Resynchronization of a clock associated with each data bit in a double data rate memory system
View Patent ↗An apparatus comprising an input interface, an output interface and an adjustment circuit. The input interface may comprise a plurality of input stages each configured to receive a data signal and a clock signal and present an intermediate signal. The output interface may comprise a plurality of output stages each configured to receive the intermediate signal, receive an adjusted clock signal and present an output signal. The adjustment circuit may comprise a plurality of adjustment components each configured to (i) receive the clock signal and (ii) present the adjusted clock signal. The clock signal may be presented through a clock tree. The adjustment circuit may be located near the output interface. The adjustment circuit may be configured to resynchronize the clock signal for each bit transmitted to reduce a mismatch between a bit to bit delay and a delay caused by the clock tree.
1. An apparatus comprising:
an input interface comprising a plurality of input stages each configured to (i) receive (a) a data signal and (b) a clock signal through a first clock tree and (ii) present an intermediate signal;
an output interface comprising a plurality of output stages each configured to (i) receive said intermediate signal from one of said input stages, (ii) receive an adjusted clock signal and (iii) present an output signal; and
an adjustment circuit comprising a plurality of adjustment components each configured to (i) receive said clock signal through a second clock tree, (ii) receive a reference clock signal, and (iii) generate said adjusted clock signals presented to each of said output stages, wherein (a) said adjustment circuit is located near said output interface, and (b) each of said adjustment components is configured to resynchronize said clock signal for each respective bit transmitted from said input interface to said output interface to reduce a bit to bit delay caused by said clock tree.
2. The apparatus according to claim 1 , wherein said apparatus is implemented in a register clock driver.
3. The apparatus according to claim 1 , wherein said apparatus is implemented in a data buffer.
4. The apparatus according to claim 1 , wherein said adjustment components are implemented as at least one of (a) phase-locked loop circuits and (b) delay-locked loop circuits.
5. The apparatus according to claim 4 , wherein a fabrication size of said adjustment components enables one of said adjustment components to be placed next to each of said output stages of said output interface.
6. The apparatus according to claim 5 , wherein said fabrication size is in a range of 28 nm to 65 nm.
7. The apparatus according to claim 4 , wherein each of said adjustment components is further configured to receive said reference clock signal through a delay circuit.
8. The apparatus according to claim 4 , wherein said adjustment components are designed without an embedded low-dropout regulator.
9. The apparatus according to claim 1 , wherein said adjustment circuit is configured to adjust at least one of (a) jitter and (b) skew through at least one of a clock line and said clock tree.
10. The apparatus according to claim 1 , wherein (i) said output stages are grouped into a plurality of output stage groups and (ii) said adjustment components are configured to synchronize one of said output stage groups with another of said output stage groups.
11. The apparatus according to claim 10 , wherein said plurality of adjustment components are configured to adjust a variation between said output stage groups at distant locations from each other.
12. The apparatus according to claim 11 , wherein said variation between said output stages within one of said output stage groups is negligible compared to said variation between said output stage groups at said distant locations from each other.
13. The apparatus according to claim 1 , wherein said adjustment components comprise a phase adjuster.
14. The apparatus according to claim 13 , wherein said adjustment circuit further comprises a feedback integrator loop configured to force a synchronization of said output interface.
15. The apparatus according to claim 13 , wherein said adjustment circuit implements a master-slave structure for group synchronization when a number of said output stages is greater than two.
16. The apparatus according to claim 1 , wherein said apparatus is configured to implement resynchronization of each data bit in a double data rate (DDR) memory system.
17. The apparatus according to claim 1 , wherein said adjustment components are implemented using FinFET technology.
18. The apparatus according to claim 1 , wherein each of said adjustment components comprises a phase locked loop configured to generate said adjusted clock signal for each bit based on a comparison between said clock signal and said reference clock signal.