Browsing by Author "Chang, Tsu"

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A 2.4 GHz CMOS Power Amplifier Using Asymmetric MOSFETs
(2012)
Liu, Szu-Ling
;
Huang, Yu-Chien
;
Chen, Ying-Jen
;
Chang, Tsu
;
Chin, Albert
In this paper, a two-stage 2.4 GHz power amplifier (PA) using the high-breakdown-voltage asymmetric NMOSFETs was implemented in a 0.18-mu m CMOS technology. In this process, the conventional NMOSFETs have a drain-to-source breakdown voltage (BVdss) about 3.5V, therefore restricting the available output power in PA designs. However, by using the special asymmetric NMOSFETs in the proposed PA, the circuit can safely operate at a supply voltage from 1.8 to 2.75V. Under a 2.75V operation, good power performances include a power gain of 20.4 dB, an output 1-dB compression point (P-out,P-1dB) of 21.5dBm and a power-added-efficiency (PAE) of 29.6%.
A Low-Power K-Band CMOS VCO With Four-Coil Transformer Feedback
(2010-08-01)
Liu, Szu-Ling
;
Chen, Kuan-Han
;
Chang, Tsu
;
Chin, Albert
;
電子工程學系及電子研究所
A K-band low-power and low-phase-noise voltagec-ontrolled oscillator (VCO) is presented in this letter. By utilizing four-coil transformer feedback and forward body bias topology, good performances are obtained under a low-power supply with a 5.1% tuning range and a phase noise of -109.8 dBc/Hz at 1 MHz offset from the 21.37-GHz carrier frequency. The core circuit of this VCO only consumes 3.5 mW with a 0.6-V supply voltage and a 0.55-V body bias.
Crystallized Ohmic Contact Effect in AlGaN/GaN High Electron Mobility Transistor
(2013-08-01)
Liao, Sheng Yu
;
Chang, Tsu
;
Hsu, Hsiao-Hsuan
;
Cheng, Chun-Hu
;
Chang, Liann-Be
In this study, we investigate the grain size effect of high electron mobility transistor devices with ohmic contact metals of stacked Ti/Al/Ni/Au and Ti/Al/Mo/Au. In addition to a comparison of electrical characteristics, the ohmic contacts were also examined by a scratch test for the observation of adhesion behavior. The experimental results demonstrate that the metal grain size is strongly dependent on metal adhesion, which may lead to bonding issues. Moreover, the grain-induced lateral stress lowers the drive current and increases the off-state current owing to the degraded gate swing and transconductance of transistor switching characteristics. (C) 2013 The Japan Society of Applied Physics
Improved Radio Frequency Power Characteristics of Complementary Metal-Oxide-Semiconductor-Compatible Asymmetric-Lightly-Doped-Drain Metal-Oxide-Semiconductor Transistor
(2010)
Chang, Tsu
;
Kao, Hsuan-Ling
;
Chen, Y. J.
;
Chin, Albert
;
電子工程學系及電子研究所
We have characterized and modeled the radio frequency (RF) power performance of a 0.18 mu m asymmetric-lightly-doped-drain metal-oxide-semiconductor field-effect transistor (LDD MOSFET). In comparison with the conventional 0.18 mu m MOSFET, this asymmetric-LDD device shows a larger power density of 0.54 W/mm, and 8 dB better adjacent channel power ratio (ACPR) linearity at 2.4 GHz from the improved twice DC breakdown voltage of 6.9 V. These significant improvements of RF power performance in the asymmetric-LDD transistor are important for the medium RF power amplifier application. (C) 2010 The Japan Society of Applied Physics
Radio Frequency Power Performance Enhancement for Asymmetric Lightly Doped Drain Metal-Oxide-Semiconductor Field-Effect Transistors on SiC Substrate
(2010)
Chang, Tsu
;
Kao, Hsuan-ling
;
Liu, S. L.
;
Deng, Joseph D. S.
;
Horng, K. Y.
In this paper we report the DC characteristics and radio frequency (RF) power performance improvement as high as 6.6% of asymmetric lightly doped drain metal-oxide-semiconductor field-effect transistors (asymmetric LDD MOSFET, AMOSFET) with 50-mu m-thick silicon substrates on SiC substrates. The self-heating and parasitic effects of large size AMOSFETs with 50-mu m-thick silicon on SiC substrates are reduced owing to good heat dissipation and less lossy behaviors of thinned silicon substrates and SiC substrates. Therefore, the power gain, saturation output power, and power added efficiency of AMOSFETs with 50-mu m-thick Si substrates mounted on SiC substrates is improved. (C) 2010 The Japan Society of Applied Physics
RF power performance of asymmetric-LDD MOS transistor for RF-CMOS SOC design
(2007-06-01)
King, Ming-Chu
;
Chang, Tsu
;
Chin, Albert
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This letter presents a new asymmetric-lightly-doped-drain (LDD) metal oxide semiconductor (MOS) transistor that is fully embedded in a CMOS logic without any process modification. The radio frequency (RF) power performance of both conventional and asymmetric MOS transistor is measured and compared. The output power can be improved by 38% at peak power-added efficiency (PAE). The PAE is also improved by 16% at 10-dBm output power and 2.4 GHz. These significant improvements of RF power performance by this new MOS transistor make the RF-CMOS system-on-chip design a step further.