# US 11,121,893 B2 · Equalizing transmitter and method of operation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,121,893 B2 - Document ID: US11121893B2 - Status: Granted - Kind: B2 - Application number: 16/685,886 - Filed: 2019-11-15 - Published: 2020-06-04 - Granted: 2021-09-14 - Earliest claimed: 2007-01-09 - Assignees: Rambus Inc. - Applicants: Rambus Inc. - Inventors: John Wood Poulton - Web page: https://patentgrep.com/patent/US11121893B2 ## CPC - H04L 25/03878: {Line equalisers; line build-out devices} - H04L 25/0272: {Arrangements for coupling to multiple lines, e.g. for differential transmission} - H04L 25/0288: {the shape being matched to the transmission line (pre-equalisation per se H04L25/03343)} - H04L 25/0282: {Provision for current-mode coupling} - H04L 25/03343: {Arrangements at the transmitter end} - H04L 2025/03808: {Transmission of equaliser coefficients} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A transmitter for providing channel equalization that includes a first driver and second driver having a high pass filter. The first driver generates a first output signal representing a digital input signal. The second driver generates a second output signal representing a high pass filtered version of the digital input signal. The first and second output signals are summed to provide a third output signal that is channel equalized for transmission over a channel. ## Claims ### Claim 1 A transmitter, comprising: a transmitter output terminal; a driver to generate a first signal representing a digital input signal at a driver output terminal; and, a passive network coupled between the driver output terminal and the transmitter output terminal to generate a second signal at the transmitter output terminal, the second signal to be a combination of an unfiltered and attenuated version of the first signal and a high pass resistor-capacitor (RC) network filtered version of the first signal. ### Claim 2 (depends on 1) The transmitter of claim 1, wherein the passive network comprises: a first current path to generate the unfiltered and attenuated version of the first signal. ### Claim 3 (depends on 2) The transmitter of claim 2, wherein the passive network further comprises: a second current path to generate the high pass resistor-capacitor (RC) network filtered version. ### Claim 4 (depends on 3) The transmitter of claim 3, wherein the second current path generates current spikes corresponding to each transition of the driver output terminal. ### Claim 5 (depends on 4) The transmitter of claim 4, wherein the passive network has at least an adjustable frequency cutoff that determines at least a rate of a gradual decay of said current spikes. ### Claim 6 (depends on 1) The transmitter of claim 1, wherein the passive network has at least an adjustable gain. ### Claim 7 (depends on 4) The transmitter of claim 4, wherein the passive network has at least an adjustable frequency cutoff that determines at least a rate of a gradual decay of said current spikes and an adjustable gain. ### Claim 8 A transmitter, comprising: a driver circuit to generate a first signal representing a digital input signal at a driver output terminal; and, a passive network having an unfiltered DC current path and a high frequency current path between a transmitter output terminal and the driver output terminal, the high frequency current path including a high pass resistor-capacitor (RC) filter network. ### Claim 9 (depends on 8) The transmitter of claim 8, wherein the high frequency current path comprises a plurality of high pass filters that are selectively enabled and disabled to provide at least an adjustable high frequency cutoff of the high frequency current path. ### Claim 10 (depends on 8) The transmitter of claim 8, wherein the high frequency current path comprises a plurality of high pass filters that are selectively enabled and disabled to provide at least an adjustable gain of the high frequency current path. ### Claim 11 (depends on 8) The transmitter of claim 8, wherein the unfiltered DC current path comprises an adjustable resistance to provide at least an adjustable gain of the unfiltered DC current path. ### Claim 12 (depends on 8) The transmitter of claim 8, wherein the transmitter output terminal is to drive one of a differential output signal pair. ### Claim 13 (depends on 8) The transmitter of claim 8, wherein the transmitter output terminal is to drive single-ended output signal. ### Claim 14 (depends on 8) The transmitter of claim 8, wherein the high frequency current path generates current spikes corresponding to each transition of the driver output terminal. ### Claim 15 (depends on 14) The transmitter of claim 14, wherein the high frequency current path has at least an adjustable frequency cutoff that determines at least a rate of a gradual decay of said current spikes. ### Claim 16 A method, comprising: generating a first signal representing a digital input signal at a driver output terminal; and, generating, by a passive network coupled between the driver output terminal and a transmitter output terminal, a second signal at the transmitter output terminal, the second signal to be a combination of an unfiltered and attenuated version of the first signal and a high pass resistor-capacitor (RC) network filtered version of the first signal. ### Claim 17 (depends on 16) The method of claim 16, wherein the passive network includes a plurality of high pass filters that are configured to be selectively enabled and disabled. ### Claim 18 (depends on 17) The method of claim 17, further comprising: enabling at least one of the plurality of high pass filters to adjust at least a frequency cutoff. ### Claim 19 (depends on 17) The method of claim 17, wherein the passive network has a frequency attenuation and the method further comprises: enabling at least one of the plurality of high pass filters to offset at least a portion of the frequency attenuation. ### Claim 20 (depends on 17) The method of claim 17, wherein the plurality of high pass filters comprise respective resistor-capacitor networks having different cutoff frequencies.