Ki Joong Kim

TL;DR: In this article, a dual-band directional coupler with strip lines for signal coupling and inter-digital capacitors for phase compensation is described, which is implemented with a single-input single-out (SISO) and dual-output (DISO) transmitter.

TL;DR: A power amplifier system with power control function provides accurate and efficient power control by controlling a bias voltage and a bias current of the power amplifier at the same time as discussed by the authors, and a voltage detection controller detecting the magnitude of the bias voltage being supplied to the power amplifier and comparing the magnitude with a predetermined reference voltage.

TL;DR: In this paper, a driver amplifier control may be provided in conjunction with power amplifier control to improve the power efficiency and/or dynamic range of the transmitter system, which may lessen the burden of digital to analog converters (DACs) in transmitter systems such as cellular transmitter systems.

TL;DR: In this paper, an integrated passive device (IPD) is used to interconnect the signal amplification and power combining sections of a power amplifier, which may have characteristics of high performance passive devices with flexibility of implementing diverse functions, including a notch filter, a low pass filter, and bypass capacitance for bias network.

TL;DR: In this paper, a bias circuit providing different bias voltages depending on a power mode through a simple circuit, and a power amplifier having the same voltage levels are provided, and the bias circuit and the power amplifier include a bias setting unit configured to vary a voltage level of a control signal controlling a bias voltage according to an operation of a first transistor being switched-off in a high power mode and switched-on in a low power mode.