# US 10,320,496 B2 · Periodic calibration for communication channels by drift tracking > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,320,496 B2 - Document ID: US10320496B2 - Status: Granted - Kind: B2 - Application number: 15/490,627 - Filed: 2017-04-18 - Published: 2017-11-02 - Granted: 2019-06-11 - Earliest claimed: 2004-01-28 - Assignees: Rambus Inc. - Applicants: Rambus Inc. - Inventors: Craig E. Hampel; Frederick A. Ware; Richard E. Perego - Web page: https://patentgrep.com/patent/US10320496B2 ## CPC - H04B 17/11: for calibration - H04B 17/00: Monitoring; Testing (of line transmission systems H04B3/46; arrangements for monitoring or testing transmission systems employing electromagnetic waves other than radio waves H04B10/07) - H04B 17/22: {for calibration of the receiver components} - H04L 7/0004: {Initialisation of the receiver (H04L7/0075 and H04L7/10 take precedence)} - H04L 7/0016: {correction of synchronization errors} - H04L 7/0087: {Preprocessing of received signal for synchronisation, e.g. by code conversion, pulse generation or edge detection} - H04L 7/043: {Pseudo-noise [PN] codes variable during transmission (synchronisation of spread spectrum receivers H04B1/69)} - H04L 7/10: Arrangements for initial synchronisation - H04L 27/00: Modulated-carrier systems - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A method and system that provides for execution of a first calibration sequence, such as upon initialization of a system, to establish an operation value, which utilizes an algorithm intended to be exhaustive, and executing a second calibration sequence from time to time, to measure drift in the parameter, and to update the operation value in response to the measured drift. The second calibration sequence utilizes less resources of the communication channel than does the first calibration sequence. In one embodiment, the first calibration sequence for measurement and convergence on the operation value utilizes long calibration patterns, such as codes that are greater than 30 bytes, or pseudorandom bit sequences having lengths of 2N−1 bits, where N is equal to or greater than 7, while the second calibration sequence utilizes short calibration patterns, such as fixed codes less than 16 bytes, and for example as short as 2 bytes long. ## Claims ### Claim 1 A method of calibrating a component having a circuit that is to exchange bits of data via a communications link, the method comprising: performing a first calibration of the component during an initialization process, the first calibration to establish an initial value for at least one parameter pertaining to driver strength and termination resistance and affecting the exchange of the bits of data by the circuit; and performing, at occurrence of each of predetermined events, a second calibration of the component to update the value for the at least one parameter, wherein the second calibrations are each to occur during a time period that is shorter than a time period of the first calibration. ### Claim 2 (depends on 1) The method of claim 1, wherein the predetermined events comprise an event detected in response to a timer. ### Claim 3 (depends on 1) The method of claim 1, wherein the predetermined events comprise a detected change in a drift condition. ### Claim 4 (depends on 1) The method of claim 1, wherein the predetermined events comprise a detected change in temperature. ### Claim 5 (depends on 1) The method of claim 1, wherein performing the first calibration comprises receiving a first pattern and comparing the first pattern with a first expected pattern, and wherein performing the second calibration comprises receiving a second pattern and comparing the second pattern with a second expected pattern. ### Claim 6 (depends on 1) The method of claim 1, wherein performing the first calibration comprises receiving a first calibration sequence of at least one pattern and comparing each pattern in the first calibration sequence with an expected pattern, and wherein performing the second calibration comprises receiving a second calibration sequence of at least one pattern and comparing each pattern in the second series with an expected pattern. ### Claim 7 (depends on 1) The method of claim 1, wherein performing the first calibration comprises transmitting a first pattern and comparing the first received pattern based on the first pattern with a first expected pattern, and wherein performing the second calibration comprises transmitting a second pattern and comparing a second received pattern based on the second pattern with a second expected pattern. ### Claim 8 (depends on 1) The method of claim 1, wherein performing the first calibration comprises transmitting a first calibration sequence of at least one pattern and comparing a received sequence based on the first calibration sequence with at least one expected pattern, and wherein performing the second calibration comprises transmitting a second calibration sequence of at least one pattern and comparing a received sequence based on the second calibration sequence with at least one expected pattern. ### Claim 9 (depends on 8) The method of claim 8, wherein each pattern of the at least one pattern of the second calibration sequence is two bytes or less in length, and wherein each pattern of the at least one pattern of the first calibration sequence is greater than two bytes in length. ### Claim 10 An apparatus to calibrate a component having a circuit that is to exchange bits of data via a communications link, the apparatus comprising: means for performing a first calibration of the component during an initialization process, the first calibration to establish an initial value for at least one parameter pertaining to driver strength and termination resistance and affecting the exchange of the bits of data by the circuit; and means for performing, at occurrence of each of predetermined events, a second calibration of the component to update the value for the at least one parameter, wherein the second calibrations are each to occur during a time period that is shorter than a time period of the first calibration. ### Claim 11 An apparatus to calibrate a component having a circuit that is to exchange bits of data via a communications link, the apparatus comprising: circuitry to perform a first calibration of the component during an initialization process, the first calibration to establish an initial value for at least one parameter pertaining to driver strength and termination resistance and affecting the exchange of the bits of data by the circuit; and circuitry to perform, at occurrence of each of predetermined events, a second calibration of the component to update the value for the at least one parameter, wherein the second calibrations are each to occur during a time period that is shorter than a time period of the first calibration. ### Claim 12 (depends on 11) The apparatus of claim 11, wherein the predetermined events comprise an event detected in response to a timer. ### Claim 13 (depends on 11) The apparatus of claim 11, wherein the predetermined events comprise a detected change in a drift condition. ### Claim 14 (depends on 11) The apparatus of claim 11, wherein the predetermined events comprise a detected change in temperature. ### Claim 15 (depends on 11) The apparatus of claim 11, wherein the circuitry to perform the first calibration comprises circuitry to receive a first pattern and to compare the first pattern with a first expected pattern, and wherein the circuitry to perform the second calibration comprises circuitry to receive a second pattern and to compare the second pattern with a second expected pattern. ### Claim 16 (depends on 11) The apparatus of claim 11, wherein the circuitry to perform the first calibration comprises circuitry to receive a first calibration sequence of at least one pattern and to compare each pattern in the first calibration sequence with an expected pattern, and wherein the circuitry to perform the second calibration comprises circuitry to receive a second calibration sequence of at least one pattern and to compare each pattern in the second series with an expected pattern. ### Claim 17 (depends on 11) The apparatus of claim 11, wherein the circuitry to perform the first calibration comprises circuitry to transmit a first pattern and to compare a received pattern based on the first pattern with a first expected pattern, and wherein the circuitry to perform the second calibration comprises circuitry to transmit a second pattern and to compare a received pattern based on the second pattern with a second expected pattern. ### Claim 18 (depends on 11) The apparatus of claim 11, wherein the circuitry to perform the first calibration comprises circuitry to transmit a first calibration sequence of at least one pattern and to compare a received sequence based on the first calibration sequence with at least one expected pattern, and wherein the circuitry to perform the second calibration comprises circuitry to transmit a second calibration sequence of at least one pattern and to compare a received sequence based on the second calibration pattern with at least one expected pattern. ### Claim 19 (depends on 18) The apparatus of claim 18, wherein each pattern of the at least one pattern of the second calibration sequence is two bytes or less in length, and wherein each pattern of the at least one pattern of the first calibration sequence is greater than two bytes in length.