Plastic-molded wide-bandgap power transistors and MMICS

Abstract

A transistor package comprising: - a circuit board; - a wide-bandgap transistor attached to the circuit board via a mold attachment material made of a sintered material having a bulk thermal conductivity (KT) between 40 W / mK-1 and 200 W / mK-1 and a flexural modulus (FM) of less than 20 GPa, the wide-bandgap transistor having a peak output power of more than 150 W when operating at a frequency of up to 3.8 GHz; and - an overmold that essentially surrounds the circuit board and the wide bandgap transistor.

Description

Area of ​​Revelation

[0001] The present disclosure relates to wide-bandgap semiconductor devices. More particularly, the present disclosure relates to overmolded wide-bandgap power transistors. background

[0002] As radio communications standards continue to evolve to ensure improvements in data rates and reliability, increasingly stringent requirements are being placed on the radio frequency (RF) power amplifiers (PAs) used to transmit radio signals. RF PAs compliant with the latest radio communications standards must exhibit a high degree of linearity and high gain over a wide bandwidth, while also being highly efficient to maintain the battery life of a mobile device in which they are integrated. Silicon (Si) and gallium arsenide (GaAs) RF PAs are well-known and widely used, but suffer from relatively narrow bandwidth and limited output power, characteristics inherent to the devices due to the narrow bandgap of their respective material systems.To improve the performance of a mobile terminal, wide-bandgap semiconductor devices for RF signal amplification are currently being investigated.

[0003] Wide-bandgap RF PAs, such as those constructed of silicon carbide (SiC) and gallium nitride (GaN), offer improvements in bandwidth, output power, and efficiency compared to their narrow-bandgap counterparts. However, due to the increased price associated with wide-bandgap devices, many mobile device manufacturers continue to rely on conventional RF PAs for RF circuit design and manufacturing. While there are numerous contributing factors to the increased price of wide-bandgap semiconductor devices, a large cost component is attributable to their packaging.

[0004] The Fig. 1 and Fig. 2 illustrates a conventional package 10 for a wide-bandgap semiconductor device 12. The conventional package 10 includes a ceramic body 14 and one or more metal contacts 16. Within the package 10, a trapped air bubble 18 surrounds the wide-bandgap semiconductor device 12, which is bonded to a metal substrate 20 via a mold attach material 22. One or more bond wires 24 connect the wide-bandgap semiconductor device 12 to a first metal contact 16A and a second metal contact 16B. The trapped air bubble 18 and the metal substrate 20 dissipate the heat generated by the wide-bandgap semiconductor device 12 while insulating and protecting the wide-bandgap semiconductor device 12 from the external environment.Although the ceramic body 14 and the metal substrate 20 of the conventional package 10 are suitable for protecting even a wide-bandgap semiconductor device and dissipating the heat generated by it, they are expensive to manufacture and thus drive up the cost of electronic package enclosing wide-bandgap semiconductor devices.

[0005] US 2014 / 0 084 432 A1 discloses a semiconductor device comprising a lead frame and a chip carrier mounted on the lead frame. The chip carrier is made of an electrically and thermally conductive material. A chip is attached to a surface of the chip carrier with a chip attachment material made of sintered silver, whose melting point is above 240°C. A first electrical connection connects the chip and the lead frame. A housing covers parts of the lead frame, the chip carrier, the chip, and the first electrical connection. Summary

[0006] The present disclosure relates to overmolded wide-bandgap power transistors. According to the invention, a transistor package includes a printed circuit board, a wide-bandgap transistor attached to the printed circuit board via a mold-attach material made of a sintered material, and an overmold surrounding the printed circuit board and the wide-bandgap transistor. The mold-attach material has a bulk thermal conductivity (KT) between 40 W / mK-1 and 200 W / mK-1 and a flexural modulus (FM) of less than 20 Gpa. The wide-bandgap transistor has a peak output power of more than 150 W when operating at a frequency of up to 3.8 GHz.The use of an overmold along with a wide-bandgap transistor in the transistor package allows the transistor package to achieve exceptionally high gain and bandwidth while keeping the transistor package manufacturing cost low.

[0007] According to one embodiment, the wide-bandgap transistor is a gallium nitride (GaN) transistor. In another embodiment, the wide-bandgap transistor is a GaN on silicon carbide (SiC) transistor and may also be a high electron mobility transistor (HEMT).

[0008] According to one embodiment, the efficiency of the transistor package is greater than about 30%, as measured for a typical radio communication standard signal, such as a Long Term Evolution (LTE) signal, with a peak-to-average factor of about 7.5 dB.

[0009] Those skilled in the art will appreciate the scope of the present disclosure, as well as additional aspects thereof, after reading the following detailed description of the preferred embodiments in conjunction with the accompanying drawings. Short description of the drawings

[0010] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure. Fig. 1 is an isometric view of a conventional electronics housing package for a semiconductor device. Fig. 2 is a cross-sectional view of the conventional electronic housing package for a semiconductor device used in Fig. 1 is shown. Fig. 3 is an isometric view of an electronics housing package for a wide bandgap semiconductor device according to an embodiment of the present disclosure. Fig. 4 is a cross-sectional view of the electronics housing package used in Fig. 3, according to one embodiment of the present disclosure. Fig. 5 is a schematic diagram of a radio frequency (RF) transmission chain according to an embodiment of the present disclosure. The Fig. 6A-6C are schematic diagrams of a transistor package for use in the RF transmission chain in Fig. 5 according to an embodiment of the present disclosure. The Fig. 7A-7C are schematic diagrams of an amplifier housing package for use in the RF transmission chain in Fig. 5 according to an additional embodiment of the present disclosure. Fig. Figure 8 is a schematic diagram of a bandwidth limiting matching network for use in transistor package packaging in the Fig. 6A-6C and / or the amplifier housing packaging in the Fig. 7A-7C according to an embodiment of the present disclosure. Fig. Figure 9 is a graph showing the peak output power response of the transistor package in the Fig. 6A-6C and / or the amplifier housing packaging in the Fig. 7A-7C according to an embodiment of the present disclosure. Detailed description

[0011] The embodiments set forth below provide the information necessary to enable one skilled in the art to practice the embodiments and illustrate the best mode for practicing the embodiments. Upon reading the following description with reference to the accompanying drawings, one skilled in the art will understand the principles of the disclosure and recognize applications of these concepts not specifically set forth herein. These concepts and applications are understood to be within the scope of the disclosure and the appended claims.

[0012] It should be understood that although the terms "first," "second," etc., may be used herein to describe various elements, these elements are not intended to be limited by these terms. These terms are used only to distinguish the elements from one another. For example, a first element could be referred to as a second element, and similarly, a second element could be referred to as a first element, without departing from the scope of the present disclosure. As used herein, the term "and / or" includes any combination of one or more of the associated listed parts.

[0013] It is to be understood that when an element, such as a layer, region, or substrate, is referred to as being "on" or extending "onto" another element, it may be directly on or extending onto the other element, or there may also be intervening elements. Conversely, when an element is referred to as being "directly on" or extending "directly onto" another element, no intervening elements are present. Similarly, when an element, such as a layer, region, or substrate, is referred to as being "over" or extending "across" another element, it is to be understood that it may be directly above or extending over the other element, or there may also be intervening elements.Conversely, when an element is described as being "directly above" or extending "directly over" another element, no intervening elements are present. It is also understood that when an element is described as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intervening elements. Conversely, when an element is described as being "directly connected" or "directly coupled" to another element, no intervening elements are present.

[0014] Relative terms such as "below," "above," "upper," "lower," "horizontal," or "vertical" may be used herein to describe the relationship of one element of one layer or region to another element of another layer or region, as illustrated in the figures. It is understood that these and the terms discussed above are intended to encompass various orientations of the device in addition to the orientation illustrated in the figures.

[0015] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context expressly requires otherwise. It is further understood that the terms "comprises," "comprising," "includes," and / or "including," when used herein, indicate the presence of specified features of integers, steps, acts, elements, and / or components, but do not preclude the presence or addition of one or more other features of integers, steps, acts, elements, components, and / or groups thereof.

[0016] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by a person of ordinary skill in the art to which this disclosure pertains. It is further understood that the terms used herein should be interpreted to have a meaning consistent with their meaning in the context of this specification and the related art and should not be idealized or interpreted in an overly formal manner, except as expressly stated herein.

[0017] The Fig. 3 and Fig. 4 illustrate an electronics package 26 suitable for use with one or more wide-bandgap semiconductor devices 28 according to an embodiment of the present disclosure. In particular, Fig. 3 an isometric view of the electronics housing 26, while Fig. 4 shows a cross-sectional view of the electronics package 26. The electronics package 26 includes an overmold 30, one or more input / output pins 32, and a circuit board 34. The overmold 30 may substantially surround the one or more wide-bandgap semiconductor devices 28, which are mounted on the circuit board 34 with a mold-attach material 38. The overmold 30 may be comprised of a plastic or plastic-polymer compound injection-molded around the circuit board 34 and the one or more wide-bandgap semiconductor devices 28, thus providing protection from the external environment. The one or more wide-bandgap semiconductor devices 28 may be coupled to the one or more input / output pins 32 via bond wires 40.

[0018] The maximum temperature value of conventional electronics package packaging technologies using overmolding has been capped at 150°C due to the materials used in conventional electronics package packaging. Therefore, conventional electronics package packaging technologies are generally only suitable for narrow-bandgap devices with a peak output power of less than 150 W and an operating frequency of less than 2.2 GHz. Due to the inherently high power density of wide-bandgap devices, the package packaging of a wide-bandgap device is subject to significantly more stringent requirements than the package packaging of a similar narrow-bandgap device.In particular, the high power density of a wide-bandgap semiconductor device results from the large amount of heat generated by the device, which must be adequately dissipated by the package to avoid damage to the device. Furthermore, due to the large amount of heat generated, the portion of the package in contact with a wide-bandgap semiconductor device should avoid excessive expansion and / or contraction during heating and cooling, as this may damage the one or more devices in contact with the package.

[0019] Since wide-bandgap semiconductor devices often operate at peak output powers exceeding 200 W, frequencies up to 3.8 GHz, and temperatures exceeding 200°C, conventional electronics package packaging technologies are not suitable for wide-bandgap devices rated at their full capacity. In designing an electronics package suitable for a wide-bandgap semiconductor device, the inventors discovered four key properties for determining the suitability of a material to be used for overmolding. Specifically, the inventors discovered that the glass transition temperature (T G ), the flexural modulus (F M ), the coefficient of thermal expansion (CTE) and the moisture absorption rate (A R ) of the material used for the overmolding 30 are critical to the performance and durability of the electronics housing package 26.

[0020] The glass transition temperature (T G ) of a material indicates the temperature at which a change of state from a solid to a liquid begins, and it is often used by electronics housing packaging designers to characterize the material's thermal capabilities. The flexural modulus (F M ) of a material is the ratio of strain to stress in the flexural deformation of the material (for example, the tendency of the material to bend). The coefficient of thermal expansion (CTE) of a material indicates how much the size of a material changes as a result of changes in the material's temperature. The moisture absorption rate (A R ) of a material indicates the amount of moisture (in percentage) that a material will absorb under certain conditions.

[0021] In general, an increase in the glass transition temperature (T G) of a particular material allow the material to be exposed to a higher temperature without damaging the structure of the material. However, while the glass transition temperature (T G ) of a material increases, this is also the case with the flexural modulus (F M ), the coefficient of thermal expansion (CTE) and the moisture absorption rate (A R ) of the material. In designing the electronics housing package 26, the inventors discovered that the use of materials with a high flexural modulus (F M ), a high coefficient of thermal expansion (CTE) and / or a high moisture absorption rate (A R) for the overmold 30 may result in delamination of the overmold 30 from the circuit board 34 and / or cracking or other structural damage to the one or more wide-bandgap semiconductor devices 28 in contact with the overmold 30 due to expansion and contraction of the overmold 30 as the temperature of the one or more wide-bandgap semiconductor devices 28 changes over time. Therefore, a balance must be found between the glass transition temperature (T G ), the flexural modulus (F M ), the coefficient of thermal expansion (CTE) and the moisture absorption rate (A R ) of the material used for the recasting 30.

[0022] In one embodiment, the overmold 30 of the electronics housing package 26 may have a glass transition temperature (T G ) between approximately 135°C and 400°C, a flexural modulus (F M) below approximately 20 GPa, a coefficient of thermal expansion (CTE) below approximately 50 ppm / °C at temperatures above the glass transition temperature and below approximately 18 ppm / °C at temperatures below the glass transition temperature, and a moisture absorption rate (A R ) of less than approximately 0.5%.

[0023] In one embodiment, the overmold 30 is made from part no.

[0024] G720A molded, manufactured by Sumitomo Bakelite in Fukuoka, Japan, the datasheet of which is incorporated herein in its entirety by reference. By using an overmold 30 for the electronics housing package 26 with a glass transition temperature (T G ) between approximately 135°C and 400°C, a flexural modulus (F M) below approximately 20 GPa, a coefficient of thermal expansion (CTE) below approximately 50 ppm / °C at temperatures above the glass transition temperature and below approximately 18 ppm / °C at temperatures below the glass transition temperature, and a moisture absorption rate (A R ) of less than about 0.5%, the electronics housing package 26 may be suitable for containing the one or more wide bandgap semiconductor devices 28. In particular, the high glass transition temperature (T G ) of the overmold 30 of the electronics housing package 26 to dissipate the heat generated by the one or more wide-bandgap semiconductor devices 28 within the electronics housing package 26 without structural damage thereto, while maintaining the low flexural modulus (F M ) the coefficient of thermal expansion (CTE) and the moisture absorption rate (A R) of the overmold 30 prevent damage to the one or more wide bandgap semiconductor devices 28 that may be caused due to deformation of the portion of the overmold 30 in contact with the one or more wide bandgap semiconductor devices 28 due to thermal expansion and / or contraction.

[0025] In addition to the properties discussed above with respect to the overmold 30, the inventors also made similar discoveries with respect to the mold attachment material 38. Specifically, the inventors discovered that the bulk thermal conductivity (K T ) and the flexural modulus (F M) of the mold-attachment material 38 are crucial for the performance and durability of the electronics housing package 26. According to the invention, the mold-attachment material 38 is a sintered material, such as a sintered silver material, wherein the sintered material has a bulk thermal conductivity (K T ) between approximately 40 W / mK and 200 W / mK and a flexural modulus (F M ) of less than about 20 GPa. In one embodiment, the mold-attach material 38 is Part No. D591-3B, manufactured by Alpha Advanced Materials of Suwanee, Georgia, the data sheet of which is incorporated herein by reference in its entirety. By using a mold-attach material 38 for the electronics housing package 26 having a bulk thermal conductivity (K T ) between approximately 40 W / mK and 200 W / mK and a flexural modulus (F M) of less than about 20 GPa, the electronics housing package 26 may be suitable for housing the one or more wide bandgap semiconductor devices 28. In particular, the high bulk thermal conductivity (K T ) of the mold attachment material 38 ensures that an appropriate amount of heat is conducted away from the one or more semiconductor devices 28 while maintaining the low flexural modulus (F M ) of the mold attachment material 38 prevents damage to the one or more wide bandgap semiconductor devices 28 that may be caused by deformation of the portion of the mold attachment material 38 that is in contact with the one or more wide bandgap semiconductor devices 28 due to thermal expansion and / or contraction.

[0026] During the design of the electronics housing package 26, the inventors further discovered that the upper limit of the flexural modulus (F M) of the mold-attach material (28) may depend on the area of ​​the one or more wide-bandgap semiconductor devices 28 in the electronics housing package 26. Accordingly, the particular material used as the mold-attach material 28 may vary depending on the area of ​​the one or more wide-bandgap semiconductor devices 28 in the electronics housing package 26. In an embodiment in which the one or more wide-bandgap semiconductor devices 28 have an area of ​​less than 4 mm x 4 mm, the flexural modulus (F M ) of the mold attachment material 28 may be less than approximately 6 GPa. In a further embodiment in which the one or more wide bandgap semiconductor devices 28 have an area of ​​less than 2 mm x 2 mm, the flexural modulus

[0027] (F M) of the mold attachment material 28 may be less than approximately 10 GPa. In yet another embodiment, in which the one or more wide bandgap semiconductor devices 28 have an area of ​​less than 1 mm x 1 mm, the flexural modulus (F M ) of the mold fastening material 28 may be less than approximately 20 GPa. Similarly, the upper limit of the flexural modulus (F M ), the coefficient of thermal expansion (CTE) and the moisture absorption rate (A R ) of the overmold 30 may vary depending on the area of ​​the one or more wide bandgap semiconductor devices 28 in the electronics package 26.

[0028] The input / output pins 32 and the circuit board 34 may be made of copper, copper alloy, or the like, but any suitable materials may be used for the input / output pins 32 without departing from the principles of the present disclosure.

[0029] It should be noted that the use of the electronics package 26 having the above-mentioned properties enables the housing of one or more wide-bandgap semiconductor devices 28 while significantly reducing the manufacturing cost of the electronics package 26. Since the housing of the wide-bandgap devices represents a large cost component, the use of the electronics package 26 can significantly reduce the cost of electronics package utilizing wide-bandgap devices. Furthermore, due to the properties discussed above with respect to the electronics package 26, the one or more wide-bandgap semiconductor devices 28 can operate at full capacity without deterioration due to their housing.In one embodiment, the one or more wide-bandgap semiconductor devices are 28 wide-bandgap transistors configured to operate with a peak output power of approximately 150 W at frequencies above 2.2 GHz and up to 3.8 GHz. In another embodiment, the one or more wide-bandgap semiconductor devices are 28 wide-bandgap transistors configured to operate with a peak output power of approximately 200 W and a frequency of up to 3.8 GHz. In yet another embodiment, the one or more wide-bandgap semiconductor devices are 28 wide-bandgap transistors configured to operate with a peak output power of approximately 250 W and a frequency of up to 3.8 GHz.

[0030] In one embodiment, the electronics housing package 26 complies with the Joint Electron Device Engineering Council (JEDEC) environmental standards for moisture sensitivity (MSL-3).

[0031] Fig. 5 shows a radio frequency (RF) transmission chain 42 according to an embodiment of the present disclosure. The RF transmission chain 42 includes an input node RF_IN, an antenna 44, an input stage RF power amplifier (PA) 46, an output stage RF PA 48, and a plurality of matching networks 50. Specifically, the RF transmission chain 42 includes a first matching network 50A connected between the input node RF_IN and the input stage RF PA 46, a second matching network 50B connected between the input stage RF PA 46 and the output stage RF PA 48, and a third matching network 50C connected between the output stage RF PA 48 and the antenna 44. During operation, a modulated signal is provided to the input node RF_IN, where it is provided to the input stage RF PA 46 by the first matching network 50A.The modulated signal is amplified by the input stage RF PA 46 and delivered to the output stage RF PA 48 through the second matching network 50B. The output stage RF PA 48 then further amplifies the modulated signal to generate an RF output signal suitable for transmission via the antenna 44 and delivers the RF output signal to the antenna 44 through the third matching network 50C.

[0032] The matching networks 50 may be provided to match an impedance between two different components and thus ensure stable operation of the RF transmission chain 42 with minimal losses due to, for example, a high voltage standing wave ratio (VSWR). Although three different matching networks 50 are illustrated in the RF transmission chain 42, any number of matching networks 50 may be used in the RF transmission chain 42 without departing from the principles of the present disclosure. Furthermore, although only one input stage RF PA 46 and one output stage RF PA 48 are used in Fig. 5, any number of input stage or output stage RF PAs may be used in the RF transmission chain 42 without departing from the principles of the present disclosure.

[0033] As discussed above, the RF transmission chain 42 requires a high degree of linearity and high gain over a wide bandwidth while maintaining high efficiency. Therefore, the input stage RF PA 46, the output stage RF PA 48, or both can be wide-bandgap RF PAs to increase the performance of the RF transmission chain 42.

[0034] Fig. Figure 6A shows a transistor package 52 suitable for use as the input stage RF PA 46, the output stage RF PA 48, or both in the RF transmission chain 42 shown in Fig. 5 according to one embodiment of the present disclosure. The transistor package 52 includes an input node RF_IN, a wide bandgap transistor 54, a bandwidth limiting matching network 56, and an output node RF_OUT. The bandwidth limiting matching network 56 is connected between the input node RF_IN and the wide bandgap transistor 54. The wide bandgap transistor 54 is connected between the bandwidth limiting matching network 56 and the output node RF_OUT. As stated above, the use of the wide bandgap transistor 50 can provide a high degree of linearity and large gain over a wide bandwidth.In certain cases, the bandwidth of the transistor package 52 may be problematic, for example, due to one or more spectral masking requirements (such as those required by a radio communications standard that the transistor package 52 should conform to). Therefore, to reduce signal transmissions outside a predefined frequency band or bands, the bandwidth-limiting matching network 56 is provided to attenuate the gain of the wide-bandgap transistor 54 when it operates outside the predefined frequency band or bands. In addition to attenuating the gain of the wide-bandgap transistor 54 outside the predefined frequency band or bands, the bandwidth-limiting matching network 56 may also match an external impedance coupled to the transistor package 52.The details of the bandwidth limiting adaptation network 56 are discussed in more detail below.

[0035] In one embodiment, the wide bandgap transistor 54 is a gallium nitride (GaN) transistor. In another embodiment, the wide bandgap transistor 54 is a gallium nitride (GaN) on silicon carbide (SiC) transistor. In other embodiments, any number of wide bandgap semiconductor material systems may be used for the wide bandgap transistor 54, all of which are contemplated herein. The wide bandgap transistor 54 may be a high electron mobility transistor (HEMT). Accordingly, the bandwidth limiting adjustment network 56 may be connected between the input node RF_IN and a gate contact (G) of the wide bandgap transistor 54, wherein the output node RF_OUT may be coupled to a drain contact (D) of the wide bandgap transistor 54, and a source contact (S) of the wide bandgap transistor 54 may be coupled to ground.In other embodiments, the wide bandgap transistor 54 may be a field effect transistor (FET), a MOSFET transistor, a bipolar junction transistor (BJT), an insulated gate bipolar transistor (IGBT), or the like.

[0036] The transistor package 52 is an integrated circuit packaged as a separate component. In other words, the transistor package 52 is suitable as a replacement component for one or more conventional RF PAs. In one embodiment, the transistor package 52 is a monolithic integrated circuit. For the purposes of this application, a monolithic integrated circuit is an integrated circuit formed on a single semiconductor die. In another embodiment, the transistor package 52 is a hybrid integrated circuit. For the purposes of this application, a hybrid integrated circuit is an integrated circuit in which multiple interconnected semiconductor dies are provided within a single package on a substrate.The provision of the bandwidth-limiting matching network 56 within the transistor package 52 enables the transistor package 52 to achieve a frequency response similar to that of a conventional narrow-bandgap RF PA, while maintaining greater gain and efficiency with lower losses than its conventional counterpart. Accordingly, the transistor package 52 can be used as a direct replacement for a conventional RF PA, thereby improving the performance of an RF transmission chain incorporating the transistor package 52 while requiring little or no redesign of the RF circuitry connected to the transistor package 52.

[0037] In one embodiment, the transistor package 52 is an overmold package as described above with reference to the Fig. 3 and Fig. 4. Accordingly, the transistor package 52 may comprise a plastic overmold having a glass transition temperature (T G ) between approximately 135°C and 400°C, a flexural modulus (F M ) below approximately 20 GPa, a coefficient of thermal expansion (CTE) below approximately 50 ppm / °C at temperatures above the glass transition temperature and below approximately 18 ppm / °C at temperatures below the glass transition temperature, and a moisture absorption rate (A R ) of less than about 0.5%. Further, the transistor package 52 may be connected to a printed circuit board using a molded attachment material having a bulk thermal conductivity (K T ) between approximately 40 W / mK and 200 W / mK and a flexural modulus (F M) of less than approximately 20 GPa. This allows the cost of the transistor package 52 to be kept low while providing the performance improvements mentioned above.

[0038] In one embodiment, the transistor package 52 has a peak output power of greater than 54 dBm (or 250 W) within the predefined frequency band or bands. Furthermore, due to the bandwidth limiting matching network 56, the transistor package 52 has an average output power of less than 48 W outside the predefined frequency band or bands. The bandwidth limiting matching network 56 can provide a gain roll-off of greater than 0.5 dB within 200 MHz of the predefined frequency band or bands and a gain roll-off of 7.5 dB within 300 MHz of the predefined frequency band or bands.Accordingly, the transistor package 52 can provide more than 240 W peak output power in the predefined frequency band or bands and less than 48 W average output power outside the predefined frequency band or bands, wherein the average output power of the transistor package 52 is measured according to a peak-to-average factor (PAR) for WCDMA of 7.5 dB.Furthermore, the transistor package 52 can provide a peak output power of more than 240 W in the predefined frequency band(s) and an average output power of less than 48 W outside the predefined frequency band(s). The average output power of the transistor package 52 is defined as the output power of the transistor package 52 when the transistor package 52 is operating at maximum capacity with a 20% duty cycle. In one embodiment, the transistor package 52 can have an average output power of more than 80 W at 2.6 GHz with a 50% gain efficiency while transmitting 7.5 dB PAR Long Term Evolution (LTE) signals at 50 V, and it can have 17 dB gain at the rated output power.In an additional embodiment, the transistor package 52 may have a saturation efficiency (P. SAT ) of more than 65%.

[0039] In one embodiment, the predefined frequency band or bands are those used for RF communications. Therefore, the bandwidth limiting matching network 56 can match one or more impedances at the RF frequencies while simultaneously limiting the bandwidth of the wide bandgap transistor 54. In one embodiment, the predefined frequency band or bands include one or more of the frequencies between 690-960 MHz, 1800-2300 MHz, or 2300-2700 MHz.

[0040] Fig. 6B shows the transistor package 52 according to another embodiment of the present disclosure. The transistor package 52 in Fig. 6B is similar to the transistor package 52 shown in Fig. 6A, but includes the bandwidth limiting matching network 56 in a coupling between the wide bandgap transistor 54 and the output node RF_OUT, rather than in a coupling between the input node RF_IN and the wide bandgap transistor 54. The transistor package 52 may operate substantially similarly to the transistor package 52 in Fig. 6A. That is, the bandwidth limiting adjustment network 56 may reduce the gain response of the wide bandgap transistor 54 outside of a predefined frequency band or predefined frequency bands to ensure that the transistor package 52 meets one or more spectral masking requirements.

[0041] In an embodiment in which the wide bandgap transistor 54 is a HEMT, the bandwidth limiting matching network 56 is connected between the drain contact (D) of the wide bandgap transistor 54 and the output node RF_OUT, the input node RF_IN is coupled to the gate contact (G) of the wide bandgap transistor 54, and the source contact (S) of the wide bandgap transistor 54 is coupled to ground.

[0042] Fig. 6C shows the transistor package 52 according to another embodiment of the present disclosure. The transistor package 52 shown in Fig. 6C is similar to the transistor package 52 in Fig. 6A and Fig. 6B, but includes both a first bandwidth limiting adjustment network 56A connected between the input node RF_IN and the wide bandgap transistor 54, and a second bandwidth limiting adjustment network 56B connected between the wide bandgap transistor 54 and the output node RF_OUT. The transistor package 52 may operate in a substantially similar manner to the transistor package 52 in Fig. 6A and Fig. 6B. That is, the first bandwidth limiting adjustment network 56A and the second bandwidth limiting adjustment network 56B may reduce the gain response of a wide bandgap transistor 54 outside of a predefined frequency band or predefined frequency bands to ensure that the transistor package 52 meets one or more spectral masking requirements.

[0043] In an embodiment in which the wide bandgap transistor 54 is a HEMT, the first bandwidth limiting adjustment network 56A is connected between the input node RF_IN and the gate contact (G) of the wide bandgap transistor 54, the second bandwidth limiting adjustment network 56B is connected between the drain contact (D) of the wide bandgap transistor 54 and the output node RF_OUT, and the source contact (S) of the wide bandgap transistor 54 is coupled to ground.

[0044] Fig. Figure 7A shows an amplifier package 58 suitable for use as an input stage RF PA 46, an output stage RF PA 48, or both in the RF transmission chain 42 used in Fig. 5, according to one embodiment of the present disclosure. The amplifier package 58 includes a first wide bandgap transistor 60A, a second wide bandgap transistor 60B, and one or more bandwidth limiting matching networks 62. The bandwidth limiting matching networks 62 are connected between an input node RF_IN and the wide bandgap transistors 60. In some embodiments, the first wide bandgap transistor 60A and the second wide bandgap transistor 60B are arranged in a Doherty configuration. Providing multiple wide bandgap transistors 60 in the amplifier package 58 may increase the gain and performance of the amplifier package 59 in some applications.As stated above, the first wide-bandgap transistor 60A and the second wide-bandgap transistor 60B can ensure a high degree of linearity and high gain over a wide bandwidth. In some cases, the bandwidth of the amplifier package 58 may be problematic, for example, due to one or more spectral masking requirements. Accordingly, to reduce signal transmissions outside a predefined frequency band or bands, the bandwidth limiting matching networks 62 are provided to attenuate the gain of the first wide-bandgap transistor 60A and the second wide-bandgap transistor 60B when operating outside the predefined frequency band or bands.In addition to attenuating the gain of the first wide bandgap transistor 60A and the second wide bandgap transistor 60B outside the predefined frequency band or bands, the bandwidth limiting matching networks 62 may also match an external impedance coupled to the amplifier package 58.

[0045] The details of the bandwidth limiting adaptation networks 62 are discussed in more detail below.

[0046] In one embodiment, the first wide-bandgap transistor 60A and the second wide-bandgap transistor 60B are GaN transistors. In another embodiment, the first wide-bandgap transistor 60A and the second wide-bandgap transistor 60B are GaN-based SiC transistors. A variety of suitable broadband semiconductor material systems exist for the first wide-bandgap transistor 60A and the second wide-bandgap transistor 60B, all of which are contemplated herein. The first wide-bandgap transistor 60A and the second wide-bandgap transistor 60B may be HEMTs.Accordingly, a first bandwidth limiting adjustment network 62A may be connected between the input node RF_IN and a gate contact (G) of the first wide bandgap transistor 60A, a second bandwidth limiting adjustment network 62B may be connected between the input node RF_IN and a gate contact (G) of the second wide bandgap transistor 60B, and a drain contact (D) of the first wide bandgap transistor 60A may be coupled to the output node RF_OUT, a source contact (S) of the first wide bandgap transistor may be coupled to ground, a drain contact (D) of the second wide bandgap transistor 60B may be coupled to the output node RF_OUT, and a source contact (S) of the second wide bandgap transistor 60B may be coupled to ground.In other embodiments, the first wide bandgap transistor 60A and the second wide bandgap transistor 60B may be FETs, MOSFETs, BJTs, IGBTs, or the like.

[0047] In one embodiment, the amplifier package 58 is an integrated circuit packaged as a separate component. In other words, the amplifier package 58 is suitable as a replacement device for one or more conventional RF PAs. In one embodiment, the amplifier package 58 is a monolithic integrated circuit. In another embodiment, the amplifier package 58 is a hybrid integrated circuit. The provision of the bandwidth limiting matching network 62 within the amplifier package 58 enables the amplifier package 58 to have a similar frequency response to a conventional narrow-bandgap RF PA, while maintaining greater gain and efficiency while maintaining lower losses than its conventional counterpart.Therefore, the amplifier package 58 can be used as a direct replacement for a conventional RF PA, thereby improving the performance of an RF transmission chain incorporating the amplifier package 58, with little or no redesign of the RF circuitry connected to the amplifier package 58 being required.

[0048] In one embodiment, the transistor package 52 is an overmold package as described above with reference to the Fig. 3 and Fig. 4. Accordingly, the transistor package 52 may comprise a plastic overmold having a glass transition temperature (T G ) between approximately 135°C and 400°C, a flexural modulus (F M) below approximately 20 GPa, a coefficient of thermal expansion (CTE) below approximately 50 ppm / °C at temperatures above the glass transition temperature and below approximately 18 ppm / °C at temperatures below the glass transition temperature, and a moisture absorption rate (A R ) of less than about 0.5%. Further, the transistor package 52 may be bonded to a printed circuit board with a mold attachment material having a bulk thermal conductivity (K T ) between approximately 40 W / mK and 200 W / mK and a flexural modulus (F M ) of less than approximately 20 GPa. This allows the cost of the transistor package 52 to be kept low while simultaneously enabling the performance improvements mentioned above.

[0049] In one embodiment, amplifier package 58 has a peak output power greater than 54 dBm (or 250 W) in the predefined band or bands. Furthermore, due to bandwidth limiting networks 62, amplifier package 58 has an average output power of less than 48 W outside the predefined band or bands. Bandwidth limiting matching networks 62 can provide a gain roll-off of 0.5 dB within 200 MHz of the predefined band or bands and a gain roll-off of 7.5 dB within 300 MHz of the predefined band or bands.Accordingly, the amplifier package 58 can provide more than 240 W peak output power in the predefined band or bands and less than 48 W average output power outside the predefined band or bands, wherein the average output power of the amplifier package 58 is measured corresponding to a 7.5 dB PAR for WCDMA. Further, the amplifier package 58 can provide: a peak output power of more than 240 W in the predefined band or bands and an average output power of less than 48 W outside the predefined band or bands, wherein the average output power of the amplifier package 58 is defined as the output power of the amplifier package 58 at which the amplifier package 58 is operated at maximum capacity with a 20% duty cycle.In one embodiment, the amplifier package 58 can provide an average output power above 80 W at 2.6 GHz with 50 percent drain efficiency while transmitting 7.5 dB PAR Long Term Evolution (LTE) signals at 50 V and at 17 dB gain at the nominal output power. In an additional embodiment, the amplifier package 58 can provide a saturation (P SAT -)Efficiency of more than 65%.

[0050] In one embodiment, the predefined frequency band(s) are frequency bands used for RF communications. Therefore, the bandwidth limiting matching networks 62 can pre-match one or more impedances at the RF frequencies while limiting the bandwidth of the wide bandgap transistors 60. In one embodiment, the predefined frequency band(s) include one or more of the frequencies between 690-960 MHz, 1800-2300 MHz, or 2300-2700 MHz.

[0051] Fig. 7B shows the amplifier package 58 according to another embodiment of the present disclosure. Fig. The amplifier package 58 shown in Figure 7B is similar to the one shown in Fig. 7A, however, includes the bandwidth limiting matching networks 62 coupled between the wide bandgap transistors 60 and the output node RF_OUT, rather than between an input node RF_IN and the wide bandgap transistors 60. The amplifier package 58 may operate in a substantially similar manner to the amplifier package 58 in Fig. 7A. That is, the bandwidth limiting matching networks 62 may attenuate the gain response of the first wide bandgap transistor 60A and the second wide bandgap transistor 60B outside of a predefined frequency band or predefined frequency bands to ensure that the amplifier package 58 meets one or more spectral masking requirements.

[0052] In an embodiment in which the first wide bandgap transistor 60A and the second wide bandgap transistor 60B are HEMTs, the input node RF_IN is coupled to the gate contact (G) of the first wide bandgap transistor 60A and the gate contact (G) of the second wide bandgap transistor 60B, the source contact (S) of the first wide bandgap transistor 60A being coupled to ground, the drain contact (D) of the first wide bandgap transistor 60A being coupled to the output node RF_OUT via the first bandwidth limiting matching network 62A, the drain contact (D) of the second wide bandgap transistor 60B being coupled to the output node RF_OUT via the second bandwidth limiting matching network 62B, and the source contact (S) of the second Wide bandgap transistor 60B is coupled to ground.

[0053] Fig. Figure 7C shows the amplifier package 58 according to another embodiment of the present disclosure. Fig. The amplifier package 58 shown in Figure 7C is essentially similar to that shown in Fig. 7A and Fig. 7B, but further includes a third bandwidth limiting matching network 62C and a fourth bandwidth limiting matching network 62D. The amplifier package 58 may operate in a substantially similar manner to the amplifier package 58 described above with reference to Fig. 5A and Fig. 5B. That is, the bandwidth limiting matching networks 62 may attenuate the gain response of the first wide bandgap transistor 60A and the second wide bandgap transistor 60B to ensure that the amplifier package 58 meets one or more spectral masking requirements.

[0054] In an embodiment in which the first wide bandgap transistor 60A and the second wide bandgap transistor 60B are HEMTs, the first bandwidth limiting adjustment network 62A is connected between the input node RF_IN and the gate contact (G) of the first wide bandgap transistor 60A, the second bandwidth limiting adjustment network 62B is connected between the drain contact (D) of the first wide bandgap transistor 60A and the output node RF_OUT, the source contact (S) of the first wide bandgap transistor 60A is coupled to ground, the third bandwidth limiting adjustment network 62C is connected between the input node RF_IN and the gate contact (G) of the second wide bandgap transistor 62B, the fourth bandwidth limiting adjustment network 62D is connected between the drain contact (D) of the second wide bandgap transistor 60B and the output node RF_OUT,and the source contact (S) of the second wide-bandgap transistor 60B is coupled to ground.,

[0055] Fig. Figure 8 shows an exemplary bandwidth limiting adaptation network 64 that can be used as the bandwidth limiting adaptation network 56 shown in the Fig. 6A-6C and / or as the bandwidth limiting adaptation networks 62 shown in the Fig. 7A-7C, according to one embodiment of the present disclosure. The bandwidth limiting adjustment network 64 includes an input node RF_IN, a first inductor L1 connected between the input node RF_IN and an intermediate node 66, a second inductor L2, and a first capacitance C1 connected in series between the intermediate node 66 and ground, a third inductor L3 connected between the intermediate node 66 and an output node RF_OUT, and a second capacitance C2 connected between the output node RF_OUT and ground. The second inductor L2 and the first capacitance C1 can act as a notch-blocking filter that can attenuate the gain of a connected component at a predefined frequency.The predefined frequency is determined by the inductance and / or capacitance selected for the various components in bandwidth limiting matching network 64. The additional components in bandwidth limiting matching network 64 can match an impedance applied to input node RF_IN with an impedance applied to output node RF_OUT to reduce interference in the circuit in which bandwidth limiting matching network 64 is integrated.

[0056] Although the bandwidth limiting matching network 64 is illustrated as including a particular number of components arranged in a particular manner, there are many different configurations for both the number and arrangement of components in the bandwidth limiting matching network 64, all of which are contemplated herein. The number and arrangement of components in the bandwidth limiting matching network 64 may vary depending on the predefined frequency band or bands over which gain response is desired for the transistor package 53 and / or the amplifier package 58.

[0057] Fig. Figure 9 is a graph showing the peak output power response of the transistor package 52 in the Fig. 4A-4C, where the predefined frequency band is between approximately 2.4 GHz and 2.7 GHz. The solid line in Fig. Figure 9 shows the peak output power response of the transistor package 52 including the bandwidth limiting matching network 56, while the dotted line represents the power response of the transistor package 52 without the bandwidth limiting matching network 56. As in Fig.As shown in Figure 9, the power response of the transistor package 52 including the bandwidth-limiting matching network 56 falls at a significantly accelerated rate, beginning at approximately 2.7 GHz, while the power response of the transistor package 52 without the bandwidth-limiting matching network 56 remains relatively linear. Furthermore, the performance of the transistor package 52 is high in the predefined frequency band, peaking at approximately 55 dB. Therefore, the transistor package 52 is readily capable of meeting one or more spectral masking requirements with minimal impact on the in-band performance of the transistor package 52.

Claims

[1] A transistor package comprising: - a circuit board; - a wide-bandgap transistor attached to the circuit board via a mold attachment material made of a sintered material having a bulk thermal conductivity (KT) between 40 W / mK-1 and 200 W / mK-1 and a flexural modulus (FM) of less than 20 GPa, the wide-bandgap transistor having a peak output power of more than 150 W when operating at a frequency of up to 3.8 GHz; and - an overmold that essentially surrounds the circuit board and the wide bandgap transistor. [2] The transistor housing package of claim 1, wherein the wide bandgap transistor is a gallium nitride (GaN) transistor. [3] The transistor housing package of claim 1, wherein the wide bandgap transistor is a gallium nitride (GaN) on silicon carbide (SiC) transistor. [4] The transistor housing package of claim 3, wherein the wide bandgap transistor is a high electron mobility transistor (HEMT). [5] The transistor housing package of claim 1, wherein the peak output power of the wide bandgap transistor is less than 1 kW. [6] The transistor housing package of claim 1, wherein an efficiency of the wide bandgap transistor is more than 30%. [7] The transistor housing package according to claim 1, wherein the overmold is plastic. [8] The transistor package according to claim 1, wherein the transistor package is a monolithic integrated circuit. [9] The transistor package of claim 1, wherein the transistor package is a hybrid integrated circuit. [10] The transistor housing package of claim 1, wherein the wide bandgap transistor operates at temperatures greater than 150°C. [11] The transistor housing package of claim 1, wherein the overmold has a glass transition temperature of greater than 135°C and a flexural modulus of less than 20 GPa. [12] The transistor housing package of claim 11, wherein the overmold has a coefficient of thermal expansion of less than 50 ppm / °C at temperatures above the glass transition temperature and a coefficient of thermal expansion of less than 18 ppm / °C at temperatures below the glass transition temperature. [13] The transistor housing package according to claim 12, wherein the overmold has a moisture absorption rate of less than 0.5%. [14] An overmolded transistor package including a wide-bandgap transistor having a peak output power of more than 150 W when operating at frequencies above 2.2 GHz and up to 3.8 GHz, attached to a mold mount material made of a sintered material having a bulk thermal conductivity (KT) between 40 W / mK-1 to 200 W / mK-1 and a flexural modulus (FM) of less than 20 GPa. [15] The overmold transistor package of claim 14, wherein the wide bandgap transistor is a gallium nitride (GaN) transistor. [16] The overmold transistor package of claim 14, wherein the wide bandgap transistor is a gallium nitride (GaN) on silicon carbide (SiC) transistor. [17] The overmold transistor package of claim 16, wherein the wide bandgap transistor is a high electron mobility transistor (HEMT). [18] The overmold transistor package of claim 14, wherein the peak output power of the wide bandgap transistor is less than 1 kW. [19] The overmold transistor package according to claim 14, wherein the efficiency of the overmold transistor package is greater than 30%. [20] The overmold transistor package according to claim 14, wherein the overmold transistor package is made of plastic. [21] The overmold transistor package of claim 14, wherein the transistor package is a monolithic integrated circuit. [22] The overmold transistor package of claim 14, wherein the transistor package is a hybrid integrated circuit. [23] The overmold transistor package of claim 14, wherein the overmold has a glass transition temperature greater than 135°C and a flexural modulus of less than 20 GPa. [24] The overmold transistor package of claim 23, wherein the overmold has a coefficient of thermal expansion of less than 50 ppm / °C at temperatures above the glass transition temperature and a coefficient of thermal expansion of less than 18 ppm / °C at temperatures below the glass transition temperature. [25] The overmold transistor package according to claim 24, wherein the overmold has a moisture absorption rate of less than 0.5%. [26] The transistor package according to one or more of claims 1-25, wherein the mold attachment material comprises sintered silver.

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