#### Filter Results:

- Full text PDF available (17)

#### Publication Year

1988

2017

- This year (2)
- Last 5 years (29)
- Last 10 years (52)

#### Publication Type

#### Co-author

#### Journals and Conferences

#### Key Phrases

Learn More

- Dongsu Kim, Jiang Zeng
- J. Comb. Theory, Ser. A
- 2001

We give a new decomposition of derangements, which gives a direct interpretation of a formula for their generating function. This decomposition also works for counting derangements by number of excedances.

- Dongsu Kim, Daehyun Kang, Jinsung Choi, Jooseung Kim, Yunsung Cho, Bumman Kim
- IEEE Transactions on Microwave Theory and…
- 2011

This paper describes the analysis of an optimized envelope shaping function for the envelope tracking power amplifier (ET PA) and its implementation. The proposed shaping function, which is sweet spot tracking with crest factor reduction, improves the efficiency and output power of the power amplifier (PA), as well as its linearity. For an accurate… (More)

- Daehyun Kang, Dongsu Kim, Yunsung Cho, Byungjoon Park, Jooseung Kim, Bumman Kim
- IEEE Transactions on Microwave Theory and…
- 2011

A quarter-wavelength impedance transformer as well as a number of other factors limit the bandwidth (BW) of Doherty power amplifiers (PAs). We utilize the lower Q of a quarter-wave length transformer and propose a phase compensation circuit and an additional offset line to be incorporated into the matching net works for an enhanced BW of the Doherty PA. The… (More)

- Jinsung Choi, Dongsu Kim, Daehyun Kang, Bumman Kim
- IEEE Transactions on Microwave Theory and…
- 2009

This paper presents the realization of a linear polar transmitter supporting multistandard applications. The harmonic-tuned class-AB biased (class-AB/F) power amplifier (PA) with the novel envelope shaping method linearly amplifies the input signal with high efficiency. The hybrid switching supply modulator with programmable hysteretic comparator enables… (More)

- Jinsung Choi, Jounghyun Yim, +5 authors Bumman Kim
- IEEE Transactions on Microwave Theory and…
- 2007

This paper demonstrates a new polar transmitter architecture, which uses the digitized envelope signal to control the drain voltage of a switching mode power amplifier (PA). It is based on a novel polar modulation using the constant envelope modulated signal. Among the various constant envelope modulators, the DeltaSigma modulator is chosen for its… (More)

- Daehyun Kang, Byungjoon Park, Dongsu Kim, Jooseung Kim, Yunsung Cho, Bumman Kim
- IEEE Transactions on Microwave Theory and…
- 2013

An envelope-tracking (ET) CMOS power amplifier (PA) is fabricated using a 0.18- μm CMOS process. The module containing the supply modulator, the PA, and the output transformer is implemented on a printed circuit board (PCB). The CMOS PA employs the second and third harmonic controls at the input and the second harmonic short at the output for… (More)

- Jun-Chul Park, Jong-Gwan Yook, +5 authors Chan-Sei Yoo
- IEEE Transactions on Microwave Theory and…
- 2013

This paper presents a gallium nitride (GaN)-based hybrid current-mode class-S (CMCS) power amplifier (PA) using a bandpass delta-sigma modulator (BPDSM) for a 955-MHz LTE signal. To enhance the drain efficiency of the CMCS PA, the chip-on-board (COB) technique, which can reduce the external parasitic components of the packaged transistor and allow fast… (More)

- Jooseung Kim, Dongsu Kim, Yunsung Cho, Daehyun Kang, Byungjoon Park, Bumman Kim
- IEEE Transactions on Microwave Theory and…
- 2013

This paper presents an envelope tracking power amplifier (ET PA) using a dual-mode supply modulator for handset application. The supply modulator has a combined structure with a linear amplifier and a switching amplifier. The dual-mode supply modulator operates in high-power mode and low-power mode by providing the supply voltage of the linear amplifier of… (More)

- Dongsu Kim, Jinsung Choi, Daehyun Kang, Bumman Kim
- 2010 IEEE Radio Frequency Integrated Circuits…
- 2010

This paper describes the implementation of a high efficiency and wideband envelope tracking power amplifier with sweet spot tracking. By modulating supply voltage of power amplifier (PA), efficiency can be increased significantly. And linearity is improved by envelope shaping and sweet spot tracking. The supply modulator has a combined structure of a… (More)

- Hadong Jin, Dongsu Kim, Bumman Kim
- J. Solid-State Circuits
- 2017

In this paper, we proposed and designed a digitally configured versatile RF quadrature transmitter. The transmitter efficiency was enhanced by IQ cell sharing and the deactivation of cells of opposite phases. In simulation, these techniques were able to increase the average efficiency of the transmitter from 46.3% to 70.7% for a 6.9-dB PAPR LTE signal.… (More)