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Hong-Teuk Kim,
Ki-Hong Lee,
Hyung-Kyu Choi,
Ji-Youn Choi,
Kyung-Hak Lee,
Jin-Pil Kim, Gi-Hyon Ryu,
Yong-Jocin Jeon,
Choong-Soo Han,
Keechul Kim,
Kyungho Lee
Microwave Conference, 2004. 34th European; 11/2004
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ABSTRACT: A highly efficient code division multiple access power amplifier of parallel amplification architecture exhibits power added efficiency of 17% and adjacent channel power ratio less than -51 dBc at an output power of 16 dBm. The output impedances of the low/high-power amplifier chains are very low because the collector impedances of the "OFF-state" power heterojunction bipolar transistors are low and the low impedances are transformed into even lower ones by low-pass output matching circuits. The low impedances are boosted up using a compact lumped λ/4 transmission line and the chains are operated independently without producing any significant performance degradation.
IEEE Microwave and Wireless Components Letters 10/2004; · 1.72 Impact Factor
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ABSTRACT: Transmission lines of very low characteristic impedance (Z<sub>0</sub>) are fabricated and analyzed. The transmission lines are fabricated on the benzo-cyclo-butene (BCB) films of a low dielectric constant. Two types of coplanar waveguide (CPW) structures are fabricated, which include bottom-ground and double-ground type. Measurement shows that Z<sub>0</sub> values for each CPW type are 7.3 and 9.4 Ω, respectively, at a signal line width of 100 μm. When the ratio between the spacing of bottom-ground and the signal line width becomes greater than 2.5, the Z<sub>0</sub> is nearly saturated. In addition, thin film microstrip lines fabricated using the BCB insertion layers show very low Z<sub>0</sub> of 25.5 Ω, and this impedance is ∼64 % of the values obtained from the BCB-based CPW structures of the same line width.
Optoelectronic and Microelectronic Materials and Devices, 2002 Conference on; 01/2003
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ABSTRACT: A new Marchand balun for MMIC is proposed which uses air-gap
stacked structures and does not need any dielectric process. To design
the newly proposed Marchand balun, simple graphical design method was
used, which is based on Tsai and Gupta's generalized coupled lines
model. The simple design results were compared with a general full-wave
analysis. In this case, HP-Momentum simulator was used
Microwave Symposium Digest, 2001 IEEE MTT-S International; 02/2001
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ABSTRACT: A simple broadside-coupled line structure for MMIC is proposed
which uses air-gap stacked microstrip lines and does not require any
dielectric process. The analysis and optimization of the coupled line
structure were performed by using an electromagnetic simulator. The
fabricated 3-dB coupler shows broad-band characteristics (23-45 GHz)
with the coupling loss of 3.33±0.46 dB and the transmission loss
of 3.73±0.43 dB
IEEE Microwave and Guided Wave Letters 02/2000;
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ABSTRACT: This paper represents the device parameter influence of GaAs PHEMT
with different gate lengths on switching performance and its application
in DC-50GHz wide-band SPST monolithic switch ICs. From the
characteristic of GaAs PHEMT and monolithic switch, especially, it is
proved experimentally that source-to-drain capacitance dependent on gate
length is a very important characteristic for improving the isolation
performance of GaAs PHEMT switch at high-impedance state
Microwave Symposium Digest. 2000 IEEE MTT-S International; 02/2000
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ABSTRACT: A novel low impedance line for MMIC is proposed which uses air-gap
stacked microstrip structure and does not require any dielectric
process. The proposed transmission line has the width of about 1/3 times
that of the conventional microstrip line. It shows lower transmission
loss than thin film low impedance transmission line. The proposed
transmission line was used to the matching stub of the balanced
amplifier MMIC based on the 0.25 μm gate GaAs P-HEMT technology,
reducing the chip size by 69% compared with the conventional
microstrip-based design
Microwave Symposium Digest. 2000 IEEE MTT-S International; 02/2000
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ABSTRACT: A cascode distributed amplifier IC has been designed and
fabricated using a 0.25 μm non-recessed self-aligned gate (SAG) GaAs
P-HEMT and coplanar IC technology. Through the SAG process and an
optimised epitaxial layer structure, excellent device performance has
been obtained without gate recessing, and the device yield and
uniformity were high enough for IC applications. The fabricated
seven-stage cascode distributed amplifier IC has an 11 dB gain and a 3
dB bandwidth of 50 GHz with excellent uniformity in the IC
characteristics. The gain-bandwidth product obtained (180 GHz) is
comparable or even superior to that of the previous distributed
amplifiers based on a shorter-length, recessed gate GaAs P-HEMT
Electronics Letters 11/1999; · 0.96 Impact Factor
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ABSTRACT: This paper proposes a new, differential-pair circuit configuration
of the floating active inductor. Since this technique leads to a
symmetric structure, the derived floating active inductor exhibits fully
symmetrical 2-port characteristics at all frequencies like an ideal
inductor, and it also shows more than four times wider dynamic range
compared to the conventional circuit. In addition, this configuration
can be easily extended to the negative inductance circuit. The simple
circuit analyses and simulation results are presented
Circuits and Systems, 1997. ISCAS '97., Proceedings of 1997 IEEE International Symposium on; 07/1997
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Hong-Teuk Kim,
Ki-Hong Lee,
Hyung-Kyu Choi,
Ji-Youn Choi,
Kyung-Hak Lee,
Jin-Pil Kim, Gi-Hyon Ryu,
Yong-Joon Jeon,
Choong-Soo Han,
Keechul Kim,
Kyungho Lee
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ABSTRACT: New architectures of the dual chain InGaP
MMIC power amplifiers without/with automatic bias
current control (ABC2) have been developed for
improving efficiency in the low-power region while
maintaining the high linearity for all Pout regions. For
low standby current less than 25 mA, the amplifiers
initially operate using small HBT arrays. For small
chip size, high load impedance in low-power region,
and efficient power combining in high-power region,
phase-compensating L-C matching circuits using lowpass
and high-pass networks are used. A new simple
power detection and bias current control circuit is
employed to the power amplifier, resulting in
automatic gain control for Pout variation. The
fabricated ABC2 power amplifier module shows good
ACPR more -48 dBc over all Pouts, and high efficiency
of 6 % PAE (conventional 3.5~4%) at Pout=9 dBm,
and 37.5 % PAE at Pout=28 dBm.
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ABSTRACT: A new FET extrinsic parameter extraction method is proposed, in which all the extrinsic elements can be determined directly from the S-parameters at pinch-off bias. It utilizes the measurement data of various gate-width FET's and the simple scaling property of each equivalent circuit parameters, eliminating some complex measurement steps such as forward gate bias measurement. Since the gate-width scaling characteristics are taken into account, the proposed method can be utilized for the MMIC design where the optimization of the FET gate-width is important. The proposed method was successfully applied to the modeling of 0.25 um GaAs P-HEMT.
