DRIVER STAGE CURRENT DENSITY ENHANCEMENT

A transistor device can include a drain contact operably connected to a drain finger and a source contact operably connected to a source finger. The transistor device can further include diffusion area connected to the drain finger and the source finger to provide current to the drain finger and the source finger. The drain finger can have a length extending along an axis and different drain finger widths along the drain finger length such that current density is equal at each point along the drain finger length. The source finger can have a length extending along the axis and source finger widths along the source finger length such that current density is equal at each point along the source finger length.

TECHNICAL FIELD

Aspects pertain to electronic devices. In particular, aspects relate to transistor architecture for transistors used in electronic devices.

BACKGROUND

Power amplifiers and driver stages are used in a variety of applications. The choice and design of electrical components can affect key performance indicators of power amplifiers and associated circuits or driver stages of communication devices or other devices. For example, device packages for a radio frequency (RF) power amplifier can include a transistor die (e.g., metal-oxide semiconductor field-effect transistor (MOSFET)). Reducing or minimizing parasitic capacitance and coupling within the MOSFET may improve key performance indicators for the driver stage and for devices including the respective driver stage.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustrate specific aspects to enable those skilled in the art to practice them. Other aspects may incorporate structural, logical, electrical, process, and other changes. Portions and features of some aspects may be included in, or substituted for, those of other aspects. Aspects set forth in the claims encompass all available equivalents of those claims.

Radio communication apparatuses may include power amplifier (PA) devices. Power amplifier resistance and output capacitance are two of the main parameters defining key performance indicators (KPIs) of the PA and circuits including the PA. Some high frequency PA circuit devices can include Metal Oxide Semiconductor Field-Effect-Transistors (MOSFETs) and MOSFET layout decisions can be made to adjust parameters that affect KPIs. For example, to reduce parasitic resistance, a metal overlay can be provided over the contacts of the MOSFET and the number of electrical connections (e.g., vias or through-vias) can be increased or maximized. However, this can result in additional parasitic capacitance. On the other hand, steps to minimize coupling to reduce parasitic capacitance can increase the layout area of the MOSFET, causing packaging concerns and size concerns.

Systems, apparatuses and methods according to some aspects of the disclosure address these and other concerns by providing a layout solution that maintains adequate current density throughout the MOSFET without increasing size or layout area of the MOSFET and without additional parasitic “ON” resistance or parasitic capacitance. Proposed solutions enable efficient current distribution through the MOSFET and increase driver stage and output stage efficiency.

FIG.1illustrates front end module (FEM) circuitry100that can include MOSFETs or other transistor circuitry in accordance with some aspects. In some aspects, the FEM circuitry100may include a TX/RX switch102to switch between transmit mode and receive mode operation. The FEM circuitry100may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry100may include a low-noise amplifier (LNA)206to amplify received RF signals203and provide the amplified received RF signals207as an output. The transmit signal path of the circuitry100may include a power amplifier (PA) to amplify input RF signals209, and one or more filters112, such as band-pass filters (BPFs), low-pass filters (LPFs) or other types of filters, to generate RF signals215for subsequent transmission (e.g., by one or more of antennas (not shown inFIG.1).

One or more of the PAs described above can include transistor circuitry and overall parasitics should be kept as low as possible while maintaining current density throughout the transistor. Transistors according to example embodiments can maintain current density using routing and configuration as shown inFIG.2. The routing and tapering configuration shown inFIG.2can maintain a constant current density along FET fingers204,208(FIG.2) without increasing the coupling between FET fingers204,208. This routing will have a tapered shape. Increased metal width on one finger side and decreased on the other.

FIG.2illustrates a transistor device200in accordance with some aspects. The transistor device200can include a drain contact202electrically connected to a drain finger204. The transistor device200can include a source contact206electrically connected to a source finger208. The transistor device200can include a diffusion area210between the drain finger204and the source finger208to provide current212between the drain finger204and the source finger208.

The drain finger204can have a drain finger length214extending along a Y axis and a plurality of different drain finger widths216,218,220,222along the drain finger length214such that current density is equal or substantially equal (within a percentage range of 0.1-5%) at each point along the drain finger length214. The source finger208can have a source finger length224extending along the Y axis and a plurality of different source finger widths226,228,230,232along the source finger length224such that current density is equal at each point along the source finger length224.

The drain finger204can include a first drain finger width216at a point along the drain finger length214nearest the drain contact202and at least one other drain finger width218,220or222smaller than the first drain finger width216. The at least one other drain finger width218,220or222can be at a point along the drain finger length214further from the drain contact202than the first drain finger width216.

Similarly, the source finger208can have a first source finger width226at a point along the source finger length228nearest the source contact206and at least one other source finger width228,230,232smaller than the first source finger width226. The other source finger width/s228,230,232can be at one or more point/s along the source finger length224further from the source contact206than the first source finger width226.

While four source finger widths226,228,230,232are shown, there may be more or fewer width/s (e.g., tapering can occur with more or fewer steps or widths along the length of the source finger). Similarly, while four drain finger widths216,218,220,222are shown, there may be more or fewer width/s (e.g., tapering can occur with more or fewer steps or widths along the length of the drain finger).

FIG.3illustrates example proportions and layout of transistor devices in accordance with some aspects. As seen inFIG.3, a distance306between the drain finger208and the source finger204can be constant or near-constant along the drain finger length and the source finger length. An overall width310of the transistor can also be maintained. In examples, a smallest-width taper of the source finger208can have a same width302as a smallest-width taper308of the drain finger204. Similarly, in examples, a largest-width taper of the source finger208can have a same width304as a largest-width taper of the drain finger204. Proportionate widths can extend along lengths of each of the source finger208and drain finger204such that a constant distance306is maintained between the source finger208and the drain finger204. As the widths can be kept relatively constant relative to previous designs, overall area of a transistor device can be kept the same or near-same while maintaining current density without increasing parasitic contributions of the transistor device200(FIG.2).

Referring again toFIG.2, the device200can include a plurality of layers. Electrical connections (e.g., vias)234can be provided between at least two of the plurality of layers and below at least one discrete width segment226,228,230,232of the source finger and at least one discrete width segment216,218,220,232of the drain finger204.

Current within the transistor device200can flow from the drain contact202to the source contact206by flowing from drain metal layers to electrical contacts (e.g., through the electrical connections or vias234). From the electrical contacts234, current flows through the diffusion area210that connects the source contact206and drain contact202(e.g., in silicon or non-metal portions below the electrical connections234). From the diffusion area210, current flows to source electrical connections (or vias)236and from there to metal source metal layers206.

As current propagates through the finger204, the current amplitude decreases along the way because some of the current is provided from the drain finger204to the source finger208through the diffusion area210(e.g., in the X direction from drain contact202to source contact206). Because the width of the metal decreases along the length of the metal finger204, current density remains the same given that current density equals current divided by width, i.e., if metal width is decreased by the same factor as current along the FET finger, current density remains the same. A constant or maintained current density improves the KPIs of power amplifiers as described earlier herein and accordingly the transistor design of example aspects improves the KPIs of power amplifiers used in many modern user devices.

In addition, the electrical contacts234,236do not extend along the entire length of drain finger204and drain finger208, and current is reduced at each metal contact234,236. Current flows (and decreases) at each electrical contact234,236and accordingly width should be reduced at each electrical contact234,236to maintain the same current density.

Increasing metal width on one side of the finger and decreasing it on the other side (by the same value) does not change the distance between metal fingers, meaning that capacitance between FET fingers does not increase.

It will further be appreciated that example transistor device200can be included in other driver stages or other devices in addition to the power amplifiers described herein. Transistors according to aspects are not limited to usage in any particular type of device or apparatus.

Other Systems and Apparatuses

FIG.4illustrates a functional block diagram of a wireless communication device, in accordance with some embodiments. In some embodiments,FIG.4illustrates a functional block diagram of a communication device (STA) that may be suitable for use as an AP STA, a non-AP STA or other user device in accordance with some embodiments. The communication device may also be suitable for use as a handheld device, a mobile device, a cellular telephone, a smartphone, a tablet, a netbook, a wireless terminal, a laptop computer, a wearable computer device, a femtocell, a high data rate (HDR) subscriber device, an access point, an access terminal, or other personal communication system (PCS) device.

The communication device may include communications circuitry602and transceiver circuitry610for transmitting and receiving signals to and from other communication devices using one or more antennas601. The communications circuitry602may include circuitry that can operate the physical layer (PHY) communications and/or medium access control (MAC) communications for controlling access to the wireless medium, and/or any other communications layers for transmitting and receiving signals. The communication device may also include processing circuitry606and memory608arranged to perform the operations described herein. In some embodiments, the communications circuitry602and the processing circuitry606may be configured to perform operations detailed in the above figures, diagrams, and flows.

In accordance with some embodiments, the communications circuitry602may be arranged to contend for a wireless medium and configure frames or packets for communicating over the wireless medium. The communications circuitry602may be arranged to transmit and receive signals. The communications circuitry602may also include circuitry for modulation/demodulation, upconversion/downconversion, filtering, amplification, etc. In some embodiments, the processing circuitry606of the communication device may include one or more processors. In other embodiments, two or more antennas601may be coupled to the communications circuitry602arranged for sending and receiving signals. The memory608may store information for configuring the processing circuitry606to perform operations for configuring and transmitting message frames and performing the various operations described herein. The memory608may include any type of memory, including non-transitory memory, for storing information in a form readable by a machine (e.g., a computer). For example, the memory608may include a computer-readable storage device, read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices and other storage devices and media.

In some embodiments, the communication device may be part of a portable wireless communication device, such as a personal digital assistant (PDA), a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone, a smartphone, a wireless headset, a pager, an instant messaging device, a digital camera, an access point, a television, a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), a wearable computer device, or another device that may receive and/or transmit information wirelessly.

In some embodiments, the communication device may include one or more of a keyboard, a display, a non-volatile memory port, multiple antennas, a graphics processor, an application processor, speakers, and other mobile device elements. The display may be an LCD screen including a touch screen.

References to “one aspect”, “an aspect”, “an example aspect,” “some aspects,” “demonstrative aspect”, “various aspects” etc., indicate that the aspect(s) so described may include a particular feature, structure, or characteristic, but not every aspect necessarily includes the particular feature, structure, or characteristic. Further, repeated use of the phrase “in one aspect” does not necessarily refer to the same aspect, although it may.

The term “communicating” as used herein with respect to a communication signal includes transmitting the communication signal and/or receiving the communication signal. For example, a communication unit, which is capable of communicating a communication signal, may include a transmitter to transmit the communication signal to at least one other communication unit, and/or a communication receiver to receive the communication signal from at least one other communication unit. The verb communicating may be used to refer to the action of transmitting and/or the action of receiving. In one example, the phrase “communicating a signal” may refer to the action of transmitting the signal by a first device and may not necessarily include the action of receiving the signal by a second device. In another example, the phrase “communicating a signal” may refer to the action of receiving the signal by a first device and may not necessarily include the action of transmitting the signal by a second device.

As used herein, the term “circuitry” may, for example, refer to, be part of, or include, an Application Specific Integrated Circuit (ASIC), an integrated circuit, an electronic circuit, a processor (shared, dedicated, or group), and/or memory (shared, dedicated, or group), that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some aspects, circuitry may include logic, at least partially operable in hardware. In some aspects, the circuitry may be implemented as part of and/or in the form of a radio virtual machine (RVM), for example, as part of a Radio processor (RP) configured to execute code to configured one or more operations and/or functionalities of one or more radio components.

Additional Notes and Aspects

Example 1 is a transistor device including: a drain contact operably connected to a drain finger; a source contact operably connected to a source finger; a diffusion area connected to the drain finger and the source finger to provide current to the drain finger and the source finger; the drain finger having a drain finger length extending along an axis and a plurality of different drain finger widths along the drain finger length such that current density is equal at each point along the drain finger length; and the source finger having a source finger length extending along the axis and a plurality of different source finger widths along the source finger length such that current density is equal at each point along the source finger length.

In Example 2, the subject matter of Example 1 can optionally include wherein the drain finger has a first drain finger width at a point along the drain finger length nearest the drain contact and at least one other drain finger width smaller than the first drain finger width, the at least one other drain finger width being at a point along the drain finger length further from the drain contact than the first drain finger width.

In Example 3, the subject matter of Example 2 can optionally include wherein the source finger has a first source finger width at a point along the source finger length nearest the source contact and at least one other source finger width smaller than the first source finger width, the at least one other source finger width being at a point along the source finger length further from the source contact than the first source finger width.

In Example 4, the subject matter of Example 2 can optionally include wherein the transistor device comprises a plurality of layers.

In Example 5, the subject matter of Example 4 can optionally include electrical connections between at least two of the plurality of layers, the electrical connections provided below at least one discrete width segment of the source finger and at least one discrete width segment of the drain finger.

In Example 6, the subject matter of any of Examples 1-5 can optionally include wherein a distance between the drain finger and the source finger is constant along the drain finger length and the source finger length.Example 7 is driver stage circuitry comprising: an input terminal and an output terminal; and at least one transistor device coupled between the input terminal and the output terminal, the transistor device comprising: a drain contact electrically connected to a drain finger; a source contact electrically connected to a source finger; a diffusion area between the drain finger and the source finger to provide current between the drain finger and the source finger; the drain finger having a drain finger length extending along a Y axis and a plurality of different drain finger widths along the drain finger length such that current density is equal at each point along the drain finger length; and the source finger having a source finger length extending along the Y axis and a plurality of different source finger widths along the source finger length such that current density is equal at each point along the source finger length.

In Example 8, the subject matter of Example 7 can optionally include wherein the drain finger has a first drain finger width at a point along the drain finger length nearest the drain contact and at least one other drain finger width smaller than the first drain finger width, the at least one other drain finger width being at a point along the drain finger length further from the drain contact than the first drain finger width.

In Example 9, the subject matter of Example 8 can optionally include wherein the source finger has a first source finger width at a point along the source finger length nearest the source contact and at least one other source finger width smaller than the first source finger width, the at least one other source finger width being at a point along the source finger length further from the source contact than the first source finger width.

In Example 10, the subject matter of Example 8 can optionally include wherein the transistor device comprises a plurality of layers.

In Example 11, the subject matter of Example 10 can optionally include wherein the transistor device further comprises electrical connections between at least two of the plurality of layers, the electrical connections provided below at least one discrete width segment of the source finger and at least one discrete width segment of the drain finger.

In Example 12, the subject matter of any of Examples 7-11 can optionally include wherein a distance between the drain finger and the source finger is constant along the drain finger length and the source finger length.Example 13 is a user device including a front end module including: at least one antenna; at least one driver stage circuitry, the at least driver stage circuitry including: an input terminal and an output terminal; at least one transistor apparatus coupled between the input terminal and the output terminal, the transistor device comprising: a drain contact electrically connected to a drain finger; a source contact electrically connected to a source finger; a diffusion area between the drain finger and the source finger to provide current between the drain finger and the source finger; the drain finger having a drain finger length extending along a Y axis and a plurality of different drain finger widths along the drain finger length such that current density is equal at each point along the drain finger length; and the source finger having a source finger length extending along the Y axis and a plurality of different source finger widths along the source finger length such that current density is equal at each point along the source finger length.

In Example 14, the subject matter of Example 13 can optionally include wherein the drain finger has a first drain finger width at a point along the drain finger length nearest the drain contact and at least one other drain finger width smaller than the first drain finger width, the at least one other drain finger width being at a point along the drain finger length further from the drain contact than the first drain finger width.

In Example 15, the subject matter of Example 14 can optionally include wherein the source finger has a first source finger width at a point along the source finger length nearest the source contact and at least one other source finger width smaller than the first source finger width, the at least one other source finger width being at a point along the source finger length further from the source contact than the first source finger width.

In Example 16, the subject matter of Example 15 can optionally include wherein the transistor device comprises a plurality of layers.

In Example 17, the subject matter of Example 16 can optionally include wherein the transistor device further comprises electrical connections between at least two of the plurality of layers, the electrical connections provided below at least one discrete width segment of the source finger and at least one discrete width segment of the drain finger.

In Example 18, the subject matter of any of Examples 14-17 can optionally include wherein a distance between the drain finger and the source finger is constant along the drain finger length and the source finger length.

In Example 19, the subject matter of any of Examples 14-18 can optionally include two or more antennas.