I am Keisuke Kawahara, a Ph.D. student at Yokohama National University, Japan. My interests include integrated circuit design, silicon photonics, optical communication, microwave theory, and signal processing.
- April 2016 – March 2020: Bachelor of Electrical Engineering, Tokyo University of Science, Noda, Chiba, Japan
- April 2020 – March 2022: Master of Electrical Engineering, Tokyo University of Science, Noda, Chiba, Japan
- April 2022 – present: Ph.D. in Progress, Yokohama National University, Yokohama, Kanagawa, Japan
![Analog Multiplexer (AMUX)](https://private-user-images.githubusercontent.com/37934321/261212844-0a788fc4-a56a-4eec-8b89-ca3c76d87f3c.jpg?jwt=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.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.9CuRQ_I2599mDAEIoXTnzkChoX4LKSPO9oIDe8TJjoY)
The image-rejection analog multiplexer increases signal bandwidth threefold by combining digital signal processing with analog multiplication. (📑IEEE T-MTT) (📑IEEE RWS)
![Active Balun](https://private-user-images.githubusercontent.com/37934321/261214116-9ee94376-df53-490d-bfb3-57a3276ce3f3.jpg?jwt=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.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.07l_4HE0RcIvUYJ-Vt2A3n6PxjbZ4smsBxk2QEQY86s)
The active balun converts single-ended signals to differential signals while maintaining a compact design and minimal imbalance. (📑IEEE TCAS-I) (📑IEEE MWSCAS)
![Differential Distributed Amplifier](https://private-user-images.githubusercontent.com/37934321/261214517-aa5208c0-3d57-4b71-93ee-fc7e6e1efe1f.jpg?jwt=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.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.pF-ah2OzYIPy2KrfjFDk4DMAe9dQRnYjAegg3Nq_lks)
Coupled inductors reduce the area of the differential distributed amplifier by half and enable the amplification of differential signals at frequencies up to several tens of GHz. (📑IEICE TREL) (📑IEEE ISCAS)
![CMOS Temperature Sensor](https://private-user-images.githubusercontent.com/37934321/261533123-48220bc9-70ce-4559-a445-4366c4f87275.png?jwt=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.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.44b0P6jtaseClXMC655i_B4rGDUNeywlZVm_3FTVelE)
The trimless temperature sensor is based on an open-source design rule and is freely reusable. (GitHub Repository)
![CMOS Operational Amplifier](https://private-user-images.githubusercontent.com/37934321/261536324-bac48c37-9dc6-4ac8-a65d-e2768d07fd89.png?jwt=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.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.7idnilHHeLYRL7nUOoufhNqUcSlAckEx01IVNutwsuk)
The class-AB CMOS operational amplifier consumes only 7.7 µA and has a slew rate of 1 V/µs with a 1-nF load. (Slides for 2021 and 2020)