Ma Lin

Bio: Ma Lin is an academic researcher from Beijing Institute of Technology. The author has contributed to research in topics: Radiation pattern & Antenna measurement. The author has an hindex of 2, co-authored 2 publications receiving 14 citations.

A deductive method for antenna near-field computation in EMC prediction

Abstract: A method for the analysis of the near field of an antenna is presented; it can be used to deduce the parameters of the antenna near field by specific parameters of the far field. The deductive steps are: (1) deducing the discrete current distribution on the antenna aperture; (2) calculating the antenna near field. Some results are compared with given data, and the agreement is good. It can be widely used in assessment of the antenna near field.

A generalized algorithm for antenna near-field computation in EMC prediction

Abstract: A generalized method for analysis of antenna near field is presented which relies on both additivity of radiation field of discrete antenna elements and sampling method of an aperture field. It has advantages of implementing easily and saving the computing time and storage. Some results are compared with published data, and the agreement is good. It can be widely used in EMC prediction.

Design and analysis of an adaptive transcutaneous power telemetry for biomedical implants

Abstract: Inductively coupled coil pair is the most common way of wirelessly transferring power to medical implants. However, the coil displacements and/or loading changes may induce large fluctuations in transmitted power into the implant if no adaptive control is used. In such cases, it is required to transmit excessive power to accommodate all the working conditions, which substantially reduces the power efficiency and imposes potential safety concerns. We have implemented a power transfer system with adaptive control technique to eliminate the power variations due to the loading or coupling coefficient changes. A maximum of 250mW power is transmitted through an optimized coil pair driven by Class-E power amplifier. Load shift keying is implemented to wirelessly transfer data back from the secondary to primary side over the same coil pair, with data rate of 3.3 kbps and packet error rate less than 10/sup -5/. A pseudo pulsewidth modulation has been designed to facilitate back data transmission along with forward power transmission. Through this back telemetry the system transmits the information on received power, back from implant to primary side. According to the data received, the system adjusts the supply voltage of the Class-E power amplifier through a digitally controlled dc-dc converter, thus varying the power sent to the implant. The key system parameters are optimized to ensure the stability of the closed-loop system. Measurements show that the system can transmit the 'just-needed' power for a wide range of coil separation and/or loading conditions, with power efficiency doubled when compared to the uncompensated link.

A wideband frequency-shift keying wireless link for inductively powered biomedical implants

Abstract: A high data-rate frequency-shift keying (FSK) modulation protocol, a wideband inductive link, and three demodulator circuits have been developed with a data-rate-to-carrier-frequency ratio of up to 67%. The primary application of this novel FSK modulation/demodulation technique is to send data to inductively powered wireless biomedical implants at data rates in excess of 1 Mbps, using comparable carrier frequencies. This method can also be used in other applications such as radio-frequency identification tags and contactless smartcards by adding a back telemetry link. The inductive link utilizes a series-parallel inductive-capacitance tank combination on the transmitter side to provide more than 5 MHz of bandwidth. The demodulator circuits detect data bits by directly measuring the duration of each received FSK carrier cycle, as well as derive a constant frequency clock, which is used to sample the data bits. One of the demodulator circuits, digital FSK, occupies 0.29 mm/sup 2/ in the AMI 1.5-/spl mu/m, 2M/2P, standard CMOS process, and consumes 0.38 mW at 5 V. This circuit is simulated up to 4 Mbps, and experimentally tested up to 2.5 Mbps with a bit error rate of 10/sup -5/, while receiving a 5/10-MHz FSK carrier signal. It is also used in a wireless implantable neural microstimulation system.

A modular 32-site wireless neural stimulation microsystem

Abstract: This paper presents Interestim-2B, a modular 32-site wireless microstimulating ASIC for neural prosthesis applications, to alleviate disorders such as blindness, deafness, and severe epilepsy. Implanted just below the skull along with a high-density intracortical microelectrode array, the chip enables leadless operation of the resulting microsystem, accepting power and data through an inductive link from the outside world and inserting information into the nervous system in the form of stimulating currents. Each module contains eight current drivers, generating stimulus currents up to /spl plusmn/270 /spl mu/A with 5-b resolution, /spl sim/100M/spl Omega/ output impedance, and a dynamic range (headroom voltage) that extends within 150 mV of the 5 V supply rail, and 250 mV of the ground level. As many as 64 modules can be used in parallel, to drive multiprobe arrays of up to 2048 sites, with only a pair of connections to a common inductive-capacitive (LC) tank circuit, while receiving power (8.25 mW/module) and data (2.5 Mb/s) from a 5/10-MHz frequency shift keyed carrier. Every 4.6 mm /spl times/ 4.6 mm chip fabricated in a 1.5-/spl mu/m, 2M/2P standard CMOS process through MOSIS, houses two modules and generates up to 65 800 stimulus pulses/s.

A wideband frequency-shift keying demodulator for wireless neural stimulation microsystems

Abstract: This paper presents a wideband frequency-shift keying (FSK) demodulator which is suitable for a digital data transmission chain of wireless neural stimulation microsystems such as cochlear implants and retinal prostheses. The demodulator circuit derives a constant frequency clock directly from a FSK carrier, and uses this clock to sample the data bits. The circuit occupies 0.03 mm/sup 2/ in a 0.6 /spl mu/m, 2M/2P, standard CMOS process, and consumes 0.25mW at 5V. This demodulator circuit is experimentally tested at the transmission speed up to 2.5Mbps while receiving a 5/10 MHz FSK carrier signal in a cochlear implant system.