Joonhoi Hur

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Cognitive radio (CR) technology has been proposed as a promising solution for maximizing the utilization of already-crowded spectrum resources. As new algorithms, circuits and systems are developed for CR technology, it is essential to have a reconfigurable testbed system for their verification. A multistandard, fully software driven, cross-layer CR testbed(More)
This paper presents a 23 dBm fully digital transmitter designed in a standard 45 nm CMOS process. The digital transmitter replaces the entire analog/RF signal chain in a traditional transmitter architecture. It utilizes ΣΔ modulation and pulse-width modulation to turn high resolution baseband I and Q signals into switching signals, thereby(More)
This paper presents a 25 dBm outphasing power amplifier designed in a standard 45 nm CMOS process. Instead of using bulky quarter-wave transmission lines or transformers as non-isolated combiners, we propose a new combiner based on lump elements. The elements of the combiner act differently for in-phase and out-of-phase components, which allows additional(More)