CN118786625A

CN118786625A - Driver amplifier for optical transmitter and optical transmitter for optical communication

Info

Publication number: CN118786625A
Application number: CN202280092767.4A
Authority: CN
Inventors: 卢卡·皮亚宗; 安东尼奥·穆西奥
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2022-03-03
Filing date: 2022-03-03
Publication date: 2024-10-15
Also published as: WO2023165699A1

Abstract

There is provided a driver amplifier for an optical transmitter, the driver amplifier comprising a first amplifier channel and a second amplifier channel, each amplifier channel for amplifying a respective radio frequency channel signal. The first and second amplifier channels each include a Direct Current (DC) bias point. The driver amplifier further includes a common bias line interconnecting the DC bias point of the first amplifier channel and the DC bias point of the second amplifier channel. The driver amplifier further includes a ground node and a shunt capacitor connected between the common bias line and the ground node through one or more vias. The first and second amplifier channels are arranged symmetrically to each other on both sides of a plane of symmetry, and the parallel capacitor is placed on the plane of symmetry. The shunt capacitor facilitates directly reducing inter-channel crosstalk inside the driver amplifier without increasing the data rate and power consumption of the optical transmitter.

Description

Driving amplifier for optical transmitter and optical transmitter for optical communication

Technical Field

The present invention relates generally to the field of ultra-wideband multi-channel amplifiers for optical communications, and more particularly to a drive amplifier for an optical transmitter and an optical transmitter for optical communications.

Background

Optical communications typically use light as a medium to transmit signals from a source to a destination through an optical fiber. In addition, optical transmitters are used for high-speed optical communications by cascading digital sources, driver amplifiers and electro-optic modulators. Conventional driver amplifiers are used to increase the power level of a digital signal (e.g., an electrical signal) generated by a digital source in order to provide an appropriate power supply to an electro-optic modulator. In addition, electro-optic modulators are used to convert (i.e., transform) electrical signals into optical signals that are transmitted through optical fibers. Each component (i.e., digital source, driver amplifier, and electro-optic modulator) integrates multiple channels to increase the data rate of the optical transmitter. In addition, the use of multiple channels increases inter-channel crosstalk. The inter-channel crosstalk behaves like additive noise and reduces the overall quality of the output signal, thereby further limiting the data rate of the optical transmitter.

In general, conventional optical transmitters have been proposed to eliminate or reduce inter-channel crosstalk by implementing digital cancellation functions in high-speed digital sources. In addition, an inverse crosstalk signal is added to the input signal of each channel to cancel the inter-channel crosstalk from the other channels. The data rate of the optical transmitter is still not ideal and the power consumption of the conventional optical transmitter increases because the crosstalk digital cancellation function requires additional digital blocks to implement. Therefore, there is a technical problem of how to directly reduce the crosstalk between the high frequency channels on the driver amplifier to achieve maximum data rate capability of the optical transmitter while minimizing power consumption.

Thus, in light of the foregoing discussion, there is a need to overcome the aforementioned drawbacks associated with conventional light emitters.

Disclosure of Invention

The invention provides a drive amplifier for an optical transmitter and an optical transmitter for optical communication. The present invention provides a solution to the existing problem of directly reducing the high frequency inter-channel crosstalk on the driver amplifier to achieve maximum data rate capability of the optical transmitter while minimizing power consumption. It is an object of the present invention to provide a solution which at least partly overcomes the problems encountered in the prior art and to provide an improved driving amplifier for an optical transmitter and an improved optical transmitter for optical communication to reduce high frequency inter-channel crosstalk for optical communication.

One or more of the objects of the invention are achieved by the solution provided in the attached independent claims. Advantageous implementations of the invention are further defined in the dependent claims.

In one aspect, the present invention provides a driver amplifier for an optical transmitter, the driver amplifier comprising a first amplifier channel and a second amplifier channel, each for amplifying a respective Radio Frequency (RF) channel signal, the first and second amplifier channels each having a Direct Current (DC) bias point. The driver amplifier further includes a common bias line interconnecting the DC bias point of the first amplifier channel with the DC bias point of the second amplifier. The driver amplifier further includes a ground node. The driver amplifier further includes a shunt capacitor connected between the common bias line and the ground node through one or more vias. The first and second amplifier channels are arranged symmetrically to each other on both sides of a plane of symmetry, and the parallel capacitor is placed on the plane of symmetry.

The plane of symmetry is the plane of symmetry of the first amplifier channel and the second amplifier channel. That is, geometrically reflecting the first amplifier channel through the plane of symmetry geometrically transforms any portion of the first amplifier channel into a portion of the second amplifier channel and vice versa. The driver amplifier as a whole need not be symmetrical with respect to the symmetry plane of the first and second amplifiers.

The driving amplifier of the optical transmitter includes a first amplifier channel and a second amplifier channel for amplifying corresponding Radio Frequency (RF) channel signals. The first and second amplifier channels each have a Direct Current (DC) bias point that further maximizes the available data rate of the optical transmitter. In addition, arranging the shunt capacitor between the common bias line and the ground node through one or more vias directly reduces inter-channel crosstalk within the driver amplifier without increasing the data rate and power consumption of the optical transmitter.

In one implementation, the parallel capacitor is connected at a midpoint of the common bias line between the first and second amplifier channels.

The shunt capacitor connected at the midpoint of the common bias line between the first and second amplifier channels does not affect the performance of the driver amplifier, such as power consumption, bandwidth, gain, output and input return loss, linearity, design complexity and bias. In addition, the shunt capacitor provides maximum data rate and reduces inter-channel crosstalk.

In another implementation, one or more of the vias are included within the area of the shunt capacitor.

By using one or more vias in the region of the shunt capacitor, high frequency inter-channel crosstalk can be reduced.

In another implementation, one or more of the vias are outside the area of the shunt capacitor.

In such an implementation, the number of vias provides a selection of frequency ranges within which inter-channel crosstalk is further reduced.

In another implementation, each of the amplifier channels is a wideband amplifier.

In such an implementation, the wideband amplifier delivers the required bias voltage to each amplifier channel.

In another implementation, the drive amplifier further includes a resistor disposed between each parallel capacitor and the common bias line.

In such an implementation, adding a resistor disposed between each of the parallel capacitors reduces high quality resonance.

In another aspect, the present invention provides an optical transmitter for optical communications, the optical transmitter comprising a digital source including a first source channel and a second source channel, each source channel for generating a respective Radio Frequency (RF) channel signal. The optical transmitter further includes a drive amplifier and an electro-optic modulator including a first modulator channel and a second modulator channel, each modulator channel for converting a corresponding Radio Frequency (RF) channel signal into an optical channel signal.

An optical transmitter for optical communication achieves all the advantages and technical effects of the drive amplifier of the present invention.

It should be appreciated that all of the above implementations may be combined. It should be noted that all devices, elements, circuits, units and means described in the present application may be implemented by software or hardware elements or any type of combination thereof. All steps performed by the various entities described in the present application and functions to be performed by the various entities described are intended to mean that the respective entities are adapted to perform the respective steps and functions. Although in the following description of specific embodiments, a specific function or step performed by an external entity is not reflected in the description of a specific detailed element of the entity performing the specific step or function, it should be clear to a skilled person that the methods and functions may be implemented in corresponding software or hardware elements or any combination thereof. It will be appreciated that features of the application are susceptible to being combined in various combinations without departing from the scope of the application as defined by the accompanying claims.

Additional aspects, advantages, features and objects of the invention will become apparent from the accompanying drawings and detailed description of illustrative implementations which are explained in connection with the following appended claims.

Drawings

The foregoing summary, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings exemplary constructions of the invention. The invention is not limited to the specific methods and instrumentalities disclosed herein. Moreover, it will be appreciated by those skilled in the art that the drawings are not to scale. Wherever possible, like elements are designated by like numerals.

Embodiments of the invention will now be described, by way of example only, with reference to the following drawings, in which:

FIG. 1A is a diagram of a driver amplifier provided by one embodiment of the present invention;

FIG. 1B is a schematic representation of a driver amplifier provided by another embodiment of the present invention;

FIGS. 1C and 1D are different illustrations of a driver amplifier including a first amplifier channel and a second amplifier channel according to different embodiments of the invention;

Fig. 2 is a block diagram of a light emitter provided by one embodiment of the present invention.

In the drawings, the underlined numbers are used to denote items where the underlined numbers are located or items adjacent to the underlined numbers. The non-underlined numbers are associated with items identified by lines associating the non-underlined numbers with the items. When a number is not underlined and has an associated arrow, the number without the underline is used to identify the general item to which the arrow points.

Detailed Description

The following detailed description illustrates embodiments of the invention and the manner in which the embodiments may be implemented. While some modes for carrying out the invention have been disclosed, those skilled in the art will recognize that other embodiments for carrying out or practicing the invention may also exist.

Fig. 1A is a diagram depicting a drive amplifier provided by one embodiment of the invention. Referring to fig. 1A, a diagram 100A of a driver amplifier 102 is shown, the driver amplifier 102 including a first amplifier channel 104A, a second amplifier channel 104B, a common bias line 106, a shunt capacitor 108, one or more vias 110A-110N, and a bias pad 112. It should be appreciated that in fig. 1A, the area of the shunt capacitor 108 is depicted using a rounded rectangle with a dashed line. Similarly, a region including one or more vias 110A-110N is depicted using a rounded rectangle with planar lines.

The driver amplifier 102 for an optical transmitter includes a first amplifier channel 104A and a second amplifier channel 104B, each for amplifying and increasing the power level of a corresponding Radio Frequency (RF) channel signal for optical communication.

The first amplifier channel 104A and the second amplifier channel 104B are used to amplify corresponding Radio Frequency (RF) channel signals. For example, the first amplifier channel 104A of the driver amplifier 102 is used to amplify a Radio Frequency (RF) channel signal of the input signal (IN 1) and produce an amplified output (OUT 1). Similarly, the second amplifier channel 104B of the driver amplifier 102 is used to multiply and amplify a Radio Frequency (RF) channel signal of another input signal (IN 2) and produce an amplified output (OUT 2). The first and second amplifier channels 104A, 104B have Direct Current (DC) bias points. In one implementation, the driver amplifier 102 includes more than two amplifier channels. In one example, the driver amplifier 102 includes three amplifier channels. In another example, the driver amplifier 102 includes four amplifier channels.

The common bias line 106 is used to interconnect the DC bias point of the first amplifier channel 104A with the DC bias point of the second amplifier channel 104B. In one example, the common bias line 106 is used to deliver the required bias voltages to the first and second amplifier channels 104A, 104B (or to each amplifier stage).

The shunt capacitor 108 is connected between the common bias line 106 and the ground node through one or more vias 110A-110N.

Each of the one or more vias 110A-110N may also be referred to as a trench, opening, or hole. In one example, one or more vias 110A-110N are formed by standard photolithographic or etching techniques.

A drive amplifier 102 for a light emitter is provided. The driver amplifier 102 includes a first amplifier channel 104A and a second amplifier channel 104B. Each amplifier channel is used to amplify a power level of a corresponding Radio Frequency (RF) channel signal. IN one example, the first amplifier channel 104A amplifies a corresponding Radio Frequency (RF) channel signal (or power level), such as an RF channel signal of the input signal (IN 1), and also generates an amplified output (OUT 1). Similarly, the second amplifier channel 104B amplifies a corresponding RF channel signal (or power level), e.g., an RF channel signal of the input signal (IN 2), and produces an amplified output (OUT 2). In one example, the driver amplifier 102 includes more than two amplifier channels, such as three amplifier channels or four amplifier channels. The first and second amplifier channels 104A, 104B have Direct Current (DC) bias points. The driver amplifier 102 further comprises a common bias line 106, which common bias line 106 is arranged to interconnect the DC bias point of the first amplifier channel 104A with the DC bias point of the second amplifier channel 104B. In one example, the common bias line 106 communicates a desired bias voltage to the first amplifier channel 104A and the second amplifier channel 104B. The first amplifier channel 104A and the second amplifier channel 104B are symmetrically arranged to each other on both sides of the symmetry plane A-A, and the parallel capacitor 108 is placed on the symmetry plane A-A. In other words, the shunt capacitor 108 is placed on the symmetry plane A-A, and the first amplifier channel 104A is arranged on one side of the symmetry plane A-A. Furthermore, the second amplifier channel 104B is arranged on the other side of the symmetry plane A-A, for example symmetrically to the first amplifier channel 104A, as shown in fig. 1A and 1B. According to one embodiment, each of the amplifier channels is a wideband amplifier. A wideband amplifier corresponds to an amplifier having a precise amplification factor over a wide frequency range. A wideband amplifier is advantageous for boosting the channel signal and also for providing an amplified signal.

The driver amplifier 102 further includes a ground node and a shunt capacitor 108, the shunt capacitor 108 being connected between the common bias line 106 and the ground node through one or more vias 110A-110N. For example, the shunt capacitor 108 is connected between the common bias line 106 and a ground node (not shown in fig. 1A) through one or more vias 110A-110N.

The shunt capacitor 108 facilitates directly reducing inter-channel crosstalk within the driver amplifier 102 without affecting source data rate, power consumption, bandwidth, gain, output and input return loss, linearity, design complexity. For example, the shunt capacitor 108 reduces crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. Thus, the driver amplifier 102 supports increasing (or maximizing) the available data rate of the optical transmitter.

According to one embodiment, the shunt capacitor 108 is connected at the midpoint of the common bias line 106 between the first and second amplifier channels 104A, 104B. Advantageously, the arrangement of the shunt capacitor 108 between the first and second amplifier channels 104A, 104B reduces high frequency inter-channel crosstalk in the driver amplifier 102 compared to conventional amplifiers.

In one implementation, the length and width of the shunt capacitor 108 are selected to tune a frequency range in which cross-talk between the first and second amplifier channels 104A, 104B is reduced. In one example, the length of the shunt capacitor 108 is referred to as L _CAP and the width of the shunt capacitor 108 is referred to as W _CAP, as shown in fig. 1A. In addition, the length and width of the shunt capacitor 108 are optimized to tune the frequency range in which crosstalk between the first and second amplifier channels 104A, 104B is reduced. In one example, the length of the shunt capacitor 108 is increased without changing the width of the shunt capacitor 108 to tune the frequency range in which crosstalk between the first and second amplifier channels 104A, 104B is reduced. Similarly, the length of the shunt capacitor 108 may be reduced without changing the width of the shunt capacitor 108 to tune the frequency range in which cross-talk between the first and second amplifier channels 104A, 104B is reduced. In another example, the width of the shunt capacitor 108 is increased without changing the length of the shunt capacitor 108 to tune a frequency range in which cross-talk between adjacent amplifier channels is reduced. Similarly, the width of the shunt capacitor 108 may be reduced without changing the length of the shunt capacitor 108 to tune the frequency range in which cross-talk between the first and second amplifier channels 104A, 104B is reduced. In yet another example, the length and width of the shunt capacitor 108 is increased to tune a frequency range in which cross-talk between adjacent amplifier channels is reduced. Similarly, the length of the shunt capacitor 108 and the width of the shunt capacitor 108 may be reduced simultaneously to tune the frequency range in which cross-talk between the first and second amplifier channels 104A, 104B is reduced.

According to one embodiment, one or more of vias 110A-110N are included within the area of shunt capacitor 108. In one implementation, the shunt capacitor 108 is disposed between the first amplifier channel 104A and the second amplifier channel 104B. Further, one or more of the vias 110A to 110N are included in the area of the shunt capacitor 108. For example, the shunt capacitor 108 disposed between the first amplifier channel 104A and the second amplifier channel 104B includes a via 110A and a via 110B. In one implementation, the number of vias in the region of the shunt capacitor 108 is selected to tune the frequency range in which crosstalk between the first and second amplifier channels 104A, 104B is reduced. In one example, the number of vias in the region of shunt capacitor 108 is greater than zero, e.g., vias 110A and 110B are included in the region of shunt capacitor 108. In another example, the number of vias in the region of the shunt capacitor 108 is zero. Advantageously, the number of vias in the region of the shunt capacitor 108 enables the shunt capacitor 108 to tune a frequency range in which crosstalk between the first and second amplifier channels 104A, 104B is reduced.

According to one embodiment, one or more of the vias 110A-110N are arranged outside the area of the shunt capacitor 108. In one example, the shunt capacitor 108 is disposed between the common bias line 106 and the ground node through one or more vias 110A-110N. Further, one or more of the vias 110A-110N are included outside the area of the shunt capacitor 108. For example, the shunt capacitor 108 is disposed between the common bias line 106 and the ground node, and the via 110N is disposed outside the area of the shunt capacitor 108, as shown in fig. 1A.

According to one embodiment, the number of vias is selected to define a frequency range in which crosstalk between the first and second amplifier channels 104A, 104B is reduced. In other words, the number of vias is optimized to tune the frequency range in which crosstalk between the first and second amplifier channels 104A, 104B is reduced. For example, the via 110A, the via 110B, and subsequent vias are optimized to tune a frequency range in which crosstalk between the first amplifier channel 104A and the second amplifier channel 104B is reduced.

According to one embodiment, the distance between adjacent vias is selected to tune a frequency range in which crosstalk between the first amplifier channel 104A and the second amplifier channel 104B is reduced. In one implementation, the distance between adjacent vias (e.g., the distance between via 110A and via 110B) is referred to as L _VIA. In addition, the distance between adjacent vias is optimized to tune the frequency range in which crosstalk between the first and second amplifier channels 104A, 104B is reduced. In one example, the distance between adjacent vias (e.g., the distance between via 110A and via 110B) is increased to tune the frequency range in which crosstalk between the first amplifier channel 104A and the second amplifier channel 104B is reduced. Similarly, the distance between other adjacent vias (e.g., the distance between the via 110B and a subsequent via) may be reduced to tune the frequency range in which crosstalk between the first amplifier channel 104A and the second amplifier channel 104B is reduced without limiting the scope of the present invention.

The driver amplifier 102 for an optical transmitter includes a first amplifier channel 104A and a second amplifier channel 104B, and each amplifier channel is configured to amplify a respective RF channel signal that further maximizes the available data rate of the optical transmitter. In addition, placement of the shunt capacitor 108 between the common bias line 106 and the ground node through one or more vias 110A-110N reduces inter-channel crosstalk of the driver amplifier 102. In other words, the shunt capacitor 108 facilitates directly reducing inter-channel crosstalk within the driver amplifier 102 without affecting the source data rate and power consumption, bandwidth, gain, output, input return loss, linearity, and design complexity of the optical transmitter. For example, the shunt capacitor 108 reduces crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. Thus, the driver amplifier 102 increases the available data rate of the optical transmitter.

Fig. 1B is a diagram of a driver amplifier provided by another embodiment of the present invention. FIG. 1B is described in conjunction with the elements of FIG. 1A. Referring to fig. 1B, a diagram 100B of a driver amplifier 102 is shown, the driver amplifier 102 including a resistor 114, a first amplifier channel 104A, a second amplifier channel 104B, a common bias line 106, a shunt capacitor 108, and one or more vias 110A-110N.

According to one embodiment, the driver amplifier 102 includes a resistor 114, the resistor 114 being disposed between the shunt capacitor 108 and the common bias line 106. A resistor 114 is disposed between the shunt capacitor 108 and the common bias line 106, the common bias line 106 spanning the first amplifier channel 104A and the second amplifier channel 104B. The resistor 114 added in series to the shunt capacitor 108 is advantageous in reducing high Q resonance.

In one implementation, the length and width of the resistor 114 are selected to tune a frequency range in which crosstalk between the first and second amplifier channels 104A, 104B is reduced. As shown in fig. 1B, the length and width of the resistor 114 are optimized to tune the frequency range in which cross-talk between the first and second amplifier channels 104A, 104B is reduced. In one example, the length of the resistor 114 is increased without changing the width of the resistor 114 to tune the frequency range in which crosstalk between the first and second amplifier channels 104A, 104B is reduced. Similarly, the length of the resistor 114 may be reduced without changing the width of the resistor 114 to tune the frequency range in which crosstalk between the first and second amplifier channels 104A, 104B is reduced. In another example, the width of the resistor 114 is increased without changing the length of the resistor 114 to tune a frequency range in which crosstalk between the first and second amplifier channels 104A, 104B is reduced. Similarly, the width of the resistor 114 may be reduced without changing the length of the resistor 114 to tune the frequency range in which crosstalk between the first and second amplifier channels 104A, 104B is reduced. In yet another example, the length and width of the resistor 114 are increased to tune a frequency range in which crosstalk between the first and second amplifier channels 104A, 104B is reduced. Similarly, the length of the resistor 114 and the width of the resistor 114 may be reduced to tune the frequency range in which cross-talk between the first and second amplifier channels 104A, 104B is reduced.

Fig. 1C and 1D are different illustrations depicting a driver amplifier including a first amplifier channel and a second amplifier channel provided by one embodiment of the invention. Fig. 1C and 1D are described in connection with the elements of fig. 1A and 1B. Referring to fig. 1C, a diagram 100C depicting a first amplifier channel 104A and a second amplifier channel 104B connected by a common bias line 106 is shown. The first amplifier channel 104A has a Direct Current (DC) bias point (e.g., shown as a near circular point) that is connected to a Direct Current (DC) bias point (e.g., shown as a near circular point) of the second amplifier channel 104B by a common bias line 106. Also shown are a coupling signal (e.g., shown by an up arrow) associated with the DC bias point of the first amplifier channel 104A and a transmit signal (e.g., shown by a down arrow) associated with the DC bias point of the second amplifier channel 104B. The first amplifier channel 104A and the second amplifier channel 104B are used to amplify corresponding Radio Frequency (RF) channel signals. Referring to fig. 1D, a diagram 100D depicting a ground node 116, a first amplifier channel 104A, and a second amplifier channel 104B is shown. The ground node 116 may also be referred to as a ground plane for connecting the shunt capacitor 108 (of fig. 1A) between the common bias line 106 and the ground node 116 itself through one or more vias 110A-110N. In one example, the first and second amplifier channels 104A, 104B are provided with a dielectric substrate that reaches the ground node 116 (or ground plane). In addition, the shunt capacitor 108 connected between the common bias line 106 and the ground node 116 reduces inter-channel crosstalk.

Fig. 2 is a block diagram of a light emitter provided by one embodiment of the present invention. Fig. 2 is described in conjunction with the elements of fig. 1A, 1B, 1C, and 1D. Referring to fig. 2, a block diagram 200 of an optical transmitter 202 including a digital source 204, an electro-optic modulator 206, and a drive amplifier 102 is shown. The digital source 204 also includes a first source channel 208A and a second source channel 208B. In addition, the electro-optic modulator 206 also includes a first modulator channel 210A and a second modulator channel 210B. Also shown is an optical channel signal 212 transmitted to a receiver 214.

The optical transmitter 202 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to transmit signals from a source to a destination, such as to the receiver 214. The optical transmitter 202 is used for optical communication.

The digital source 204 includes a first source channel 208A and a second source channel 208B. The first source channel 208A and the second source channel 208B are used to generate respective RF channel signals that are further transmitted to the driver amplifier 102.

The electro-optic modulator 206 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to convert an input (e.g., electrical) signal to an optical signal that may be further transmitted via an optical channel signal 212 to a receiver 214.

A first modulator channel 210A and a second modulator channel 210B are included in the electro-optic modulator 206. In one example, each of the first modulator channel 210A and the second modulator channel 210B is used to convert a respective channel signal to an optical channel signal. For example, the first modulator channel 210A is used to convert a channel signal into an optical channel signal 212. Similarly, the second modulator channel 210B is also used to convert the channel signal into an optical channel signal 212. The receiver 214 may comprise suitable logic, circuitry, interfaces, and/or code that may be operable to receive the optical channel signal 212.

An optical transmitter 202 for optical communication is provided. The light emitter 202 includes a digital source 204, the digital source 204 further including a first source channel 208A and a second source channel 208B. Each source channel is used to generate a channel signal. The optical transmitter 202 further includes a driver amplifier 102 (of fig. 1A or 1B). The driver amplifier 102 increases the power of the channel signal received from the digital source 204. The optical transmitter 202 also includes an electro-optic modulator 206. The electro-optic modulator 206 includes a first modulator channel 210A and a second modulator channel 210B. Each modulator channel is used to convert a corresponding channel signal to an optical channel signal 212. For example, the first modulator channel 210A converts the corresponding channel signal from the first source channel 208A into an optical channel signal 212. Similarly, the second modulator channel 210B converts the corresponding channel signal from the second source channel 208B into an optical channel signal 212. In one example, the optical channel signal 212 is received by a receiver 214.

An optical transmitter 202 for optical communication includes a digital source 204, a driver amplifier 102, and an electro-optic modulator 206. The driver amplifier 102 of the optical transmitter 202 advantageously reduces high frequency inter-channel crosstalk by increasing the data rate capability of the optical transmitter 202 while reducing power consumption.

Modifications may be made to the embodiments of the invention described above without departing from the scope of the invention, which is defined in the appended claims. Expressions such as "comprising," "combining," "having," "being," and the like, which are used to describe and claim the present invention, are intended to be interpreted in a non-exclusive manner, i.e., such that items, components, or elements that are not explicitly described are also present. Reference to the singular is also to be construed to relate to the plural. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any embodiment described as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments, or as an exclusion of any combination of features from other embodiments. The word "optionally" as used herein means "provided in some embodiments and not provided in other embodiments. It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable combination or as in any other described embodiment of the invention.

Claims

1. A driver amplifier (102) for an optical transmitter (202), comprising:

A first amplifier channel (104A) and a second amplifier channel (104B), each for amplifying a respective Radio Frequency (RF) channel signal, the first amplifier channel (104A) and the second amplifier channel (104B) each having a Direct Current (DC) bias point;

-a common bias line (106) interconnecting the DC bias point of the first amplifier channel (104A) with the DC bias point of the second amplifier channel (104B);

A ground node (116);

A shunt capacitor (108) connected between the common bias line (106) and the ground node (116) through one or more vias (110A-110N),

Wherein the first amplifier channel (104A) and the second amplifier channel (104B) are arranged symmetrically to each other on both sides of a symmetry plane, and the parallel capacitor (108) is placed on the symmetry plane.

2. The driver amplifier (102) of claim 1, wherein the shunt capacitor (108) is connected at a midpoint of the common bias line (106) between the first amplifier channel (104A) and the second amplifier channel (104B).

3. The driver amplifier (102) of claim 1 or 2, wherein one or more of the vias (110A-110N) are included within the area of the shunt capacitor (108).

4. A driver amplifier (102) as claimed in claim 3, characterized in that the number of vias in the region of the shunt capacitor (108) is selected to tune a frequency range in which crosstalk between the first amplifier channel (104A) and the second amplifier channel (104B) is reduced.

5. The driver amplifier (102) of any of the preceding claims, wherein one or more of the vias (110A-110N) are outside the area of the shunt capacitor (108).

6. The driver amplifier (102) of any of the preceding claims, wherein each of the amplifier channels is a wideband amplifier.

7. The driver amplifier (102) of any of the preceding claims, wherein the number of vias is selected to define a frequency range in which crosstalk between the first amplifier channel (104A) and the second amplifier channel (104B) is reduced.

8. The driver amplifier (102) of any of the preceding claims, wherein the distance between adjacent vias is selected to tune a frequency range in which crosstalk between the first amplifier channel (104A) and the second amplifier channel (104B) is reduced.

9. The driver amplifier (102) of any of the above claims, wherein the length and width of the shunt capacitor (108) are selected to tune a frequency range in which crosstalk between the first amplifier channel (104A) and the second amplifier channel (104B) is reduced.

10. The driver amplifier (102) of any of the preceding claims, further comprising a resistor (114) arranged between the parallel capacitor and the common bias line.

11. The driver amplifier (102) of claim 10, wherein the length and width of the resistor (114) are selected to tune a frequency range in which crosstalk between the first amplifier channel (104A) and the second amplifier channel (104B) is reduced.

12. An optical transmitter (202) for optical communication, comprising:

a digital source (204) comprising a first source channel (208A) and a second source channel (208B), each source channel for generating a respective RF channel signal;

The driver amplifier (102) of any one of the preceding claims;

an electro-optic modulator (206) includes a first modulator channel (210A) and a second modulator channel (210B), each modulator channel for converting a respective RF channel signal to an optical channel signal (212).