# US 8,543,171 B2 · Data transmission circuit and its control method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,543,171 B2 - Document ID: US8543171B2 - Status: Granted - Kind: B2 - Application number: 12/199,298 - Filed: 2008-08-27 - Published: 2009-05-21 - Granted: 2013-09-24 - Earliest claimed: 2007-08-30 - Assignees: Fujitsu Semiconductor Limited - Applicants: Masato Tomita; Takashi Shimizu; Hideaki Watanabe - Inventors: Masato Tomita; Takashi Shimizu; Hideaki Watanabe - Web page: https://patentgrep.com/patent/US8543171B2 ## CPC - H04L 25/0264: {Arrangements for coupling to transmission lines (duplexing arrangements H04L5/14; line equalisers, line build-out devices H04L25/03878)} - H03K 5/08: by limiting; by thresholding; by slicing, i.e. combined limiting and thresholding (H03K5/07 takes precedence; comparing one pulse with another H03K5/22; providing a determined threshold for switching H03K17/30) - H04L 25/0272: {Arrangements for coupling to multiple lines, e.g. for differential transmission} - H04L 25/028: {Arrangements specific to the transmitter end} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) ## Abstract A data transmission circuit transmitting an activation signal prior to a data signal through a signal transmission line, including: an activation detection signal generation unit for generating an activation detection signal by detecting the activation signal; and a wakeup signal generation unit for being activated by the activation detection signal, and generating a wakeup signal by detecting that the activation signal is transmitted for a predetermined time. ## Claims ### Claim 1 A data transmission circuit, comprising: an activation detection signal generation unit for detecting an activation signal indicative of a data signal being transmitted through a signal transmission line, and generating an activation detection signal; and a wakeup signal generation unit for receiving the generated activation detection signal, and generating a wakeup signal by detecting that the activation signal is transmitted for a predetermined time, wherein the activation signal comprises a differential signal, and the activation detection signal generation unit comprises: a level shift unit for shifting a signal level of each of a plurality of signals configuring the differential signal to a predetermined level; and a comparison unit for comparing the activation signal shifted by the level shift unit to the predetermined level with a reference voltage. ### Claim 2 (depends on 1) The data transmission circuit according to claim 1, wherein the wakeup signal generation unit comprises: a clock signal generation unit for generating a clock signal based on the activation signal; and a wakeup signal output unit for outputting the wakeup signal by detecting that the clock signal is generated periodically for the predetermined time. ### Claim 3 (depends on 2) The data transmission circuit according to claim 2, wherein: the activation signal is a periodic signal whose signal level is alternately and repeatedly changed; and the clock signal generation unit generates the clock signal based on the periodic signal. ### Claim 4 (depends on 1) The data transmission circuit according to claim 1, wherein the level shift unit is coupled to a reference voltage generation unit for generating the reference voltage through a capacitor. ### Claim 5 (depends on 2) The data transmission circuit according to claim 2, wherein the wakeup signal output unit comprises a count unit for detecting that a clock value of the clock signal exceeds a predetermined value. ### Claim 6 (depends on 1) The data transmission circuit according to claim 1, wherein the data signal is in accordance with an IEEE1394 standard. ### Claim 7 (depends on 3) The data transmission circuit according to claim 3, wherein the activation signal is a tone signal. ### Claim 8 A method, comprising: detecting an activation signal indicative of a data signal being transmitted through a signal transmission line, wherein the activation signal comprises a differential signal; generating an activation detection signal in response to the detected activation signal, comprising: shifting a signal level of each of a plurality of signals configuring the differential signal to a predetermined level, and comparing the activation signal shifted to the predetermined level with a reference voltage; and generating a wakeup signal by receiving the generated activation detection signal and detecting that the activation signal is transmitted for a predetermined time. ### Claim 9 (depends on 8) The method according to claim 8, wherein generating the wakeup signal comprises: generating a clock signal according to the activation signal; and outputting the wakeup signal by detecting that the clock signal is generated periodically for the predetermined time. ### Claim 10 (depends on 9) The method according to claim 9, wherein the activation signal is a periodic signal whose signal level is alternately and repeatedly changed; and the clock signal is generated based on the periodic signal when the clock signal is generated. ### Claim 11 (depends on 9) The method according to claim 9, further comprising detecting that a clock value of the clock signal exceeds a predetermined value when the wakeup signal is output. ### Claim 12 (depends on 8) The method according to claim 8, wherein the data signal is in accordance with an IEEE1394 standard. ### Claim 13 (depends on 10) The method according to claim 10, wherein the activation signal is a tone signal.