# US 10,320,488 B2 · Distributed traveling-wave Mach-Zehnder modulator driver

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- Number: US 10,320,488 B2
- Document ID: US10320488B2
- Status: Granted
- Kind: B2
- Application number: 16/220,203
- Filed: 2018-12-14
- Published: 2019-04-11
- Granted: 2019-06-11
- Earliest claimed: 2014-02-10
- Assignees: Elenion Technologies, LLC
- Applicants: Elenion Technologies, LLC
- Inventors: Ran Ding; Thomas Wetteland Baehr-Jones; Michael J. Hochberg; Alexander Rylyakov
- Web page: https://patentgrep.com/patent/US10320488B2

## CPC

- H04B 10/5561: {Digital phase modulation}
- G02F 1/0123: {Circuits for the control or stabilisation of the bias voltage, e.g. automatic bias control [ABC] feedback loops}
- G02F 1/025: in an optical waveguide structure (G02F1/017, {G02F1/2257} take precedence)
- G02F 1/2257: {the optical waveguides being made of semiconducting material}
- H04B 10/505: {using external modulation}
- H04B 10/5161: {Combination of different modulation schemes}
- H04B 10/541: {Digital intensity or amplitude modulation}
- G02F 1/212: {Mach-Zehnder type}
- G02F 2201/127: travelling wave
- H04B: TRANSMISSION
- 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

A distributed traveling-wave Mach-Zehnder modulator driver having a plurality of modulation stages that operate cooperatively (in-phase) to provide a signal suitable for use in a 100 Gb/s optical fiber transmitter at power levels that are compatible with conventional semiconductor devices and conventional semiconductor processing is described.

## Claims

### Claim 1

A driver amplifier for a distributed traveling-wave modulator comprising a plurality of driver amplifier stages, each driver amplifier stage comprising:
a differential driver amplifier input for receiving a differential input signal from a data source or a previous stage;
a first pair of emitter followers including termination resistors;
a pre-amplifier comprising a differential pair;
a buffer comprising a second pair of emitter followers;
a splitter for splitting the input signal into first and second differential output signals;
a differential driver modulator driver output for receiving the first differential output signal for driving a modulator segment; and
a differential driver signal output for amplifying the second differential output signal for providing the amplified second differential output to a subsequent driver amplifier stage.

### Claim 2 (depends on 1)

The driver amplifier according to claim 1, wherein each driver amplifier stage includes only a single type of transistor to enable high-speed operation.

### Claim 3 (depends on 1)

The driver amplifier according to claim 1, further comprising a plurality of DC bias elements for independently varying biasing voltages of individual driver amplifier stages.

### Claim 4 (depends on 3)

The driver amplifier according to claim 3, wherein each DC bias element is capable of controlling an on state and an off state of a respective driver amplifier stage for shutting down redundant driver amplifier stages.

### Claim 5 (depends on 3)

The driver amplifier according to claim 3, further comprising a delay/relay stage between driver amplifier stages for matching an optical delay between modulator segments, whereby modulations constructively add.

### Claim 6 (depends on 5)

The driver amplifier according to claim 5, wherein a plurality of the DC bias elements are configured to individually control said plurality of delay/relay stages;
wherein each DC bias element is capable of controlling an on state and an off state of a respective delay/relay stage for shutting down redundant delay/relay stages.

### Claim 7 (depends on 1)

The driver amplifier according to claim 1, further comprising a delay/relay stage between driver amplifier stages for matching an optical delay between modulator segments, whereby modulations constructively add.

### Claim 8 (depends on 7)

The driver amplifier according to claim 7, further comprising a plurality of DC bias elements, each DC bias element configured to individually control one of said plurality of delay/relay stages;
wherein each DC bias element is capable of controlling an on state and an off state of a respective delay/relay stage for shutting down redundant delay/relay stages.

### Claim 9 (depends on 7)

The driver amplifier according to claim 7, wherein the plurality of driver amplifier stages comprises four, and the number of delay/relay stages comprises three.

### Claim 10 (depends on 1)

The driver amplifier according to claim 1, wherein each output of each driver amplifier stage is configured to be an open-collector driver for driving modulator segments with different impedances.

### Claim 11 (depends on 1)

The driver amplifier according to claim 1, wherein each output of each driver amplifier stage is configured to be an open-collector cascode driver for driving modulator segments with different impedances.

### Claim 12 (depends on 1)

The driver amplifier according to claim 1, wherein each output of each driver amplifier stage is configured to be an open-collector driver for driving both 25Ω and 50Ω impedance modulator segments.

### Claim 13 (depends on 1)

The driver amplifier according to claim 1, wherein the plurality of driver amplifier stages comprises four.