1 V CMOS subthreshold log domain PDM

A new CMOS circuit strategy for very low-voltage Pulse-Duration Modulators (PDM) is proposed. Optimization of voltage supply scaling below the sum of threshold voltages is based on Instantaneous Log Companding processing through the MOSFET operating in weak inversion. A 1 V VLSI PDM circuit for very low-voltage audio applications such as Hearing Aids is presented, showing good agreement between simulated and experimental data.Comisión Interministerial de Ciencia y Tecnología TIC97-1159, TIC99-1084European Union 2306

The development of the audio-visual voice comparator for speech and hearing therapy

Thesis (Ed.M.)--Boston Universit

Inverter-Based Low-Voltage CCII- Design and Its Filter Application

This paper presents a negative type second-generation current conveyor (CCII-). It is based on an inverter-based low-voltage error amplifier, and a negative current mirror. The CCII- could be operated in a very low supply voltage such as ±0.5V. The proposed CCII- has wide input voltage range (±0.24V), wide output voltage (±0.24V) and wide output current range (±24mA). The proposed CCII- has no on-chip capacitors, so it can be designed with standard CMOS digital processes. Moreover, the architecture of the proposed circuit without cascoded MOSFET transistors is easily designed and suitable for low-voltage operation. The proposed CCII- has been fabricated in TSMC 0.18μm CMOS processes and it occupies 1189.91 x 1178.43μm2 (include PADs). It can also be validated by low voltage CCII filters

Analysis and Design of RF Power and Data Link Using Amplitude Modulation of Class-E for a Novel Bone Conduction Implant

This paper presents analysis and design of a radio frequency power and data link for a novel Bone Conduction Implant (BCI) system. Patients with conductive and mixed hearing loss and single-sided deafness can be rehabilitated by bone-anchored hearing aids (BAHA). Whereas the conventional hearing aids transmit sound to the tympanic membrane via air conduction, the BAHA transmits sound via vibrations through the skull directly to the cochlea. It uses a titanium screw that penetrates the skin and needs life-long daily care; it may cause skin infection and redness. The BCI is developed as an alternative to the percutaneous BAHA since it leaves the skin intact. The BCI comprises an external audio processor with a transmitter coil and an implanted unit called the bridging bone conductor with a receiver coil. Using amplitude modulation of the Class-E power amplifier that drives the inductive link, the sound signal is transmitted to the implant through the intact skin. It was found that the BCI can generate enough output force level for candidate patients. Maximum power output of the BCI was designed to occur at 5-mm skin thickness and the variability was within 1.5 dB for 1–8-mm skin thickness variations

Amplificador classe D CMOS para aparelho de auxílio à audição

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2010O presente trabalho propõe um amplificador classe D operando com baixa tensão e com consumo reduzido para aplicações em aparelhos de auxílio à audição. Projetado em modo corrente, explora as técnicas de compressão (log companding) e multiplicação (translinear loop). O sistema foi projeta-do de forma modular, estudando o desempenho de cada bloco, com ênfase no consumo de potência. Foram extraídos os parâmetros tecnológicos mais significativos do modelo do transistor MOS para diferentes tamanhos de transistores, realizando um projeto baseado em associações série-paralelo. Analisamos a influência dos filtros da saída no consumo, considerando a característica indutiva que apresentam os alto-falantes. O funcionamento do sistema foi verificado através de simulações do circuito projetado em tecno-logia AMS 0.35 ?m. Verificassem eficiência superior a 75% para potência na saída maior que um quarto da potência máxima, obtendo uma eficiência máxima de 90,6%, um consumo estático de 68 ?W, distorção harmônica inferior a 1%, sendo a área ativa de silício de 0,073mm2.This work proposes a class-D amplifier for low voltage operation and reduced consumption, for application in hearing aid devices. Designed in current mode, the amplifier employs log companding for compression and multiplication techniques. The performance of each block of the amplifier was analyzed, and special emphasis was given to power consumption. The most significant technological parameters of the MOSFET model were extracted for different transistor sizes. The design of the amplifier is based on the series-parallel associations of transistors. We analyze the influence of the output filters on the power consumption, considering the speaker's inductive characteristic. The correct operation of the system was verified through simulations of the circuits designed in the AMS 0.35 ?m technology. Efficiencies over 75%, up to a maximum of 90.6 % were achieved for output power greater than one quarter of the maximum power. The static power consumption is 68 ?W, with total harmonic distortion less than 1%. The amplifier active area is around 0.073 mm2

Southwest Research Institute assistance to NASA in biomedical areas of the technology utilization program

The activities are reported of the NASA Biomedical Applications Team at Southwest Research Institute between 25 August, 1972 and 15 November, 1973. The program background and methodology are discussed along with the technology applications, and biomedical community impacts

The Impact of Different Levels of Instruction on the Outcomes of Using a Personal Sound Amplifier Product

Personal sound amplifiers (PSAPs) provide accessible and affordable healthcare to hearing impaired individuals that would otherwise not seek treatment. Like a self-fitting hearing aid, PSAPs do not involve an audiology service. The current pilot study investigated the impact different levels of instruction have on the effectiveness of using a personal sound amplifier product for four participants with mild to moderate sensorineural hearing loss. Basic written instruction and premium audiology services were utilized to teach participants how to use the device. Preliminary data suggested that the acquired knowledge, skills, and outcomes of using the PSAPs were similar between two levels of services after 6 weeks of use

A case study of interventions to facilitate learning for pupils with hearing impairment in Tanzania

Background: Hearing is essential for learning in school, and untreated hearing loss may hinder quality education and equal opportunities. Detection of children with hearing loss is the first step in improving the learning situation, but effective interventions must also be provided. Hearing aids can provide great benefit for children with hearing impairment, but this may not be a realistic alternative in many low- and middle-income countries because of the shortage of hearing aids and hearing care service providers. Objective: In this study, alternative solutions were tested to investigate the potential to improve the learning situation for children with hearing impairment. Method: Two technical solutions (a personal amplifier with and without remote microphone) were tested, in addition to an approach where the children with hearing impairment were moved closer to the teacher. A Swahili speech-in-noise test was developed and used to assess the effect of the interventions. Results: The personal sound amplifier with wireless transmission of sound from the teacher to the child gave the best results in the speech-in-noise test. The amplifier with directive microphone had limited effect and was outperformed by the intervention where the child was moved closer to the teacher. Conclusion: This study, although small in sample size, showed that personal amplification with directive microphones did little to assist children with hearing impairment. It also indicated that simple actions can be used to improve the learning situation for children with hearing impairment but that the context (e.g. room acoustical parameters) must be taken into account when implementing interventions. Contribution: The study gives insight into how to improve the learning situation for school children with hearing impairment and raises concerns about some of the known technical solutions currently being used.publishedVersio

Affordable Frequency Selective Hearing Amplifier

One of the most prevalent diseases affecting human communication is hearing loss. About one in every six people has a hearing deficit globally. Many people suffer from hearing loss but cannot afford a hearing aid because of the high cost set by manufacturers. In this study, we aim to design a frequency-selective hearing amplifier that could be used as an alternative to hearing aids by having an external controller and separate earpieces. The controller allows the user to select the correct frequency bands to be amplified according to the listeners’ degree of hearing loss. As a starting point, we have divided the frequency range of hearing into three bands: 125 Hz to 1 kHz, 1 Hz to 4 kHz, and 4 Hz to 8 kHz. The microphone picks up the signal, and the Analog-to-Digital Converter (ADC) converts the signal to digital form which then goes through a microcontroller where filtering and amplification take place. The amplified frequency band of the signal is then added to the rest of the signal and rescaled before a Digital-to-Analog Converter (DAC) converts the signal to an analog form. Analog signals would go through a second amplifier to adjust the overall speech level that can be heard via the earpiece. The circuit components in the amplifier could be adjusted to produce the desired amount of amplification. The proposed design is tested thoroughly to ensure that a wide range of amplification is achieved for a wide range of listeners with various degrees of hearing loss