Matching Items (3)
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- All Subjects: Microelectromechanical Systems
- Creators: Aberle, James T., 1961-
Description
A dual-channel directional digital hearing aid (DHA) front-end using a fully differential difference amplifier (FDDA) based Microphone interface circuit (MIC) for a capacitive Micro Electro Mechanical Systems (MEMS) microphones and an adaptive-power analog font end (AFE) is presented. The Microphone interface circuit based on FDDA converts the capacitance variations into voltage signal, achieves a noise of 32 dB SPL (sound pressure level) and an SNR of 72 dB, additionally it also performs single to differential conversion allowing for fully differential analog signal chain. The analog front-end consists of 40dB VGA and a power scalable continuous time sigma delta ADC, with 68dB SNR dissipating 67u¬W from a 1.2V supply. The ADC implements a self calibrating feedback DAC, for calibrating the 2nd order non-linearity. The VGA and power scalable ADC is fabricated on 0.25 um CMOS TSMC process. The dual channels of the DHA are precisely matched and achieve about 0.5dB gain mismatch, resulting in greater than 5dB directivity index. This will enable a highly integrated and low power DHA
ContributorsNaqvi, Syed Roomi (Author) / Kiaei, Sayfe (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Chae, Junseok (Committee member) / Barnby, Hugh (Committee member) / Aberle, James T., 1961- (Committee member) / Arizona State University (Publisher)
Created2011
Description
The high cut-off frequency of deep sub-micron CMOS technologies has enabled the integration of radio frequency (RF) transceivers with digital circuits. However, the challenging point is the integration of RF power amplifiers, mainly due to the low breakdown voltage of CMOS transistors. Silicon-on-insulator (SOI) metal semiconductor field effect transistors (MESFETs) have been introduced to remedy the limited headroom concern in CMOS technologies. The MESFETs presented in this thesis have been fabricated on different SOI-CMOS processes without making any change to the standard fabrication steps and offer 2-30 times higher breakdown voltage than the MOSFETs on the same process. This thesis explains the design steps of high efficiency and wideband RF transmitters using the proposed SOI-CMOS compatible MESFETs. This task involves DC and RF characterization of MESFET devices, along with providing a compact Spice model for simulation purposes. This thesis presents the design of several SOI-MESFET RF power amplifiers operating at 433, 900 and 1800 MHz with ~40% bandwidth. Measurement results show a peak power added efficiency (PAE) of 55% and a peak output power of 22.5 dBm. The RF-PAs were designed to operate in Class-AB mode to minimize the linearity degradation. Class-AB power amplifiers lead to poor power added efficiency, especially when fed with signals with high peak to average power ratio (PAPR) such as wideband code division multiple access (W-CDMA). Polar transmitters have been introduced to improve the efficiency of RF-PAs at backed-off powers. A MESFET based envelope tracking (ET) polar transmitter was designed and measured. A low drop-out voltage regulator (LDO) was used as the supply modulator of this polar transmitter. MESFETs are depletion mode devices; therefore, they can be configured in a source follower configuration to have better stability and higher bandwidth that MOSFET based LDOs. Measurement results show 350 MHz bandwidth while driving a 10 pF capacitive load. A novel polar transmitter is introduced in this thesis to alleviate some of the limitations associated with polar transmitters. The proposed architecture uses the backgate terminal of a partially depleted transistor on SOI process, which relaxes the bandwidth and efficiency requirements of the envelope amplifier in a polar transmitter. The measurement results of the proposed transmitter demonstrate more than three times PAE improvement at 6-dB backed-off output power, compared to the traditional RF transmitters.
ContributorsGhajar, Mohammad Reza (Author) / Thornton, Trevor (Thesis advisor) / Aberle, James T., 1961- (Committee member) / Bakkaloglu, Bertan (Committee member) / Goryll, Michael (Committee member) / Arizona State University (Publisher)
Created2012
Description
ABSTRACT
Designers creating the next generation remote sensing enabled smart devices need to overcome the challenges of prevailing ventures including time to market and expense.
To reduce the time and effort involved in initial prototyping, a good reference design is often desired and warranted. This paper provides the necessary reference materials for Designers to implement a wireless solution efficiently and effectively.
This document is intended for users with limited Bluetooth technology experience.
Many sensing-enabled devices require a ‘hard-wire’ or cable link to a host monitoring system. This can limit the potential for product advancements by anchoring the system to a single location preventing portability and the convenience of a remote system. By removing the “wired” or cabled portion from a design, a broader scope of devices becomes feasible.
One common problematic area for these types of sensors is within the internal medicine field. Proximity sensing is far more practical and less invasive to implement than surgical implantation. Bluetooth Low Energy (BLE) systems solve the hard wired problem by decoupling the physical sensor from the host system through a BLE transceiver that can send information to an external monitoring system. This wireless link enables new sensor technology to be leveraged into previously unobtainable markets; such as, internal medicine, wearable devices, and Infotainment to name a few. Wireless technology for sensor systems are a potentially disruptive technology changing the way environmental monitoring is implemented and considered.
With this BLE design reference, products can be created with new capabilities to advance current technologies for military, commercial, industrial and medical sectors in rapid succession.
Designers creating the next generation remote sensing enabled smart devices need to overcome the challenges of prevailing ventures including time to market and expense.
To reduce the time and effort involved in initial prototyping, a good reference design is often desired and warranted. This paper provides the necessary reference materials for Designers to implement a wireless solution efficiently and effectively.
This document is intended for users with limited Bluetooth technology experience.
Many sensing-enabled devices require a ‘hard-wire’ or cable link to a host monitoring system. This can limit the potential for product advancements by anchoring the system to a single location preventing portability and the convenience of a remote system. By removing the “wired” or cabled portion from a design, a broader scope of devices becomes feasible.
One common problematic area for these types of sensors is within the internal medicine field. Proximity sensing is far more practical and less invasive to implement than surgical implantation. Bluetooth Low Energy (BLE) systems solve the hard wired problem by decoupling the physical sensor from the host system through a BLE transceiver that can send information to an external monitoring system. This wireless link enables new sensor technology to be leveraged into previously unobtainable markets; such as, internal medicine, wearable devices, and Infotainment to name a few. Wireless technology for sensor systems are a potentially disruptive technology changing the way environmental monitoring is implemented and considered.
With this BLE design reference, products can be created with new capabilities to advance current technologies for military, commercial, industrial and medical sectors in rapid succession.
ContributorsHughes, Clinton Francis (Author) / Blain Christen, Jennifer (Thesis advisor) / Ozev, Sule (Committee member) / Ogras, Umit Y. (Committee member) / Aberle, James T., 1961- (Committee member) / Arizona State University (Publisher)
Created2015