Greensboro, NC, United States
Greensboro, NC, United States

RF Micro Devices , was an American company that designed and manufactured high-performance radio frequency systems and solutions for applications that drive wireless and broadband communications. Headquartered in Greensboro, North Carolina, RFMD traded on the NASDAQ under the symbol RFMD. The Company was founded in Greensboro, North Carolina, in 1991. RF Micro has 3500 employees, 1500 of them in Guilford County, North Carolina.The company's products, predominantly radio frequency integrated circuits and packaged modules that utilize them, were used in cellular networks and mobile phones, for wireless connectivity such as wireless LAN, GPS and Bluetooth, in cable modems and cable TV infastructure, and for other applications including military radar. The most important applications in terms of sales were GaAs-based power amplifiers and antenna control solutions used in mobile phones , WiFi RF front-ends and components used in wireless infrastructure equipment.The company announced in February 2014 that it would merge with TriQuint Semiconductor. On January 2nd, 2015, RFMD and Triquint jointly announced that they had completed their merger of equals to form Qorvo , and that Qorvo would start trading on the NASDAQ Global Stock Market starting from that day. Wikipedia.


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A method of fabricating a bonded wafer with low carrier lifetime in silicon comprises providing a silicon substrate having opposing top and bottom surfaces, modifying a top portion of the silicon substrate to reduce carrier lifetime in the top portion relative to the carrier lifetime in portions of the silicon substrate other than the top portion, bonding a piezoelectric layer having opposing top and bottom surfaces separated by a distance T over the top surface of the silicon substrate, and providing a pair of electrodes having fingers that are inter-digitally dispersed on a top surface of the piezoelectric layer, the electrodes comprising a portion of a Surface Acoustic Wave (SAW) device. The modifying and bonding steps may be performed in any order. The modified top portion of the silicon substrate prevents the creation of a parasitic conductance within that portion during operation of the SAW device.


Patent
RF Micro Devices | Date: 2016-04-28

Embodiments of radio frequency (RF) filtering circuitry are disclosed. In one embodiment, the RF filtering circuitry includes a first port, a second port, a first RF filter path, and a second RF filter path. The first RF filter path is connected between the first port and the second port and includes at least a pair of weakly coupled resonators. The weakly coupled resonators are configured such that a first transfer response between the first port and the second port defines a first passband. The second RF filter path is coupled to the first RF filter path and is configured such that the first transfer response between the first port and the second port defines a stopband adjacent to the first passband without substantially increasing ripple variation of the first passband defined by the first transfer response.


Patent
RF Micro Devices | Date: 2016-03-31

A bonded wafer with low carrier lifetime in silicon comprises a silicon substrate having opposing top and bottom surfaces, the structure of the silicon in a top portion of the silicon substrate having been modified to reduce the carrier lifetime in the top portion relative to the carrier lifetime in portions of the silicon substrate other than the top portion; a piezoelectric layer bonded over the top surface of the silicon substrate and having opposing top and bottom surfaces separated by a distance T; and a pair of electrodes having fingers that are inter-digitally dispersed on the top surface of the piezoelectric layer in a pattern having a center-to-center distance D between adjacent fingers of the same electrode, the electrodes comprising a portion of a Surface Acoustic Wave (SAW) device. Modification of the top portion of the silicon substrate prevents the creation of a parasitic conductance within the top portion of the silicon substrate during operation of the SAW device.


Stealth-dicing-compatible devices and methods to prevent acoustic backside reflections on acoustic wave devices are disclosed. An acoustic wave device comprises a substrate having opposing top and bottom surfaces, where a first portion of the bottom surface has a higher roughness than a second portion of the bottom surface, and an acoustic resonator over the top surface of the substrate. The acoustic resonator comprises a piezoelectric layer having opposing top and bottom surfaces and a plurality of electrodes, at least some of which are disposed on the top surface of the piezoelectric layer. The first portion of the bottom surface of the substrate is below and opposite from the acoustic resonator, and the second portion of the bottom surface of the substrate is not located below and opposite from the acoustic resonator. Multiple first portions, each separated from the other by second portions, may exist.


A method of making a capacitor with reduced variance comprises providing a bottom plate in a first metal layer, a first dielectric material over the bottom plate, and a middle plate in a second metal layer to form a first capacitor. The method also comprises measuring the capacitance of the first capacitor, and determining whether to couple none, one, or both of a second capacitor and a third capacitor in parallel with the first capacitor. The method may further comprise the steps of providing a second dielectric material over the middle plate, and providing a first top plate and a second top plate in a third metal layer to form the second capacitor, and a third capacitor. Electrical connections may be formed to couple one or both of the second capacitor and the third capacitor in parallel with the first capacitor based on the measured value of the first capacitor.


Patent
RF Micro Devices | Date: 2015-11-30

Embodiments of a Surface Acoustic Wave (SAW) device, or filter, and methods of fabrication thereof are disclosed. In some embodiments, the SAW filter comprises a piezoelectric substrate and an Interdigitated Transducer (IDT) on a surface of the piezoelectric substrate. The IDT includes multiple fingers, each comprising a metal stack. The SAW filter further includes a cap layer on a surface of the IDT opposite the piezoelectric substrate and on areas of the surface of the piezoelectric substrate exposed by the IDT. The cap layer has a thickness in a range of and including 10 to 500 Angstroms and a high electrical resistivity (and thus a low electrical conductivity). For instance, in some embodiments, the electrical resistivity of the cap layer is greater than 10 kilo-ohm meters (Km). The SAW filter further includes an oxide overcoat layer on a surface of the cap layer opposite the IDT and the piezoelectric substrate.


The present disclosure relates to antenna swapping for a wireless, e.g., cellular, radio system. In particular, embodiments of a single-die antenna swapping switching circuit are disclosed. In some embodiments, the single-die antenna swapping switching circuit enables antenna swapping in a wireless device using only two coaxial cables or transmission line connections regardless of an order of an antenna multiplexer of the wireless device. This results in significant space savings, particularly as the order of the antenna multiplexer increases, compared to antenna swapping techniques that require a pair of coaxial cables or transmission lines for each order of the antenna multiplexer. In addition, the single-die antenna swapping switching circuit is designed to be located between a radio front-end system and the antenna multiplexer such that intermodulation distortion and harmonics resulting from the switches comprised in the single-die antenna swapping switching circuit are mitigated.


The present disclosure relates to a silicon-on-insulator (SOI) substrate structure with a buried dielectric layer for radio frequency (RF) complementary metal-oxide semiconductor (CMOS) switch fabrications. The buried dielectric layer suppresses back-gate transistors in the RF CMOS switches fabricated on the SOI substrate structure. The SOI substrate structure includes a silicon handle layer, a silicon oxide layer over the silicon handle layer, a buried dielectric layer over the silicon oxide layer, and a silicon epitaxy layer directly over the buried dielectric layer.


Patent
RF Micro Devices | Date: 2016-04-20

The present disclosure relates to a multi-layer substrate structure with an embedded die to miniaturize designs and improve performance. The multi-layer substrate structure includes a core layer having a cavity and a die mounted within the cavity. The die has a die body, a die conductive element on a top surface of the die body, and a dielectric layer over the die conductive element. The multi-layer substrate structure also includes a substrate conductive element formed over a portion of a top surface of the core layer and extending over at least a portion of the die conductive element. Overlapping portions of the die conductive element and the substrate conductive element are separated by the dielectric layer and form an electronic component.


Patent
RF Micro Devices | Date: 2016-04-18

A front-end module configured to cancel unwanted transmit spectrum at one or more receivers comprises at least one transmitter having a power amplifier and configured to transmit signals to an antenna. The front-end module also comprises at least one receiver to receive the transmit signals, wherein the at least one receiver receives at least a portion of unwanted transmit spectrum. A directional coupler couples at least a portion of a transmit output signal from the power amplifier to provide a coupled transmit output signal to signal conditioning circuitry associated with the at least one receiver and configured to condition the coupled transmit output signal to generate a conditioned transmit signal to provide to the at least one receiver, wherein the conditioned transmit signal at least partially cancels the unwanted transmit spectrum. The signal conditioning circuitry may adjust the amplitude and phase of the coupled transmit output signal.

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