayed input clock signal are used to generate the output clock signal.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An apparatus, for use in a receiver configured to receive an electronic video signal, wherein the video signal includes a luminance component that is encoded with amplitude modulation and a chrominance component that is encoded with frequency modulation on a carrier frequency, the apparatus comprising:
a first filter device configured to receive the video signal and output a substantial portion of the luminance component as a received luminance component;
a second filter device configured to receive the video signal and output a substantial portion of the chrominance component as a received chrominance component;
a leakage detector device configured to receive the carrier frequency of the chrominance component and output a leakage detection signal; and
a variable signal adder configured to receive the leakage detection signal and to make a determination as to whether to add a portion of the received chrominance component to the received luminance component; and
wherein the first filter device is further configured to receive the leakage detection signal, compare the leakage detection signal to a first threshold and adjust the filtering bandwidth of the first filter device based on the comparison.
2. The apparatus of claim 1 wherein the variable signal adder determining whether to add a portion of the received chrominance component to the received luminance component includes determining a difference between the leakage detection signal and a second threshold.
3. The apparatus of claim 1 further comprising a variable signal reducer configured to receive the leakage detection signal and to make a determination as to whether to reduce a portion of the received chrominance component.
4. The apparatus of claim 1 wherein the first filter device, the second filter device, the leakage detector device, and the variable signal adder are disposed on a semiconductor chip.
5. An apparatus, for use in a receiver configured to receive an electronic video signal, wherein the video signal includes a luminance component that is encoded with amplitude modulation and a chrominance component that is encoded with frequency modulation on a carrier frequency, the apparatus comprising:
a first filter device configured to receive the video signal and output a substantial portion of the luminance component as a received luminance component;
a second filter device configured to receive the video signal and output a substantial portion of the chrominance component as a received chrominance component;
a leakage detector device configured to receive the carrier frequency of the chrominance component and output a leakage detection signal;
a demodulation device configured to demodulate the received chrominance component and output a chrominance component signal; and
a variable signal reducer configured to receive the leakage detection signal and to make a determination as to whether to reduce a portion of the chrominance component signal; and
wherein the first filter device is further configured to receive the leakage detection signal, compare the leakage detection signal to a first threshold and adjust the filtering bandwidth of the first filter device based on the comparison.
6. The apparatus of claim 5 wherein the variable signal reducer determining whether to remove a portion of the chrominance component signal includes determining a difference between the leakage detection signal and a first second threshold.
7. The apparatus of claim 5 wherein the entire chrominance component signal is removed.
8. The apparatus of claim 5 further comprising a variable signal adder configured to receive the leakage detection signal and to make a determination as to whether to add a portion of the received chrominance component to the received luminance component.
9. An apparatus, for use in a receiver configured to receive an electronic video signal, wherein the video signal includes a first color component that is encoded with amplitude modulation and a second color component that is encoded with frequency modulation on a carrier frequency, the apparatus comprising:
a first filter device configured to receive the video signal and output a substantial portion of the first color component as a received first color component;
a second filter device configured to receive the video signal and output a substantial portion of the second color component as a received second color component;
a leakage detector device configured to receive the carrier frequency of the second color component and output a leakage detection signal; and
a variable signal adder configured to receive the leakage detection signal and to make a determination as to whether to add a portion of the received second color component to the received first color component; and
wherein the first filter device is further configured to receive the leakage detection signal, compare the leakage detection signal to a first threshold and adjust the filtering bandwidth of the first filter device based on the comparison.
10. A method of video separation in a receiver configured to receive an electronic video signal, wherein the video signal includes a first color component that is encoded with amplitude modulation and a second color component that is encoded with frequency modulation on a carrier frequency, the method comprising:
receiving the video signal;
outputting a substantial portion of the first color component as a received first color component;
outputting a substantial portion of the second color component as a received second color component;
receiving the carrier frequency of the second color component and outputting a leakage detection signal;
receiving the leakage detection signal and making a determination as to whether to add a portion of the received second color component to the received first color component;
comparing the leakage detection signal to a first threshold; and
adjusting the filtering bandwidth of the first filter device based on the comparison.