Seong-Min Oh

A new DGS unequal power divider

An unequal Wilkinson power divider having rectangular-shaped defected ground structure (DGS) is proposed. DGS microstrip line adopted for the divider is composed of double-layer substrate which removes the ground problem of the previous DGS structures in packaging. The first layer includes DGS on the bottom ground plane. The second substrate of which top metal plane has been removed is attached to the bottom plane of the first layer. At first, a conventional DGS unequal Wilkinson power divider is designed according to the previous method on the first layer, and the second substrate is attached. The proposed DGS with double-layer substrate is described in detail and applied to 1:4 unequal dividers as an application example. The measured unequal Wilkinson power divider has an excellent agreement between prediction and measurement.

An Unequal Wilkinson Power Divider with Variable Dividing Ratio

In this paper, an unequal 1:N Wilkinson power divider with variable power dividing ratio is proposed. The proposed unequal power divider is composed of the conventional Wilkinson divider structure, rectangular-shaped defected ground structure (DGS), island in DGS, and varactor diodes of which capacitance is adjustable according to bias voltage. The high impedance value of microstrip line having DGS is going up and down by adjusting the bias voltage for varactor diodes. Output power dividing ratio (N) is adjusted from 2.59 to 10.4 for the unequal power divider with 2 diodes.

An Active Resonator Using Defected Ground Structure with Islands

A new resonator using active device and defected ground structure with islands (DGSI) is proposed. The active device is used for supplying the negative resistance which is one of key factors of the proposed active resonator. The negative resistance is realized by the series active device. The electrical characteristics of the proposed resonator with DGSI are improved by combining the negative resistance and the microstrip line with DGSI where the electric field is the most strong. It is shown that the measured improvement in S21 and Sll of the proposed active resonator with DGSI are 4.55 dB and 0.32 dB, respectively, at the resonant frequency compared to the previous DGSI resonator without active device.

An Unequal Power Divider with Adjustable Dividing Ratio

In this paper, an unequal 1:N Wilkinson power divider with adjustable dividing ratio is proposed. The proposed unequal power divider is composed of basic Wilkinson structure. It consists of rectangular-shaped defected ground structure (DGS), isolated island pattern in DGS, and varactor diodes of which capacitance depends on bias voltage. The characteristic impedance value of microstrip line having DGS goes up and down by controlling bias voltage for diodes, and consequently the power dividing ratio(N) is adjusted. The obtained N from measurement is which mean the proposed divider has adjustable unequal dividing ratio.

Design of a Highly Integrated Palette-type High Power Amplifier Module Using GaN Devices for DPD Application

This paper describes the design of a palette-type 60watt high power amplifier module using gallium nitride(GaN) devices with high power and efficiency performances for WiMAX and LTE systems. The line-up for the high gain amplifier module consists of the pre-amplifier stage with low power and high gain, 8watt GaN driving amplifier stage, and 60watt GaN high power amplifier stage of Doherty structure with two 30watt GaN devices. The obtained gain is 61.4dB with an excellent gain flatness of 0.075dB over 2.5~2.68GHz. GaN devices and the Doherty structure are adopted for the improvement of high efficiency and output power. The measurement for the fabricated high power amplifier module of palette type is performed using the widely known WiMAX signal all over the world. In the example of RRH(remote radio head) application of the fabricated amplifier module, the measured efficiency is 37~38% with the 10watts of modulated output power. It is shown that when the fabricated amplifier module is activated with a digital predistorter(DPD), the measured ACLR is better than 46dBc under the 10watts of modulated output power.

Optimization of Performances in GaN High Power Transistor Package

This paper describes the optimized output performances such as output power and the third order intermodulation in GaN high power transistor packages which consist of chip die, chip capacitors, and wire bonding. The optimized output power according to wire bonding techniques, and third order intermodulation performances according to wire bonding and bias conditions are discussed. In addition, it is shown through the nonlinear simulation that how the output performances are sensitive to the inductance values which are realized by wire bonding for matching network in the limited package area.

An Unequal Wilkinson Power Divider Using Defected Ground Structure in Double Layered Substrate

A novel 1:4 unequal wilkinson power divider using rectangular-shaped defected ground structure(DGS) in double layered substrate is proposed for removing the ground problem of DGS in packaging. Rectangular-shared DGS produces the transmission line having much higher characteristic impedance than standard microstrip line. The proposed unequal divider is composed of DGS and double layered substrate in order to be free from the ground problem of DGS patterns in packaging in metal housings. The second substrate is attached to the first substrate which contains DGS pattern on its ground plane at the bottom side to form the double layered substrate. In order to show the validity of the proposed DGS in the double layered substrate, a 1:4 unequal power divider is designed and measured. The predicted and measured performances are shown with an excellent agreement between them.