In order to construct various implantable microdevices, Dr. Sawan has proposed advanced mixed-signal (analog, digital & RF) circuits and systems addressing different specific needs and requirements. Most of these devices have been evaluated in vivo in collaboration with surgeons from specific domains. These research inventions are based on his innovative circuit techniques covering a range of building blocks in both voltage and current modes such as amplifiers, active filters, analog to digital (A/D) and D/A converters, a novel technique for offset cancellation in operational amplifiers, and a DC-free biphasic current source that is dedicated to miniaturized electrical stimulators. Besides these, his other contributions include a novel method to build linear power amplifiers, testing of advanced structures, digital and analog signal processing applications and microelectrode-to-tissue interfaces.

Dr. Sawan was the first to design, construct and package implantable selective micro-stimulators; to interconnect dies to a matrix of electrodes using flip-chip technology; to propose remote measurement techniques integrated in one chip; to propose a novel architecture for Frequency Lock-Loop; to achieve full-duplex data transmission of remotely powered devices; to propose on-chip integrated electroneurogram measurement techniques to evaluate the volume of the bladder; and to realize hand-held ultrasound echography devices intended for remote monitoring of internal body organs. He has also made pioneering contributions in modeling the effect of propagated energy during the electromagnetic link and its effects on tissues and to hearing aids. In addition, he built the first pressure sensor intended for application to respiration. Though all these projects span a variety of domains, the main focus has been on System on Chip (SoC) design and testing. Such SoC designs include analog, digital and RF circuits for wireless communication and signal and image processing. In these designs, special attention has been paid to optimizing energy consumption and surface occupancy without compromising reliability and flexibility. Dr. Sawan has offered tutorials and short courses at IEEE conferences and national/international research centers. Below are presented a few completed and upcoming research projects.

Main research projects

2009-… Data Networks and Smart Sensors for Safety-Critical Avionics Applications
High channel-count sensor and actuator devices are needed to tackle bulky wiring bundles introduced by the growing number of functions in aircraft. In new avionic systems, communications between devices across different application domains are needed, which drastically increases information flow within the aircraft. Wiring bundles and demand for a much higher communication bandwidth raise serious challenges requiring the development of new avionic data buses, smart sensors, and network interfaces.
In responding to these technological challenges, this project aims at developing a new avionic communication network allowing a reduction of the complexity of cabling by adopting a lower wire-count solution, using state-of-the-art avionic data network technologies. Digital interfaces will be developed to connect legacy position sensors and actuators to data buses. Emerging Microelectromechanical systems (MEMS) and photonic technologies will be employed to develop new lightweight, contactless, and reliable position sensors in order to provide enhanced performance while reducing the cost of deployment and maintenance. A multi-protocol/multi-rate architecture based on Avionics Full Duplex Switched Ethernet (AFDX) is chosen as the baseline network architecture, which would achieve a solution for avionics data networks combining throughput, architecture adaptability, and secure and safe digital data stream with reliable time determinism, bounded latency, guaranteed bandwidth, and fault tolerance suitable for safety-critical applications. This project will also address issues related to frequency selection and the effect of EMC and EMI for the development of safety-critical wireless communication systems of the future.
As we recognize the imperative to develop new avionics technologies and to contribute to the effort of the industrial partners to enhance their world-wide technological leadership position and market competitiveness, it can be expected that the successful completion of this project will not only provide a significant technological contribution, but also showcase the capabilities of Canadian industry and universities in the related sectors.

2008-… A portable wireless near-infrared spectroscopy system combined with electroencephalography for bedside monitoring of stroke and epileptic patients. Stroke and epilepsy are the two most common neurological problems. Near-infrared spectroscopy (NIRS), a novel technique which can non-invasively monitor the rapid changes of regional cerebral volume and tissue oxygenation (as seen during seizures or stroke), may be of great value in the understanding, evaluation and treatment of these conditions. Preliminary studies using relatively short NIRS recordings and a limited number of optodes have shown their clinical potential in distinct situations. Long-term NIRS monitoring, however, remains difficult with existing commercial devices being too bulky or too heavy for long-term measurements in epilepsy, stroke or intensive care units. Over the last few years, we have established a multidisciplinary collaborative task force to evaluate and develop dual imaging NIRS-videoEEG system for real-time monitoring. Building on work already started, we propose in this research program to develop an ultra-lightweight wireless combined multichannel NIRS-videoEEG long-term monitoring system. Once a prototype is completed, validation through pilot clinical studies exploiting its capacity for bedside long-term monitoring of both EEG and NIRS will be performed.

2007-… Wireless sensor platform dedicated to building smart medical devices. Design and implementation of microsystems dedicated to implantable sensor actuator networks is attracting many researchers. Such devices would allow for automatic monitoring and subsequent treatment or various medical conditions. These microsystems typically include an energy source, a dedicated processor and memory, data converters, several sensors, and an RF transceiver to communicate with a remote base-station. Implanting wireless networks in the human body could greatly help the medical research community in learning about the progression of some diseases, assess the response to treatment and proceed with treatment using either electrical stimulation or drug delivery. This proposal addresses strategic challenges related to such short-range sensor networks. The research will focus on building novel generic implantable sensing motes that will enable in situ acquisition, actuation and bidirectional transmission of commands or data. More specifically, this project concerns the implementation of a high efficiency power conversion chain, programmable step-down DC-DC converters, low-power agile RF frequency synthesizers, and low-power direct conversion RF transceivers. We expect that this research will significantly contribute to the fields of ultra-low power sensor telemetry systems suitable for long term implantable applications, of efficient techniques for communications between implanted sensors and a remote processing device, and of high-efficiency power conversion chains and management.

2007-… Intracortical Multiunit Implant to Create Vision for the Blind : Integration and validation. The number of legally blind Americans exceeds 1 million with around 10% of them having no perception of light whatsoever. This project is intended to answer the fundamental questions of creating vision for the blind using direct electrical stimulation for large scale visual prostheses. Several research groups have opted to design visual prostheses. Electrical stimulation of the retina or of the optic nerve can be used to reverse the loss of sight induced by outer retinal degeneration caused by diseases such as retinitis pigmentosa or even by age-related macular degeneration. These techniques, however, are not helpful in the case of diseases affecting the inner retina or whole thickness of the retina or the optic nerve, nor in the case of eye loss. Such diseases, nonetheless, can be reversed by using intracortical visual prostheses. Matrices of electrodes implanted in the visual cortex are used to create a visual image consisting of an array of visual perceptions, or phosphenes. The starting point of this proposed project is a well-established preliminary design which includes ASICs that have already been fabricated and tested on conventional electronic test benches. The ongoing work tackles four different and complementary facets of the problem, namely 1) Modeling, stimulation techniques and parameters, 2) implant implementation and optimization, including fabrication of electrode matrices and device encapsulation, 3) an external controller, including image acquisition and processing, and 4) in-vivo implantation in chronic animals and testing. We wish to provide sets of parameters for efficient, safe and effective chronic stimulation of the cortex. As the project involves actual implantation of devices, one important objective is to define reliable surgical techniques and optimal device physical characteristics and to acquire know-how regarding miniaturization and assembly. We also aim at maximizing the exploitation of the device by using advanced acquisition and processing techniques, which involve the design and integration of image sensors, processing algorithms and hardware on efficient and low power devices.

2006-… CMOS-Based Lab-On-Chip Design and Integration for future diagnostic tools. We are working toward the design and integration of Laboratory-On-Chip (LOC) structures. This technology is based on a novel electro-fluidic implementation and packaging procedures for blood-based diagnostics. An LOC-based diagnostic tool is a complex, hybrid system consisting of various electrical, fluidic, and biochemical components, connected electrically and through fluidic channels on a single platform. The microfluidic fabrication technique is based on a direct-write fabrication process (DWFP) while conventional wire bonding is needed for electrical connections. The microelectronic parts of proposed LOC put forward a high precision capacitive sensor carried out in in 0.18 um CMOS process. We were able to demonstrate the capability of the proposed DWFP to fabricate polymer-based microfluidics on top of CMOS chips for LOCs.

2006-… Innovative Design, Assembly and Packaging Facility for New Smart Medical Devices Microsystems. The complexity of Laboratory on Chip based microsystems calls for specialized infrastructure coupled with equipment dedicated to characterization. Hence, we now need equipment dedicated to building a new generation of smart medical devices. This equipment update is vital to attaining the processing precision required in advanced microsystems technologies. The resulting complete environments will allow the modeling of complex physical phenomena arising from the interaction between biological, electrochemical, electrical, microfluidic, microelectro-mechanical and optical structures. In addition, novel assembly and packaging methods have been developed to validate such hybrid systems of silicon chips integrated with microfluidics, optical structures and bioanalytical electrodes.

2005-… Microsystems dedicated to interface with the primary visual cortex: modelling and experimental validation. Integration of microelectronics in the medical domain is undergoing exponential acceleration. Many medical devices are being introduced that allow interaction with the nervous system through electronic interfaces. More than 20 applications exist that use such devices to treat Parkinson’s disease, epilepsy, and paralysis of members. Many researchers are devoting resources to this field of inquiry. In vision, the generation of images in a blind person is not based on simple principles, but must involve elaborate stimlation strategies. Convinced of the potential of electrical stimulation, we will carry out a rigorous investigation and will examine the decoding of information moving through the brain and its subsequent utilisation to recover organ functions from the cortex. This work requires a process of rigorous modelling, the design and implementation of electronic microsystems of great compexity, and biocompatible encapsulation. Next, experiments will be conducted on rats to validate the proposed model. The results will allow the creation of other medical devices and should facilitate the study of neurological phenomena. Finally, thanks to its innovative and multidisciplinary character, this project will attract high-achieving graduate students, establish a unique framework for developing strategic knowhow, and contribute to the training of highly qualified personnel to take on the competition in this promising niche.

2004-… Multichip-based structures dedicated to building microsystems for numerous applications. The latest microsystems design, implementation and packaging require advanced assembly infrastructure. Our team was granted by the Canadian Foundation for Innovation a high-performance custom assembly line made by Quad (now Tyco) for our needs. This unique facility in Canada is dedicated to producing hybrid circuits such as thin and thick film layer technologies, wafers, and various types and formats of printed circuit boards (PCBs) populated with various dedicated dies and other commercially available components such as SMTs, Flip-chips, etc. Most of these components come from different chip vendors or are designed in co-applicants’ laboratories, and are currently sent for fabrication in Asia, Europe and United States fabrication facilities. They are very small parts, and have to be reliable after packaging. These main constraints necessitate the use of high performance assembly methods and packaging techniques for their production. Our Custom Assembly Line includes equipment to operate as follows: Solder paste or epoxy can be applied on HC/PCB boards either by a screen printer with a stencil or by a dispensing needle. Utilizing sophisticated pattern recognition techniques, the core of the system then places at very high speed various components at specific locations on a board (die, wafers, hybrid circuits, PCB). The board is then shuttled to a reflow oven for curing the epoxy and soldering the parts. Many applications require the available Custom Assembly Line, such as wireless transceivers, smart medical devices (catheters, stimulators, and sensors), industrial controllers, etc. The present infrastructure will allow us to experiment with a variety of packaging techniques for a huge number of applications. The infrastructure will contribute to new stimulating job opportunities for our graduate students since they will now have access to state of the art technologies. This infrastructure will benefit the Canadian economy through job creation. Also, the health and well-being of Canadians will be enhanced with the introduction of several new medical devices.

2004-… Novel CMOS Analog-to-Digital Converters Dedicated to Wireless Receivers. There is an increasing research interest in building reconfigurable wireless devices dedicated to telecommunications as well as to medical devices. Such systems, built around software-defined radio, provide an efficient and comparatively inexpensive solution to the problem of building multimode, multi-band and multifunctional wireless devices that can be adapted, updated and enhanced using software upgrades. Eliminating the fixed hardware between the antenna and the digital processing unit is the main key in this scheme, which is accessible using a digitizing signal at radio frequencies. The creation of such flexible integrated devices requires high performance analog-to-digital converters (ADCs) to allow processing data in the digital domain, and then greatly improve upon the quality of wirelessely received information. In fact, ADCs and their corresponding preamplifiers, located in the front-end stage as close as possible to the receiving antenna, are the bottleneck of modern wireless receivers. In order to achieve the realization of the requested modules, we propose to design and test novel ADC topologies based on advanced blind calibration techniques and using latest CMOS submicron technology. Among the alternatives, we will explore the reconfigurable sigma-delta band-pass, the interleaved pipeline stages, and the flash structure. Also, special attention will be paid to construct a novel preamplification front-end to acquire very low amplitude signals. Such a front-end must remove undesired noise and convert resulting signals to digital high-voltage domain. The achievement of such complex devices will allow the involved researchers to acquire state-of-the-art knowledge, and offer the Canadian industries excellent technology transfer and hiring opportunities.

2003-… Wireless monitoring and subsequent selective stimulation to efficiently recover the bladder functions in spinal cord injured patients. Over the last few years, experimental work in both acute and chronic animals has been achieved either in our laboratory or elsewhere world-wide to avoid bladder-sphincter dyssynergia during voiding. Recently, we have conducted research on stimulation techniques on paraplegic dogs which involve selective stimulation of the sacral roots using high frequency blockade of the somatic fibers supplying the external sphincter with the simultaneous application of a low frequency current to stimulate the detrusor. This allowed us to achieve a low pressure complete voiding without having to cut the sacral posterior roots. Also, we have developed an implantable device built around two main microstimulators: to deliver selective stimulation and permanently stimulate the pelvic floor using low-frequency current in order to reduce (or eliminate) bladder hyperreflexia and to maintain bladder function. We focus the present research on the following specific objectives: 1) Design and construct a reliable measurement technique of bladder volume through the detection of the bladder afferent sensory nerve activity during the filling phase which will allow the patient to know when he has to empty. Different electroneurogram (ENG) measurement and processing techniques will be examined. Analog and signal processing methods will be applied in order to retrieve the expected data from noisy sensed weak amplitude signals; 2) Improve and test our recently developed “shape memory alloy” electrodes on chronic animals to evaluate their reliability and their possible induction of local reaction and nerve damage; 3) Build a new miniaturized multifunction measurement and stimulation system on one chip. This implant is intended to facilitate its implantation in man and to avoid or reduce the usual complaints of local reaction, pain or discomfort which are reported following implantation of existing relatively big devices.

2003-… RFIC techniques for efficient power transfer with full-duplex high data rate communication dedicated to electronic implants. Electronic devices operating inside the body to recover functions of human organs have generated a great deal of interest during the last two decades. Advances in microelectronics have led to the development of various miniaturized implantable artificial organs, sensors and electrical stimulators. These devices are intensively used in many disease circumstances: for example, cardiac pacemakers, cochlear implants, bladder controllers, cortical microstimulators, and functional neural systems which are dedicated to lower/upper extremity movements. Most of these devices are extra-corporally powered through RF transmitting energy systems. These systems are based on amplitude modulation transmission that rectifies a high-frequency carrier to power on the implant. In addition to the energy, inductive links allow transmitting bidirectional data. Available inductive links present low power efficiency due to the low coupling coefficient. It is even worse when more power is needed. Their data transmission modes are either unidirectional or half-duplex bidirectional that limit the controllability and the observability of the system. Also, the corresponding data rate transmission does not meet the needs of high speed applications. In addition, no any fully integrated interface is available, but discrete components are employed instead which results in devices with large dimensions and high power consumption. This project deals with the design and validation of RF integrated circuit (RFIC) based systems to efficiently interface implants with the outside world. The challenge is to integrate the electronic implant, the receiving power module and the communication interface in one chip and adequately integrate the external controller in another chip. Storage elements are also to be included within the same chip to make the implant autonomous. The transferred energy should be high enough in order to power up the whole implant. In addition, high data transfer rate (2 Mb/s) will be proposed and communication needs to be achieved without compromising power transfer and its efficiency.

2002-… Smart Medical Microsystems Dedicated for Wireless and Massively Parallel Neural Recording in the Cortex. The advent of microelectronics allowed the emergence of implantable sensors and stimulators and the interface of such microdevices to complex biological systems. However, the tools needed for the diagnosis of dysfunctions are still missing despite the significant progress in monitoring and recording instruments. In fact, no tool is available to measure the neural activity at deep cortical levels. Simultaneous recording of signals from a large group of cells located in specific areas of the cerebral cortex is becoming a necessity. Such measurements could help in understanding the behavior of the primary cortex and may allow physiological studies of the brain in order to address specific dysfunctions at the cortical as well as the deeper brain levels. Our research program aims to build fully implantable electronic microsystems grouping several arrays of microprobes. Each microprobe features embedded configurable mixed-signal circuitry for signal conditioning and site positioning mechanisms. This microprobe will be connected to a multielectrode array in order to allow direct interfacing to the brain for monitoring of extracellular biopotentials of neural cells. Such implantable microsystems incite us to find innovative multidisciplinary design and assembly solutions. The proposed devices will be wirelessly powered through the skin using inductive link techniques. That same RF link will also allow a communication channel to transmit multiplexed neural data from the implant and to acquire control parameters from an external controller. In order to satisfy the requirements of wirelessly powered electronic microdevices, RF system-on-chip (SoC) design approaches will be used. Special attention will be paid to building microdevices that work at ultra low-power levels. The resulting microsystems could be used for the long term in vivo recording of neural activity in the cerebral cortex and will allow us to improve the control of neural stimulators for numerous applications such as epilepsy, artificial vision, depression, schizophrenia.

2001-… Canadian Research Chair on Smart Medical Devices. This Chair is intended to create and test smart miniaturized medical devices, from design to in vivo testing. Its multidisciplinary activities span several fields of engineering and extend to more than 8 areas of medicine. Smart medical devices must be adapted to numerous patient changes and thus need to be easily reconfigurable and adjustable. A device of this nature comprises many important modules such as user interface, tissue interface, main controller, sensors, various actuators, etc. It necessitates the full design, experimental fabrication, laboratory testing, industry-type packaging, and, finally, experimental in vitro and vivo testing. Furthermore, the implantable device must undergo additional development steps to make it biocompatible and completely safe. It must be so designed as to provide an efficient radio frequency bidirectional link with an external controller. In addition, these devices often need to be miniaturized to the greatest possible extent, which requires close and sustained coordination of collaborating experts from both the medical and engineering fields.

2001-… Analog, digital and RF circuits and systems design. The research activities of the ReSMiQ are oriented toward advanced research in computer and system architectures, analog and mixed-signal circuit design, testing and verification, and applications such as telecommunications and biomedical devices. The ReSMiQ does work in these specific research domains in Quebec. It brings together the efforts of more than 20 researchers and 130 graduate students (master’s and Ph.D.) and professionals located in seven Quebec institutes; it is therefore one of the largest strategic research groups in Quebec and Canada. Our research activities span five major themes:
Computer and system architectures; Analog and mixed-signal circuit design; Analog, digital, and mixed-signal testing and verification; System-level design: modeling and synthesis, co-design and embedded systems; Applications in telecommunications, radio-frequency (RF) circuits, biomedical applications, optical interfaces, circuits and algorithms for signal and image processing.

2001-… High Voltage CMOS/DMOS circuits. This project encloses two main topics: Pre-characterization of HV devices from DALSA Semiconductor in order to determine optimal configurations as a function of application requirements. Factors such as output currents, slew-rates, tolerable duty-cycles and loads influence safe operating region and performances. Design of effective circuits using these technologies can greatly benefit from careful circuit optimization that is the purpose of this research. Optimal Design Access to DALSA Semiconductor High Voltage (HV) technologies. Also, ultrasound interface to scanners which necessitate HVMOS technologies as well as mixed-signal (analog/digital) circuits in order to build a new category of miniaturized hand-held monitoring devices. The emitter can be realized by using the HVMOS technology and will be integrated in the same chip as the receiver.

1998-… Wide-bandwidth analog to digital converters. This project concerns the design and realization of wide-bandwidth analog to digital converters (ADC) dedicated to wireless and ultrasound receivers. Two categories of ADCs have been built: 1) Nyquist frequency high speed ADC, and 2) Sigma-delta band-pass modulators. These ADCs are intended for communication systems. Also, low-power Sigma-Delta ADC dedicated to implantable electronic sensors is been developed. Low-voltage supply and voltage boosting technique are used to build such micropower circuit.
1996-… Modeling of neuromuscular activities. These modeling activities are dedicated for subsequent biomedical system design and implementation. Electromagnetic power transmission through the skin, interaction between ECG and EMG, Leg and arm movements are among the projects.

1995-… Ultrasonic monitoring system. The aims of this project are to develop a variety of ultrasonic systems. A simplified architecture was implemented to detect, a preset full-bladder threshold. Also, an ultrasound sectorial scanner receiver is bringing built. The integration of such device is motivated by the increasing need of hand-held medical equipment for numerous clinical applications. The echo receiver of such device includes logarithmic preamplifier, programmable amplifier and a fast analog to digital converter. Also, the device necessitates a wireless interface to display received images in a remote monitor and for bi-directional data transfer between the ultrasound generator and the receiver (transducer). The wireless interface is also dedicated to tagging (identification and security devices) and biomedical applications. These receivers includes: low noise amplifiers, mixers, phase shifters, AC-DC converters and regulators, high-speed phase-locked loop and frequency-locked loop (FLL), passive and active programmable filters as well as other circuits needed to demodulate Frequency and phase modulated signals.

1994-… Design of analog circuits. Several building blocks have been implemented for biomedical and telecommunications applications. The following high performance (high frequency and low-power) circuits are among the proposed modules: opamps, comparators, filters, etc. Transconductances, transimpedances, as well as various current mode and switched current elements have been designed and original structures were demonstrated. Also, several modules forming the implants were optimized in function of the surface occupancy of the circuit, the energy consumption and the linearity of the circuits.

1994-… Design of power amplifier controller. This work consists of an electronic circuit enabling the linearization of power amplifiers dedicated to telecommunications applications. Other modules for the same types of applications such as modulation, demodulation, phase-shifting, equalizing, etc, were also developed.

1992-94 Implementation of an optimized Kalman filter. This implementation consists of a parallel architecture of Kalman filter with unknown noise. The proposed approach is applied to a semi-systolic VLSI array to accelerate the matrix operations required in each iteration. A tri-trapezoidal array allows a matrix inversion in one clock cycle. This parallel implementation enables real time applications for predictions. Also, switched current circuit techniques were used to implement neural networks modeled by Matlab and used to compare the Widrow-Hoff LMS algorithm with an Adaline network based on a Kalman filter.

1993-98 Dedicated processor architectures. Several types of embedded processors were designed. These processors are intended to build dynamically reconfigurable Field Programmable Devices (FPDs). Particular interests were paid to design fast digital and mixed-signal (digital-analog) programmable devices intended for signal processing and other acceleration applications.

1993-96 Self-monitoring medicine dropper. This project concerns an electronic eyedrop monitor that stores the number of drops used along with relative timing information related to the cap opening moment.

1991-… Design, realization and testing of implantable sensors and actuators. Research activities on two large families of implantable devices are undertaken. The first is made up of a group of components dedicated to the control of the urinary system in paralyzed patients who have lost the two essential bladder functions (incontinence and retention). The second family involves a visual implant for blind patients. These pluridisciplinary projects include a wide variety of domains of interest in microelectronics and RF electronics. Important examples include the design of mixed-signal (analog-digital) dedicated integrated circuits, testability, wireless communication, signal and image processing, and programmable circuits. Special attention is required during the design phase of all these components in order to optimize energy consumption and area, while at the same time proposing systems that are very reliable and flexible.

1990-91 Urodynamic parameters measurement in dogs. This work required the construction of an implant consisting of 2 channels controlled by an external device and a PC based data acquisition front-end which is used to get the parameters. Analyses of such parameters lead to localize the micturation process.

1986-90 Design and realization of a transcutaneous neurological stimulator for bladder control in patients with spinal-cord injuries. The system includes: 1) an external controller based on a commercially available microcontroller which is used to send commands, clock and energy to the implant by inductive coupling techniques; 2) an implant that contains a full custom CMOS chip. This implant recuperates the transdermally received information and transmits it to the chip to extract the commands and use them to program and operate the multichannels stimulator. Also, a computerized transcutaneous neuromuscular stimulator has been developed to control the implantable urinary prosthesis. These devices were used for in-vivo experiments on paralyzed animals (dogs).

1987-88 Fertility detector. Design and realization of a CMOS-3 micron full-custom chip (11564 transistors). This chip contains RAM memory, timer and display decoder of a device for fertility detection.

1984-86 Computerized system to generate sound waves. Design and realization of a versatile computerized system to generate and control high level (140 dB) and long duration impulsive sound waves. The system is composed of a PC that commands a sound chain to simulate special transitory impulse-noise waveforms (spark generator, firearms, hammer and plate, etc.). This system was developed for hearing loss measurement in humans.

1984-85 Gate array multifunction chip. Design of an integrated circuit by CMOS 4 microns gate array technology. This is a multiproject chip that contains various basic logic circuit functions.

1983 Pulse-Code Modulation. Development of a Codec transceiver based on PCM integrated circuits.

© Mohamad Sawan 2011 / Last Update 14-11-2011