• 전자공학회논문지C
• /
• 제34C권10호
• /
• pp.19-26
• /
• 1997

Novel class AB CMOS second-generation current conveyors (CCII) using 0.6.mu.m n-well CMOS process for high-frequency current-mode signal processing were developed. The CCII for low power operation consists of a class AB push-pull stage for the current input, a complementary source follower for the voltage input, and a cascode current mirror for the current output. In this architecture, the two input stages are coupled by current mirrors to reduce the current input impedance. Measurements of the fabricated CCII show that the current input impedance is 875.ohm. and the bandwidth of flat gain when used as a voltage amplifier extends beyond 4MHz. The power dissipation is 1.25mW and the active chip area is 0.2*0.15[mm$\^$2/].

• 전기의세계
• /
• 제14권1호
• /
• pp.26-34
• /
• 1965

The radiation patterns and impedance of the half wave solt on the wide side of rectangular wave guide are analyzed. The measuring methods and procedures are described. And that the experimental data of the pattern and impedance of the slot are presented which are consistent with the theoretical values. The causes of error are also considered and are believed to be tolerable for the pattern and input impedance measurements. The usefulness of the slot antenna tested are also described.

• 대한전자공학회논문지
• /
• 제26권11호
• /
• pp.1728-1735
• /
• 1989

A design procedure for microstrip bandpass filters using step impedance resonators (SIR's) and tapped input/output to a conventional parallel coupled line bandpass filter is presented. The filter configuration consisting of both half-wavelength and SIR's suppreses to spurious resonance response near the second harmonics, while tapping techniques offer benefit in situations where the impractical. The measured frequency responses of the designed filter are in close agreement with the computed responses.

• 한국전자파학회지:전자파기술
• /
• 제2권4호
• /
• pp.10-16
• /
• 1991

A microstrip bandpass filter using stepped impedance resonators and tapped input / output is realized with Teflon substrate, whose center frequency is 3.5 GHz and fractional bandwidth is 20%. In order to realize a wider bandwidth of 30%, the Crystal's design method and the input / output tapping scheme are used. Another microstrip filter designed as mentioned above is realized with Epsilam-10 substrate. This case shows good agreement between the theoretical responses and the measured ones.

• Journal of electromagnetic engineering and science
• /
• 제4권2호
• /
• pp.68-71
• /
• 2004

The limitation of telegrapher's equations for analysis of nonuniform transmission lines is investigated here. It is shown theoretically that the input impedance of a nonuniform transmission line cannot be derived uniquely from the Riccati equation only except for the exponential transmission line of a particular frequency-dependent taper. As an example, the input impedance of an angled two-plate transmission line is calculated by solving the telegrapher's equations numerically. The numerical results suffer from larger deviation from its rigorous solution as the plate angle increases.

• 동력기계공학회지
• /
• 제13권2호
• /
• pp.71-82
• /
• 2009

This paper presents a real-time haptic rendering method for a realistic force feedback in a remote environment with varying communication time-delay. The remote environment is assumed as a virtual environment based on a computer graphics, for example, on-line shopping mall, internet game and cyber-education. The properties of a virtual object such as stiffness and viscosity are assumed to be unknown because they are changed according to the contact position and/or a penetrated depth into the object. The DARMAX model based output estimator is proposed to trace the correct impedance of the virtual object in real-time. The output estimator is developed on the input-output relationship. It can trace the varying impedance in real-time by virtue of P-matrix resetting algorithm. And the estimator can trace the correct impedance by using a white noise that prevents the biased input-output information. Realistic output forces are generated in real-time, by using the inputs and the estimated impedance, even though the communication time delay and the impedance of the virtual object are unknown and changed. The generated forces trace the analytical forces computed from the virtual model of the remote environment. Performance is demonstrated by experiments with a 1-dof haptic device and a spring-damper-based virtual model.

• 대한전자공학회논문지
• /
• 제11권6호
• /
• pp.38-43
• /
• 1974

임의의 전원임피이던스와 임의의 부하임피이던스 사이에 삽입할 때 입력반사계수가 가급적 넓은 주파수범위에서 최소가 되는 임피이던스 정합용 불균일선로 섹션을 설계하는 문제를 고찰하였다. 고려대상의 불균일선로는 수학적으로는 특수한 종류에 속하는 것이나 실제적으로는 완만하게 변하는 거의 모든 전송선로를 포괄할 수 있다. 입력반사 계수의 계산에서는 선로의 ABCD 파라미터의 테일러 급수전관식을 이용하였다. 그리고 설계문제를 비선형 구속조건을 가진 비선형 프로그래밍 문제로서 수식화하였으며 이것을 수차적비구속 최소법(Sequential Unconstrained Minimigation Technique)과 Fletcher-Powell 방법을 병용하여 풀었다. 결과적으로 이제까지 광대역 임피이던시 정합편 전송선제로서 발표된 가장 우수한 것보다 훨씬 특성이 개선된 것을 얻을 수 있었다.

• 한국전기전자재료학회논문지
• /
• 제21권8호
• /
• pp.776-781
• /
• 2008

In this study, ubiquitous health care system attaching in chair to monitor ECG for health care was developed at the unconsciousness state. The system conveniently and simple measured ECG at non-consciousness. We measured the contact impedance to skin-electrode of metal mesh electrodes of the system. Contact impedance enable the electrode to use for ECG measurement. The results are that the impedance of the metal mesh electrodes according to sizes is low when the size is 4$cm^2$. As the result, when the size of the metal mesh electrode is 4$cm^2$, the electrode is fit for ECG measurement. We can acquired by positing the arm on the metal mesh electrode. The ECG signal was detected using a high-input-impedance bio-amplifier, and then passed filter circuitry. The measured signal transmitted to a PC through the bluetooth wireless communication and monitored. Data of the non-constrained ECG system attaching in chair is noise-data when comparing metal mesh electrode with the Ag/Agcl electrode but the data is significant to monitor ECG for check the body state.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권12호
• /
• pp.620-625
• /
• 2004

In this paper, we studied the emissive electric field due to the communication signal and the noise in medium voltage power-line. There are many types of conductive noise in power-line channel, which gives rise to radiation. And if the DMT carrier signal was excited, the current by this term was added to the current by noise and, generate radiation. We calculated input impedance by means of signal input network model of medium voltage power-line channel for calculating these currents. We calculated currents by input impedance and, calculated the emissive electric field by this calculated currents. From the measurement results, we knew that the measured results are very similar to the calculated results and if the input signal power level was higher than -40 dBm, the emissive electric field exceeds FCC radiation limit level 69.5 dB$\mu$V/m.

• 전자공학회논문지C
• /
• 제34C권9호
• /
• pp.1-9
• /
• 1997

Novel class A CMOS second-generation current conveyors (CCII) using 0.6.mu.m n-well standard CMOS process for high-frequency current-mode signal processing were developed. The CCII consists of a regulated current-cell for the voltage input and a cascode current mirror for the current output. In this architecture, the two input stages are coupled by current mirrors to reduce the current input impedance. Measurements of the fabricated cCII show that the current input impedance is 308 .ohm. and the 3-dB cutoff frequency when used as a voltage amplifier extends beyond 10MHz. The linear dynamic ranges of voltage and current are from -0.5V to 1.5V and from -100.mu.A to +120.mu.A for supply voltage V$\_$DD/ = -V$\_$SS/=2.5V, respectively. The power dissipation is 2 mW and the active chip area is 0.2 * 0.2 [mm$\^$2/].