WO2023165699A1

WO2023165699A1 - Driver amplifier for optical transmitter and optical transmitter for optical communication

Info

Publication number: WO2023165699A1
Application number: PCT/EP2022/055434
Authority: WO
Inventors: Luca PIAZZON; Antonio Musio
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2022-03-03
Filing date: 2022-03-03
Publication date: 2023-09-07

Abstract

A driver amplifier for an optical transmitter includes a first and a second amplifier channel, each configured to amplify a respective radio frequency channel signal. The first and the second amplifier channel each include a direct current (DC) bias point. The driver amplifier further includes a common bias line interconnecting the DC bias points of the first and the second amplifier channels. The driver amplifier further includes a ground node and a shunt capacitor that is connected between the common bias line and the ground node through one or more via-holes. The first and the second amplifier channels are arranged symmetrically to each other on two sides of a symmetry plane and the shunt capacitor is placed on the symmetry plane. The shunt capacitor is beneficial to reduce the channel-to-channel crosstalk directly inside the driver amplifier without increasing the data rate and the power consumption of the optical transmitter.

Description

DRIVER AMPLIFIER FOR OPTICAL TRANSMITTER AND OPTICAL TRANSMITTER FOR OPTICAL COMMUNICATION

TECHNICAL FIELD

The present disclosure relates generally to the field of ultra- wideband multi-channel amplifiers for optical communication and, more specifically, to a driver amplifier for an optical transmitter and the optical transmitter for optical communication.

BACKGROUND

Generally, optical communication uses light as a medium to carry signals from a source end to a destination end via an optical fiber. Further, optical transmitters are used for high-speed optical communications, which are implemented by cascading a digital source, a driver amplifier, and an electro-optical modulator. The conventional driver amplifier is used to increase a power level of a digital signal (e.g., an electrical signal), which is generated by the digital source to provide an appropriate power supply to the electro-optical modulator. Further, the electro-optical modulator is configured to transduce (i.e., convert) the electrical signal to an optical signal which is transferred via the optical fiber. Each component (i.e., the digital source, the driver amplifier, and the electro-optical modulator) integrates multiple channels to increase the data rate of the optical transmitter. Moreover, the use of multiple channels increases channel-to-channel crosstalk. The channel-to-channel crosstalk behaves like an added noise that reduces the overall quality of an output signal, which further limits the data rate of the optical transmitter.

Typically, the conventional optical transmitters propose to cancel, or reduce, the channel-to- channel crosstalk by implementing a digital cancellation function in a high-speed digital source. Moreover, an inverse crosstalk signal is added to an input signal of each channel to cancel the channel-to-channel crosstalk coming from other channels. However, the data rate of the optical transmitter is still not desirable, and the power consumption of the conventional optical transmitter is also increased as the crosstalk digital cancellation function requires additional digital blocks for its implementation. Thus, there exists a technical problem to how to reduce high-frequency channel-to-channel crosstalk directly on the driver amplifier to push the maximum data-rate capability of the optical transmitter while minimizing the power consumption. Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks associated with conventional optical transmitters.

SUMMARY

The present disclosure provides a driver amplifier for an optical transmitter and the optical transmitter for optical communication. The present disclosure provides a solution to the existing problem of how to reduce high-frequency channel-to-channel crosstalk directly on the driver amplifier to push the maximum data-rate capability of the optical transmitter while minimizing the power consumption. An objective of the present disclosure is to provide a solution that overcomes at least partially the problems encountered in the prior art and provides an improved driver amplifier for the optical transmitter and an improved optical transmitter for optical communication with reduced high-frequency channel-to-channel crosstalk for optical communication.

One or more objectives of the present disclosure are achieved by the solutions provided in the enclosed independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims.

In one aspect, the present disclosure provides a driver amplifier for an optical transmitter comprising a first amplifier channel and a second amplifier channel, each configured to amplify a respective radio frequency (RF) channel signal, the first amplifier channel and the second amplifier channel 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 and 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 via-holes. The first amplifier channel and the second amplifier channel are arranged symmetrically to each other on two sides of a symmetry plane, and the shunt capacitor is placed on the symmetry plane.

The symmetry plane is a plane of symmetry of the first and the second amplifier channel. That is, reflecting the first amplifier channel geometrically by the symmetry plane transforms any part of the first amplifier channel geometrically into a part of the second amplifier channel, and vice versa. The driver amplifier as a whole is not necessarily symmetric with respect to the symmetry plane of the first and the second amplifier. The driver amplifier for the optical transmitter includes the first amplifier channel and the second amplifier channel to amplify the respective radio frequency (RF) channel signal. The first amplifier channel and the second amplifier channel each have a direct current (DC) bias point that further maximizes the available data rate of the optical transmitter. Moreover, the arrangement of the shunt capacitor between the common bias line and the ground node through one or more via-holes reduces the channel-to-channel crosstalk directly inside the driver amplifier without increasing the data rate and the power consumption of the optical transmitter.

In an implementation form, the shunt capacitor is connected at a midpoint of the common bias line between the first amplifier channel and the second amplifier channel.

The shunt capacitor connected at the midpoint of the common bias line between the first amplifier channel and the second amplifier channel does not affect the performance of the driver amplifier, such as power consumption, bandwidth, gain, output, and input return loss, linearity, design complexity, and biasing. Moreover, the shunt capacitor provides a maximum data rate with reduced channel-to-channel crosstalk.

In a further implementation form, one or more of the via-holes are included within an area of the shunt capacitor.

By virtue of using the one or more via-holes within the area of the shunt capacitor, there exists a reduced high-frequency channel-to-channel crosstalk.

In a further implementation form, one or more of the via-holes are outside an area of the shunt capacitor.

In this implementation, the number of via-holes provides the selection of frequency range that further reduces the channel-to-channel crosstalk.

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

In this implementation, the wideband amplifier delivers the required biasing voltage to each amplifier channel.

In a further implementation form, the driver amplifier further includes a resistor arranged between each shunt capacitor and the common bias line. In this implementation, the addition of the resistor arranged between each shunt capacitor reduces the high-quality resonance.

In another aspect, the present disclosure provides an optical transmitter for optical communications comprising a digital source including a first source channel and a second source channel, each configured to generate a respective radio frequency (RF) channel signal. The optical transmitter further includes a driver amplifier and an electro-optical modulator including a first modulator channel and a second modulator channel, each configured to transduce a respective radio frequency (RF) channel signal into an optical channel signal.

The optical transmitter for optical communication achieves all the advantages and technical effects of the driver amplifier of the present disclosure.

It is to be appreciated that all the aforementioned implementation forms can be combined. It has to be noted that all devices, elements, circuitry, units, and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity that performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof. It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.

Additional aspects, advantages, features, and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative implementations construed in conjunction with the appended claims that follow. BRIEF DESCRIPTION OF THE DRAWINGS

The summary above, 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 present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.

Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:

FIG. 1A is an illustration of a driver amplifier, in accordance with an embodiment of the present disclosure;

FIG. IB is an illustration of a driver amplifier, in accordance with another embodiment of the present disclosure;

FIG. 1C and FIG. ID are different illustrations of a driver amplifier that include a first amplifier channel and a second amplifier channel, in accordance with different embodiments of the present disclosure; and

FIG. 2 is a block diagram of an optical transmitter, in accordance with an embodiment of the present disclosure.

In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the nonunderlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.

DETAILED DESCRIPTION OF EMBODIMENTS

The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible. FIG. 1A is an illustration that depicts a driver amplifier, in accordance with an embodiment of the present disclosure. With reference to FIG.1A, there is shown an illustration 100A of a driver amplifier 102 that includes a first amplifier channel 104A, a second amplifier channel 104B, a common bias line 106, a shunt capacitor 108, one or more via-holes 110A to 110N, and a bias pad 112. It is to be understood that in FIG. 1 A, a rounded rectangle with a dashed line is used to depict an area of the shunt capacitor 108. Similarly, a rounded rectangle with a plane line is used to depict the area that includes the one or more via-holes 110A to 110N.

The driver amplifier 102 for an optical transmitter includes the first amplifier channel 104A and the second amplifier channel 104B, and each is configured to amplify and increase the power level of the respective radio frequency (RF) channel signals for optical communication.

The first amplifier channel 104A and the second amplifier channel 104B are configured to amplify the respective radio frequency (RF) channel signal. For example, the first amplifier channel 104A of the driver amplifier 102 is configured to amplify the radio frequency (RF) channel signal of an input signal (INI) and produce an amplified output (OUT1). Similarly, the second amplifier channel 104B of the driver amplifier 102 is configured to increase and amplify the radio frequency (RF) channel signal of another input signal (IN2) and produce an amplified output (OUT2). The first amplifier channel 104A and the second amplifier channel 104B have direct current (DC) bias points. In an implementation, the driver amplifier 102 includes more than two amplifier channels. In an 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 configured to interconnect the DC bias point of the first amplifier channel 104A and the DC bias point of the second amplifier channel 104B. In an example, the common bias line 106 is used to deliver the required biasing voltage to the first amplifier channel 104A and the second amplifier channel 104B (or to each amplification stage).

The shunt capacitor 108 is connected between the common bias line 106 and the ground node through one or more via-holes 110A to 110N. Each via-hole from the one or more via-holes 110A to 110N may also be referred to as a trench, an opening, or a hole. In an example, the one or more via-holes 110A to 110N are formed via standard lithography or etching techniques.

There is provided the driver amplifier 102 for the optical transmitter. The driver amplifier 102 includes the first amplifier channel 104A and the second amplifier channel 104B. Each amplifier channel is configured to amplify the power level of the respective radio frequency (RF) channel signal. In an example, the first amplifier channel 104A amplifies the respective radio frequency (RF) channel signal (or power level), such as of the input signal (IN 1), and also produces an amplified output (OUT1). Similarly, the second amplifier channel 104B amplifies the respective RF channel signal (or power level), such as of the input signal (IN2), and produces an amplified output (OUT2). In an example, the driver amplifier 102 includes more than two amplifier channels such as three amplifier channels or four amplifier channels. The first amplifier channel 104A and the second amplifier channel 104B have the direct current (DC) bias point. The driver amplifier 102 further includes the common bias line 106 that is arranged to interconnect the DC bias point of the first amplifier channel 104A and the DC bias point of the second amplifier channel 104B. In an example, the common bias line 106 delivers the required biasing voltage to the first amplifier channel 104A, and also to the second amplifier channel 104B. The first amplifier channel 104A and the second amplifier channel 104B are arranged symmetrically to each other on two sides of a symmetry plane A- A and the shunt 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. Moreover, the second amplifier channel 104B is arranged on another side of the symmetry plane A-A, such as arranged symmetrically to the first amplifier channel 104A, as shown in described the FIG. 1A and FIG. IB. In accordance with an embodiment, each of the amplifier channels is a wideband amplifier. The wideband amplifier corresponds to an amplifier with a precise amplification factor over a wide frequency range. The wideband amplifier is beneficial to boost the channel signal and also to provide amplified signals.

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

The shunt capacitor 108 is beneficial to reduce channel-to-channel crosstalk directly inside 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. As a result, the driver amplifier 102 allows to improve (or maximize) the available data rate of the optical transmitter.

In accordance with an embodiment, 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. Beneficially as compared to conventional amplifiers, the arrangement of the shunt capacitor 108 between the first amplifier channel 104A and the second amplifier channel 104B reduces the high-frequency channel-to-channel crosstalk in the driver amplifier 102.

In an implementation, a length and a width of the shunt capacitor 108 are selected to tune the frequency range in which to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. In an example, the length of the shunt capacitor 108 is referred to as LCAP, and the width of the shunt capacitor 108 is referred to as WCAP, as shown in FIG. 1A. Moreover, the length, as well as the width of the shunt capacitor 108, are optimized to tune the frequency range to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. In an example, the length of the shunt capacitor 108 is increased without changing the width of the shunt capacitor 108 to tune the frequency range and to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. Similarly, the length of the shunt capacitor 108 can be decreased without changing the width of the shunt capacitor 108 to tune the frequency range and to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. In another example, the width of the shunt capacitor 108 is increased without changing the length of the shunt capacitor 108 to tune the frequency range and to reduce the crosstalk between the adjacent amplifier channels. Similarly, the width of the shunt capacitor 108 can be decreased without changing the length of the shunt capacitor 108 to tune the frequency range and to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. In yet another example, the length and the width of the shunt capacitor 108 are increased to tune the frequency range in which to reduce the crosstalk between the adjacent amplifier channels. Similarly, the length of the shunt capacitor 108 and the width of the shunt capacitor 108 can be decreased simultaneously to tune the frequency range in which to reduce crosstalk between the first amplifier channel 104A and the second amplifier channel 104B.

In accordance with an embodiment, one or more of the via-holes 110A to 110N are included within the area of the shunt capacitor 108. In an implementation, the shunt capacitor 108 is arranged between the first amplifier channel 104A and the second amplifier channel 104B. Further, the one or more of the via-holes 110A to 110N are included within the area of the shunt capacitor 108. For example, the shunt capacitor 108 arranged between the first amplifier channel 104A and the second amplifier channel 104B includes a via-hole 110A and a via-hole HOB. In an implementation, the number of via-holes within the area of the shunt capacitor 108 is selected to tune the frequency range in which to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. In an example, the number of via-holes within the area of the shunt capacitor 108 is more than zero, such as the via-hole 110A and the via-hole HOB are included within the area of the shunt capacitor 108. In another example, the number of via-holes within the area of the shunt capacitor 108 is zero. Beneficially, the number of via-holes within the area of the shunt capacitor 108 enables the shunt capacitor 108 to tune the frequency range and to reduce the crosstalk between the first amplifier channellO4A and the second amplifier channel 104B.

In accordance with an embodiment, the one or more of the via-holes 110A to 110N are arranged outside an area of the shunt capacitor 108. In an example, the shunt capacitor 108 is arranged between the common bias line 106 and the ground node through the one or more via-holes 110A to 110N. Moreover, the one or more of the via-holes 110A to 110N are included outside the area of the shunt capacitor 108. For example, the shunt capacitor 108 is arranged between the common bias line 106 and the ground node, and a via-hole 110N is arranged outside the area of the shunt capacitor 108, as shown in FIG. 1A.

In accordance with an embodiment, the number of via-holes is selected to define the frequency range to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. In other words, the number of via-holes is optimized to tune the frequency range and to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. For example, the via-hole 110A, the via-hole HOB, and the subsequent via holes are optimized to tune the frequency range and also to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B.

In accordance with an embodiment, a distance between adjacent via-holes is selected to tune the frequency range to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. In an implementation, the distance between adjacent viaholes such as the distance between the via-hole 110A and the via-hole HOB is referred to as LVIA. In addition, the distance between adjacent via-holes is optimized to tune the frequency range in which to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. In an example, the distance between the adjacent via-holes, such as between the via-hole 110A and the via-hole HOB, is increased to tune the frequency range in which to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. Similarly, the distance between another adjacent via-holes, such as between the via-hole HOB and a subsequent via-hole can be decreased to tune the frequency range to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B without limiting the scope of the present disclosure.

The driver amplifier 102 for the optical transmitter includes the first amplifier channel 104A and the second amplifier channel 104B, and each is configured to amplify the respective RF channel signal that further maximizes the available data rate of the optical transmitter. Moreover, the arrangement of the shunt capacitor 108 between the common bias line 106 and the ground node through the one or more via-holes 110A to 110N reduces the channel- to-channel crosstalk of the driver amplifier 102. In other words, the shunt capacitor 108 is beneficial to reduce channel-to-channel crosstalk directly inside 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. As a result, the driver amplifier 102 improves the available data rate of the optical transmitter. FIG. IB is an illustration of a driver amplifier, in accordance with another embodiment of the present disclosure. FIG. IB is described in conjunction with elements from FIG. 1A. With reference to FIG. IB, there is shown an illustration 100B of the driver amplifier 102 that includes a resistor 114, the first amplifier channel 104A, the second amplifier channel 104B, the common bias line 106, the shunt capacitor 108, and the one or more via-holes 110A to 110N.

In accordance with an embodiment, the driver amplifier 102 includes the resistor 114 that is arranged between the shunt capacitor 108 and the common bias line 106. The resistor 114 is arranged between the shunt capacitor 108 and the common bias line 106 that crosses the first amplifier channel 104A and the second amplifier channel 104B. The resistor 114 added in series to the shunt capacitor 108 is beneficial to reduce the high Q resonance.

In an implementation, a length and a width of the resistor 114 are selected to tune the frequency range in which to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. The length and width of the resistor 114, as shown in FIG. IB, are optimized to tune the frequency range and also to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. In an example, the length of the resistor 114 is increased without changing the width of the resistor 114 to tune the frequency range and to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. Similarly, the length of the resistor 114 can be decreased without changing the width of the resistor 114 to tune the frequency range and to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. In another example, the width of the resistor 114 is increased without changing the length of the resistor 114 to tune the frequency range to reduce crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. Similarly, the width of the resistor 114 can be decreased without changing the length of the resistor 114 to tune the frequency range to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. In yet another example, the length and the width of the resistor 114 are increased to tune the frequency range to reduce the crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. Similarly, the length of the resistor 114 and the width of the resistor 114 can be decreased to tune the frequency range to reduce crosstalk between the first amplifier channel 104A and the second amplifier channel 104B. FIG. 1C and FIG. ID are different illustrations that depicts driver amplifiers that include a first amplifier channel and a second amplifier channel, in accordance with an embodiment of the present disclosure. FIGs. 1C and ID are described in conjunction with elements from FIGs. 1A and IB. With reference to FIG. 1C, there is shown an illustration 100C that depicts the first amplifier channel 104A and the second amplifier channel 104B are connected through the common bias line 106. The first amplifier channel 104A has a direct current (DC) bias point (e.g., shown near-circular point) that is connected to a direct current (DC) bias point (e.g., shown near-circular point) of the second amplifier channel 104B through the common bias line 106. There is further shown a coupled signal (e.g., shown by upside arrows) associated with the DC bias point of the first amplifier channel 104A, and a delivered signal (e.g., shown by downside arrows) associated with the DC bias point of the second amplifier channel 104B. The first amplifier channel 104A and the second amplifier channel 104B are configured to amplify a respective radio frequency (RF) channel signal. With reference to FIG. ID, there is shown an illustration 100D that depicts a ground node 116, the first amplifier channel 104A, and the second amplifier channel 104B. The ground node 116 may also be referred to as a ground plane, which is used to connect the shunt capacitor 108 (of FIG. 1 A) between the common bias line 106 and the ground node 116 itself through the one or more via-holes 110A to 110N. In an example, the first amplifier channel 104A and the second amplifier channel 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 the channel to channel crosstalk.

FIG. 2 is a block diagram of an optical transmitter, in accordance with an embodiment of the present disclosure. FIG. 2 is described in conjunction with elements from FIGs. 1A, IB, 1C, and ID. With reference to FIG. 2, there is shown a block diagram 200 of an optical transmitter 202 that includes a digital source 204, an electro-optical modulator 206, and the driver amplifier 102. The digital source 204 further includes a first source channel 208A and a second source channel 208B. Moreover, the electro-optical modulator 206 further includes a first modulator channel 210A and a second modulator channel 210B. There is further shown an optical channel signal 212 that is transmitted to a receiver 214. The optical transmitter 202 includes suitable logic, circuitry, interfaces, and/or code that is configured to transmit a signal from a source end to destination end, such as to the receiver 214. The optical transmitter 202 is used for optical communication.

The digital source 204 includes the first source channel 208A and the second source channel 208B. The first source channel 208A and the second source channel 208B are configured to generate the respective RF channel signal that is further transferred to the driver amplifier 102.

The electro-optical modulator 206 includes suitable logic, circuitry, interfaces, and/or code that is configured to transduce an input (e.g., electrical) signal to an optical signal, which is further transferred to the receiver 214, and through the optical channel signal 212.

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

There is provided the optical transmitter 202 that is used for optical communications. The optical transmitter 202 includes the digital source 204, which further includes the first source channel 208A and the second source channel 208B. Each source channel is configured to generate the channel signal. The optical transmitter 202 further includes the driver amplifier 102 (of FIG. 1A or IB). The driver amplifier 102 increases the power of the channel signals received from the digital source 204. The optical transmitter 202 further includes the electro- optical modulator 206. The electro-optical modulator 206 includes the first modulator channel 210A and the second modulator channel 210B. Each modulator channel is configured to transduce the respective channel signal into the optical channel signal 212. For example, the first modulator channel 210A transduces the respective channel signal from the first source channel 208A into the optical channel signal 212. Similarly, the second modulator channel 210B transduces the respective channel signal from the second source channel 208B into the optical channel signal 212. In an example, the optical channel signal 212 is received by the receiver 214.

The optical transmitter 202 for optical communication includes the digital source 204, the driver amplifier 102, and the electro-optical modulator 206. The driver amplifier 102 of the optical transmitter 202 is beneficial to reduce high-frequency channel-to-channel crosstalk with the improved data-rate capability of the optical transmitter 202 while reducing power consumption.

Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "have", "is" used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be 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 to exclude the incorporation of features from other embodiments. The word "optionally" is used herein to mean "is provided in some embodiments and not provided in other embodiments". It is appreciated that certain features of the present disclosure, 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 suitable in any other described embodiment of the disclosure.

Claims

1. A driver amplifier (102) for an optical transmitter (202), comprising: a first amplifier channel (104 A) and a second amplifier channel (104B), each configured to amplify 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 (104 A) and the DC bias point of the second amplifier channel (104B); a ground node (116); and a shunt capacitor (108) connected between the common bias line (106) and the ground node (116) through one or more via-holes (110A to 110N), wherein the first amplifier channel (104 A) and the second amplifier channel (104B) are arranged symmetrically to each other on two sides of a symmetry plane and the shunt 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 (104 A) and second amplifier channel (104B).

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

4. The driver amplifier (102) of claim 3, wherein a number of via-holes within the area of the shunt capacitor (108) is selected to tune a frequency range in which to reduce crosstalk between the first amplifier channel (104 A) and the second amplifier channel (104B).

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

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

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

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

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

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

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

12. An optical transmitter (202) for optical communications comprising: a digital source (204) including a first source channel (208A) and a second source channel (208B) each configured to generate a respective RF channel signal; the driver amplifier (102) of any preceding claim; and an electro-optical modulator (206) including a first modulator channel (210A) and a second modulator channel (210B) each configured to transduce a respective RF channel signal into an optical channel signal (212).