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A planar‐type dielectric resonator and filter using LTCC process
Yim, Jounghyun,Kang, Daehyun,Son, Seokho,Kim, Bumman Wiley Subscription Services, Inc., A Wiley Company 2007 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.49 No.3
<P><B>Abstract</B></P><P>A new structure planar‐type dielectric resonator (PDR) with high Q has been developed using an LTCC process. The PDR consists of two different dielectric constant materials, a hollow patch center ground plane in the middle of the cavity layer and shielded cavity metals. The realized PDR shows a high unloaded‐<I>Q</I> factor of about 1920 at 34.3 GHz. We also developed a dual mode band‐pass filter using the proposed PDR, demonstrating a compact filter at a millimeter‐wave band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 578–581, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22206</P>
High-Efficiency Push–Pull Power Amplifier With High Operation Voltage
Jounghyun Yim,Ildu Kim,Daehyun Kang,Bumman Kim THE INSTITUTE OF ELECTRICAL ENGINEERS 2007 IEEE Microwave and Wireless Components Letters Vol. No.
<P>A highly efficient push-pull class D power amplifier (PA) with a high operation voltage is presented. The high voltage is realized by stacking dc biases of two push-pull amplifiers through the virtual ground point, while the radio frequency powers are series combined. The drain supply voltage is increased to 44V, which is double of the rated bias voltage (22V) of the active devices. The LDMOS PA provides an output power of 40.6dBm with a power-added efficiency (PAE) of 58.7% at 836.5MHz. Each push-pull amplifier provides 38-dBm output with a PAE of 64%</P>
A <tex> $\Delta\Sigma$</tex> -Digitized Polar RF Transmitter
Jinsung Choi,Jounghyun Yim,Jinho Yang,Jingook Kim,Jeonghyun Cha,Daehyun Kang,Dongsu Kim,Bumman Kim IEEE 2007 IEEE transactions on microwave theory and techniqu Vol.55 No.12
<P>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 noise-shaping characteristic. It enables the use of a highly efficient switching amplifier with high linearity. For demonstration, the overall transmitter is implemented and tested with a code-division multiple-access IS-95A signal. The class-D and class-F amplifiers are designed and compared for the optimum operation. The experimental results show that the amplifier with small device size is suitable for this application because of the fast switching requirement. For the class-F amplifier, the measured power-added efficiency is 51.7% at 22.1 dBm and the overall efficiency (considering the amplified quantization noise) is 31%. The adjacent channel power ratios at 885 kHz and 1.98 MHz are lower than -44.9 and -55.6 dBc at the output power range from 10.8 to 22.1 dBm without any pre-distortion techniques. The overall efficiency is improved to 48.6% with a three-level quantized DeltaSigma modulator. The results clearly show that the highly efficient switching mode PA can be controlled efficiently using a digital signal from the DeltaSigma envelope modulation technique.</P>