Ultra Low Power Low Voltage ASIC design and implementation
For a Novel Bone Conduction Implant (BCI) system
Sammanfattning: Patients who are suffering from conductive hearing loss, single sided deafness and mixedhearing loss, cannot be rehabilitated by conventional air conduction hearing aids due to thefunctionality losses in the middle ear. Since in these hearing impairments, the cochleafunctions perfectly, a bone conduction hearing aid is used for transmitting sound data to thecochlea. Today, percutaneous Bone Anchored Hearing Aid (BAHA) is an importantalternative for such individuals. These devices use a percutaneous snap coupling and boneanchored implant that incurs skin infections, requires a life-long commitment of care everyday, and there is a risk for implant damage due to trauma.
A novel Bone Conduction Implant (BCI) system is designed as an alternative to thepercutaneous system, because, it leaves the skin intact. The BCI system comprises digital andanalog signal processing units and applying amplitude modulation technique, soundinformation is transmitted to a permanently implanted transducer via an inductive link systemthrough the intact skin. A coupling insensitive efficient inductive power and data link isdesigned that can deliver maximum force output to the transducer.
The BCI system uses a 1.3 volt standard hearing aid battery that provides power to the entireelectronics and the transducer. In the process of designing and implementing the electronicsof the BCI, the most critical, challenging and interesting focus is to have a very highefficiency system. Using ultra low power low voltage electronics circuit design andimplementation with matured technologies, the power dissipation can be reduced and thewhole device will be high efficient and the battery lifetime will be increased. The poweramplifier design is another important part of the electronics that must be designed veryefficiently. The proposed high efficiency switching power amplifiers are Class-D and Class-E. Studying and designing an application-specific integrated circuit for BCI system thatcovers all the demands on the power and efficiency is the main goal of this project.
This Project has been divided into two different parts. In the first Part, Two differentprototypes which use Class-D and Class-E as their Power Amplifier have been designed andimplemented. The results proved Class-D amplifier as a better topology for this specificapplication with current consumption bellow 4mA which is significantly lower than 22mAwhich is consumed by Class-E for similar RF load. Spartan 3 board has been used as FPGAboard to produce Clock signal and Pulse-density-Modulation (PDM) to Pulse-Width-Modulation conversion.
In the second part, integrated version of proved circuit was designed in 0.35um StandardCMOS Technology and it was submitted for fabrication in SOIC 20 standard die frame.
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