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An Integrated Circuit for Biphasic Pulse Generator with Variable Parameters
Shinyong Shim,Jaehoon Sung,Sung June Kim 대한전자공학회 2021 Journal of semiconductor technology and science Vol.21 No.4
A biphasic pulse generator integrated circuit (IC) was designed, and the parameters of the generated pulses such as pulse rate, duration, and amplitude were adjusted to the desired values by using the time-varying differences of two inputs of the operational amplifier integrated on the IC. The chip was fabricated with the MagnaChip /SK Hynix CMOS 0.35 ㎛ process, which allowed a maximum pulse amplitude of 3.3 V. In addition, it included a transformer that allowed the IC to rectify the amplitude modulated (AM) input with a 1 ㎓ carrier and provide the supply voltage to generate the pulses. The whole size of the full system was 441.5 ㎛×527.8 ㎛, and the system successfully generates biphasic pulses up to 1.2 ㎑ using the RF signal. This circuit can be used to generate biphasic pulses with variable parameters for distributed neural interfaces, and to provide scan voltages for potentiostat applications such as in the Fast Scan Cyclic Voltammetry (FSCV). In addition, this IC with an integrated transformer suggests that a wireless electroanalytical system on a chip can be achieved as a future work.
FPGA 기반 64채널 다중 주파수 제어가 가능한 초음파 펄서 시스템
전호윤(Hoyoon Jeon),심신용(Shinyong Shim),이현수(Hyun-Su Lee),김태룡(Tae Ryong Kim),이형민(Hyung-Min Lee),김진식(Jinsik Kim),이병철(Byung Chul Lee) 대한전자공학회 2020 대한전자공학회 학술대회 Vol.2020 No.11
This study aimed to enhance a 64-channel ultrasonic pulser system’s performance by controlling frequency in each channel. Conventional systems are integrated as one body and operate pulse generation at one preset frequency, limiting the effectiveness of ultrasonic applications. A 64-channel FPGA was implemented to our ultrasonic pulser system to increase system capability with various frequencies. Additionally, detachable circuit boards were designed for a modularized system to enable selective replacement and improvement of modularized circuits. Several variables such as frequency, PRF, cycle, and time delay for each channel were measured by an oscilloscope to be identical to preset values; therefore, the system operation was verified successfully. The suggested FPGA-based 64-channel ultrasonic pulser system can be used primarily for ultrasound-guided ultrasound therapy with various transducers in the future.
Jeong Hoan Park,Shinyong Shim,Joonsoo Jeong,Sung June Kim 대한전자공학회 2017 Journal of semiconductor technology and science Vol.17 No.1
We propose a novel multi-photodiode array (MPDA) based retinal implant IC with on/off stimulation strategy for a visual prosthesis with improved spatial resolution. An active pixel sensor combined with a comparator enables generation of biphasic current pulses when light intensity meets a threshold condition. The threshold is tuned by changing the discharging time of the active pixel sensor for various light intensity environments. A prototype of the 30-channel retinal implant IC was fabricated with a unit pixel area of 0.021㎟, and the stimulus level up to 354 μA was measured with the threshold ranging from 400 lx to 13120 lx.
Park, Jeong Hoan,Shim, Shinyong,Jeong, Joonsoo,Kim, Sung June The Institute of Electronics and Information Engin 2017 Journal of semiconductor technology and science Vol.17 No.1
We propose a novel multi-photodiode array (MPDA) based retinal implant IC with on/off stimulation strategy for a visual prosthesis with improved spatial resolution. An active pixel sensor combined with a comparator enables generation of biphasic current pulses when light intensity meets a threshold condition. The threshold is tuned by changing the discharging time of the active pixel sensor for various light intensity environments. A prototype of the 30-channel retinal implant IC was fabricated with a unit pixel area of $0.021mm^2$, and the stimulus level up to $354{\mu}A$ was measured with the threshold ranging from 400 lx to 13120 lx.