APPARATUS FOR SOURCE-SYNCHRONOUS INFORMATION TRANSFER AND ASSOCIATED METHODS
An apparatus includes an interface circuit coupled to an electronic device. The interface circuit provides source synchronous communication with the electronic device using a strobe signal. The interface circuit is configured to gate the strobe signal in order to successfully communicate with the electronic device.
1 . An apparatus, comprising an interface circuit coupled to an electronic device for source synchronous communication with the electronic device using a strobe signal, the interface circuit configured to gate the strobe signal in order to successfully communicate with the electronic device.
2 . The apparatus according to claim 1 , wherein the interface circuit increases a timing margin by increasing an amount of time for gating the strobe signal in a postamble window by minimizing a logic delay of a gating path through the interface circuit.
3 . The apparatus according to claim 1 , wherein the interface circuit independently places rising and falling edges of an enable signal for the strobe signal in respective timing windows.
4 . The apparatus according to claim 1 , wherein the interface circuit adjusts ungating and gating times of the strobe signal as a function of one or more samples of the strobe signal.
5 . The apparatus according to claim 1 , wherein the interface circuit increases a timing margin by increasing an effective preamble window of the strobe signal.
6 . The apparatus according to claim 1 , wherein the interface circuit increases a timing margin by adjusting a phase of an enable signal for the strobe signal depending on characteristics of the electronic device.
7 . The apparatus according to claim 1 , wherein the electronic device comprises a memory.
8 . The apparatus according to claim 7 , wherein the memory comprises multiple ranks.
9 . An electronic apparatus, comprising:
an electronic device that uses a strobe signal to communicate in a source synchronous manner; and
an interface circuit coupled to the electronic device to receive the strobe signal, the interface circuit configured to gate the strobe signal to provide a gated strobe signal so as to increase reliability of communication with the electronic device.
10 . The electronic apparatus according to claim 9 , further comprising a capture register that uses the gated strobe signal to receive data from the electronic device.
11 . The apparatus according to claim 9 , wherein the interface circuit comprises a shift circuit that shifts an enable signal associated with the strobe signal to generate a shifted enable signal.
12 . The electronic apparatus according to claim 11 , wherein the interface circuit further comprises a logic gate coupled to receive the strobe signal as a first input and to provide the gated strobe signal as an output.
13 . The electronic apparatus according to claim 12 , wherein the interface circuit further comprises a register clocked by the strobe signal.
14 . The electronic apparatus according to claim 13 , wherein the logic gate is coupled to accept an output signal of the register as a second input.
15 . The electronic apparatus according to claim 14 , wherein the logic gate comprises a NAND gate.
16 . The electronic apparatus according to claim 13 , wherein an asynchronous set input of the register is coupled to the shifted enable signal.
17 . The electronic apparatus according to claim 11 , wherein the interface circuit further comprises a second logic gate coupled to receive the enable signal as a first input and a configuration bit as a second input, wherein an output of the second logic gate is coupled to the input of the shift circuit.
18 . The electronic apparatus according to claim 14 , wherein the register has an optimized clock-to-output (TCO) delay.
19 . The electronic apparatus according to claim 16 , wherein a falling edge of the enable signal is delayed.
20 . The electronic apparatus according to claim 16 , wherein the interface circuit further comprises a third logic gate coupled to receive the output of the register as a first input, to receive the output of the shift circuit as a second input, and to provide an output signal to the second input of the first logic gate.
21 . The electronic apparatus according to claim 11 , wherein the interface circuit adjusts a phase of the shifted enable signal based on a variation of the strobe signal because of temperature variation and/or voltage variation.
22 . The electronic apparatus according to claim 11 , wherein the interface circuit adjusts a phase of the shifted enable signal based on one or more samples of the strobe signal.
23 . The electronic apparatus according to claim 22 , wherein the interface circuit re-interprets the one or more samples based on age of the one or more samples and/or intervening phase adjustments of the shifted enable signal.
24 . The electronic apparatus according to claim 22 , wherein the interface circuit obtains the one or more samples during source synchronous communication with the electronic device.
25 . The electronic apparatus according to claim 9 , wherein the interface circuit extends an effective preamble time of the strobe signal by creating a trigger pulse, as a function of the strobe signal and an enable signal, that is used to ungate a delayed strobe signal.
26 . The electronic apparatus according to claim 9 , wherein the interface circuit processes the gated strobe signal to remove one or more spurious edges.
27 . The electronic apparatus according to claim 11 , wherein the interface circuit is configured to communicate with a plurality of electronic devices in a source synchronous manner, wherein each electronic device in the plurality of electronic devices has a corresponding strobe signal in a plurality of strobe signals, and the interface circuit uses a corresponding enable signal shift based on information in a storage circuit that indicates with which of the plurality of logic devices the interface circuit is communicating.
28 . The electronic apparatus according to claim 11 , wherein the interface circuit further comprises:
a first storage circuit that stores information for adjusting the gating of the strobe; and
a second storage circuit that stores information for adjusting the ungating of the strobe.
29 . The electronic apparatus according to claim 27 , wherein the storage circuit is clocked by the enable signal.
30 . The electronic apparatus according to claim 11 , wherein the interface circuit further comprises programmable inverters coupled to, respectively, inputs and outputs of the shift circuit.
31 . A method of providing source synchronous communication in a logic circuit, the method comprising:
receiving a strobe signal; and
gating the strobe signal so as to successfully provide source synchronous communication.
32 . The method according to claim 31 , wherein the strobe signal comprises a postamble window, and wherein gating the strobe signal further comprises increasing an amount of time for gating the strobe signal in the postamble window by minimizing a logic delay of a gating path.
33 . The method according to claim 31 , wherein gating the strobe signal further comprises:
using an enable signal; and
independently placing rising and falling edges of the enable signal in respective timing windows.
34 . The method according to claim 31 , wherein gating the strobe signal further comprises adjusting ungating and gating times of the strobe signal as a function of one or more samples of the strobe signal.
35 . The method according to claim 31 , wherein the strobe signal comprises a preamble window, and wherein gating the strobe signal further comprises increasing an effective preamble window of the strobe signal.
36 . The method according to claim 31 , wherein providing source synchronous communication further comprises communicating with a memory device.
37 . The method according to claim 36 , wherein the memory device comprises a plurality of ranks.
38 . The method according to claim 37 , wherein each rank in the plurality of ranks has a corresponding strobe signal in a plurality of strobe signals.
39 . The method according to claim 38 , wherein each strobe signal in the plurality of strobe signals has a corresponding enable signal shift in a plurality of enable signal shifts.
40 . The method according to claim 39 , wherein gating the strobe signal comprises:
storing a phase shift for the enable signal corresponding to the strobe signal that corresponds to each rank in the plurality of ranks; and
communicating with at least one rank by using the phase shift corresponding to the enable signal that corresponds to the at least one rank.