# US 8,150,270 B2 · Compact high-speed modulator driver method and apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,150,270 B2 - Document ID: US8150270B2 - Status: Granted - Kind: B2 - Application number: 12/383,910 - Filed: 2009-03-30 - Published: 2009-10-01 - Granted: 2012-04-03 - Earliest claimed: 2008-03-31 - Assignees: Kitel Technologies LLC - Inventors: Andrew John Bonthron - Web page: https://patentgrep.com/patent/US8150270B2 ## CPC - H03F 3/607: {using FET's} - G02F 1/0327: {Operation of the cell; Circuit arrangements (G02F1/05 takes precedence)} - H03F 3/45089: {Non-folded cascode stages} - H03F 3/45475: {using IC blocks as the active amplifying circuit} - H03F 3/602: {Combinations of several amplifiers} - H03F 2203/45136: One differential amplifier in IC-block form being shown - H03F 2203/45612: the IC comprising one or more input source followers as input stages in the IC - H03F: AMPLIFIERS - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS ## Abstract Modulator driver for driving an electro-optical modulator in a high-speed optical communications system. In accordance with aspects of the present invention, a modulator driver is presented comprising an input differential limiting amplifier which is coupled to a distributed differential current-switch configuration, where one set of outputs of the distributed differential current-switch configuration are grounded and the other set of outputs are connected to an artificial transmission line structure generating forward traveling and reverse traveling signals, with the reverse traveling signal termination bias inductively coupled to a separately adjustable positive bias voltage, whereby the circuit architecture reduces the number of components and transitions in the high-speed signal path and is compatible with compact, monolithic fabrication requiring a minimal amount of external components for operation. Other methods and apparatus are presented. ## Claims ### Claim 1 A modulator driver apparatus for driving an electro-optical modulator in a high-speed optical communications system, comprising: a differential limiting input amplifier configured to generate differential output signals in response to an input signal; a distributed limiting power amplifier comprising a plurality of differential current switching stages having differential inputs inductively coupled to form differential input artificial transmission lines, said differential input artificial transmission lines DC coupled to said differential output signals from said differential limiting input amplifier; and a single-ended output artificial transmission line formed by inductively coupling one output signal from each of said differential current switching stages, the other output signal from each of said differential current switching stages being terminated, whereby the configuration of said differential limiting input amplifier and said distributed limiting power amplifier provides a compact form consistent with monolithic fabrication in an integrated circuit process. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein said differential current switching stages generate forward-traveling and reverse-traveling signals on said output artificial transmission line. ### Claim 3 (depends on 2) The apparatus of claim 2, further comprising a termination resistor for termination of said reverse-traveling signals on said output artificial transmission line. ### Claim 4 (depends on 3) The apparatus of claim 3, further comprising an inductively coupled biasing circuit connected between said output artificial transmission line and said termination resistor. ### Claim 5 (depends on 4) The apparatus of claim 4, wherein said inductively coupled biasing circuit is a bias-T. ### Claim 6 (depends on 3) The apparatus of claim 3, further comprising an inductively coupled biasing circuit connected at the output of said output artificial transmission line. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein said other output signal from each of said differential current switching stages is terminated to ground. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein said other output signal from each of said differential current switching stages is terminated to a DC voltage potential. ### Claim 9 (depends on 1) The apparatus of claim 1, wherein said input signal to said differential limiting input amplifier is differential. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein said input signal to said differential limiting input amplifier is single-ended and said differential limiting input amplifier further provides a single-ended to differential signal conversion function. ### Claim 11 (depends on 1) The apparatus of claim 1, wherein said differential current switching stages comprise transistors arranged in a differential common-emitter amplifier configuration. ### Claim 12 (depends on 1) The apparatus of claim 1, wherein said differential current switching stages comprise transistors arranged in a differential common-source amplifier configuration. ### Claim 13 (depends on 1) The apparatus of claim 1, wherein said differential current switching stages comprise transistors arranged in a differential cascode amplifier configuration. ### Claim 14 (depends on 1) The apparatus of claim 1, further comprising a plurality of said differential limiting input amplifiers and said distributed limiting power amplifiers to generate a plurality of output signals. ### Claim 15 (depends on 1) The apparatus of claim 1, wherein said integrated circuit process is a bipolar process. ### Claim 16 (depends on 1) The apparatus of claim 1, wherein said integrated circuit process is a bi-CMOS process. ### Claim 17 (depends on 1) The apparatus of claim 1, wherein said integrated circuit process is an HBT process. ### Claim 18 (depends on 1) The apparatus of claim 1, wherein said integrated circuit process is a DHBT process. ### Claim 19 (depends on 1) The apparatus of claim 1, wherein said integrated circuit process is a HEMT process. ### Claim 20 (depends on 1) The apparatus of claim 1, wherein said output artificial transmission line provides an output signal to the electro-optical modulator.