• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.12 s.103
• /
• pp.1186-1193
• /
• 2005

In this paper, a new 3 dB branch line hybrid using asymmetric spiral-shaped defected ground structure(DGS) microstrip is proposed. The proposed branch line hybrid suppresses the 2nd and the 3rd harmonic component effectively. Also a DGS $\lambda$/4 bias line that can suppress high frequency harmonics as well as low frequency intermodulation component is proposed. With the harmonic termination tuner using the proposed hybrid and the harmonic blocking bias line, the 2nd and the 3rd harmonic components of the fabricated amplifier that operated in IMT-2000 basestation transmitting band were suppressed up 25 dB and 27 dB, respectively. The proposed harmonic load-pull setup of amplifier is more easily accomplished with proposed circuits than the previous.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.22 no.6
• /
• pp.97-102
• /
• 1985

A new microwave transmission line frequency discriminator in MIC is described, which is composed of a branch-line hybrid 3dB coupler, a λ/2-short stub and a λ/4-opcn stub. It is experimentally verified that the discriminator is linear in a 400 MHz bandwidth at center frequency 4.94 GHz and has return loss more than 15dB in that range.

• ETRI Journal
• /
• v.33 no.6
• /
• pp.897-903
• /
• 2011

A hybrid ${\Delta}{\Sigma}$ modulator for audio applications is presented in this paper. The pulse generator for digital-to-analog converter alleviates the requirement of the external clock jitter and calibrates the coefficient variation due to a process shift and temperature changes. The input resistor network in the first integrator offers a gain control function in a dB-linear fashion. Also, careful chopper stabilization implementation using return-to-zero scheme in the first continuous-time integrator minimizes both the influence of flicker noise and inflow noise due to chopping. The chip is implemented in a 0.13 ${\mu}m$ CMOS technology (I/O devices) and occupies an active area of 0.37 $mm^2$. The ${\Delta}{\Sigma}$ modulator achieves a dynamic range (A-weighted) of 97.8 dB and a peak signal-to-noise-plus-distortion ratio of 90.0 dB over an audio bandwidth of 20 kHz with a 4.4 mW power consumption from 3.3 V. Also, the gain of the modulator is controlled from -9.5 dB to 8.5 dB, and the performance of the modulator is maintained up to 5 nsRMS external clock jitter.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.17 no.6
• /
• pp.78-85
• /
• 1980

A symmetrical 3-dB quadrature hybrid circuits, consisting mainly of bifilar pair of taitoted wires, is described. A cascade of two such hybrid circuits can achieve an octave bandwidth hybrid circuit with a small coupling loss. Since the proposed type is simple, compact, and low In cost 1 its applicarion may be preferred to the more common coaxial line or printed -circuit type hybrid version in the frequency region below 1 GHz. This study provides a design method for a hybrid circuit mixing two different antenna signals for the anti - ghosting of television signal.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.5
• /
• pp.2045-2049
• /
• 2018

An antenna arrays for a satellite navigation systems require more antenna elements to mitigate multiple jamming signals. In order to maintain the small array size while increasing the number of antenna elements, miniaturization technique is essential for antenna design. In this work, an electrically small circular microstrip patch antenna with a 3 dB hybrid coupler is designed as an element antenna, where the 3 dB hybrid coupler can yield the circularly polarized radiation characteristic. The miniaturized element antenna typically has too large capacitance in GPS L1 and GLONASS G1 bands, making it difficult to match with a single stand-alone non-Foster matching circuit (NFMC) in a stable state. Therefore, we propose a new matching technique, referred to as the hybrid matching method, which consists of a NFMC and a passive circuit. This passive tuning circuit manages reactance of antenna elements at an appropriate capacitance without a pole in the operating frequency range. The antenna array is fabricated, and the measured results show a reflection coefficient of less than -10 dB and an isolation of greater than 50 dB. In addition, peak gain of the proposed antenna is increased by 22.3 dB compared to the antenna without the hybrid matching network.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.45 no.4
• /
• pp.86-93
• /
• 2008

A low-power, low-noise, highly-linear hybrid balun circuit is proposed for 2.4-GHz fully differential CMOS direct conversion receivers. The hybrid balun is composed of a passive transformer and loss-compensating auxiliary amplifiers. Design issues regarding the optimal signal splitting and coupling between the transformer and compensating amplifiers are discussed. Implemented in $0.18{\mu}m$ CMOS process, the 2.4 GHz hybrid balun achieves 2.8 dB higher gain and 1.9 dB lower noise figure than its passive counterpart and +23 dBm of IIP3 only at a current consumption of 0.67 mA from 1.2 V supply. It is also examined that the hybrid balun can remarkably lower the total noise figure of a 2.4 GHz fully differential RF receiver only at a cost of 0.82 mW additional power dissipation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.7
• /
• pp.713-718
• /
• 2008

A modified broad-band ring hybrid balun with additional two shorted $\lambda$/4 stubs is proposed. The proposed balun is a modified version which has additional two shorted $\lambda$/4 stubs to compensate phase and amplitude imbalances of conventional ring hybrid coupler. To demonstrate the validity of the proposed balun, a balanced Schottky-diode frequency doubler is designed and measured. Measurement data show that the proposed frequency doubler has around 10 dB conversion loss and more than 30 dB fundamental suppression over an input range of $1.6{\sim}2.35\;GHz$.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.5
• /
• pp.3139-3145
• /
• 2014

This paper describes the design of a size-reduced ring hybrid coupler for microwave band using an artificial dielectric substrate(ADS). ADS structure adopts the second substrate on which has lots of the metalized via-holes. The effective capacitance and effective dielectric constant per unit length of ADS increases compared to the normal substrate due to the via-holes. This enables the physical length of microstrip transmission line to be reduced by adopting ADS instead of the normal substrate. In order to present an example of size-reduction of microwave wireless circuit by ADS, a size-reduced 3GHz ring hybrid coupler is designed, fabricated and measured in this work. The designed coupler has the smaller size from the normal one by 65% due to the ADS, while no critical degradation from ideal performances is observed. The measured power division ratio at two output ports are -3.05dB and -3.135dB, respectively. In addition, the phase differences are 3o for in-phase division and 176o for out of phase split. The measured performances are so similar to ideal ones, and prove the design of size-reduced ring hybrid coupler using ADS is successful.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.264-265
• /
• 2007

In this paper, we deal with a hybrid dual band low noise amplifier with tunable matching circuits for a Radio Frequency Identification(RFID) reader operating at 433MHz and 912MHz. The tunable matching circuit consists of the microstrip line, SMD component and varactor. Simulation results show that the S21 parameter is 17dB and 7.91dB at 433MHz and 912MHz, respectively. The noise figure is also determined to 3.56dB and 5.58dB at the same frequencies with a power consumption of 19.36mW.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.5B no.1
• /
• pp.39-42
• /
• 2005

Though full 3D analysis is the proper method to analyze the hybrid stepping motor (HSM), it has weak points in the areas of computation time and complexity. This paper introduces 2D FEA using a virtual magnetic barrier for the axial cross section to save computation time. For the purpose of 2D FEA, the virtual magnetic barrier and equivalent permanent magnet model of HSM are proposed. This result is compared with that of experimental and 3D analysis, considered as a reference result.