• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.6
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• pp.590-598
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• 2004

An active capacitance circuit which employs series feedback network for the implement of negative resistance and low noise operation is analyzed in depth and its application to low noise active RF BPF's is discussed. Whereas many authors reported a lot of circuits that embody negative resistance circuit most of them have concerns for the equivalent resistance and reactance value at the center frequency. In this case, it could be possible to face a problem that the negative resistance circuit becomes unstable, or have poor flatness in passband because of insufficient forecast for the negative resistance values as the frequency goes higher or lower. In this paper, we extracted the exact equivalent values of this circuit and analyzed the RF characteristics with the varying the values of active devices and feedback circuits and presented the method that the flatness of passband can be improved. We have designed a 4-pole active BPF, which has the bandwidth of 60 ㎒, 0.67 ㏈ insertion loss, 0.3 ㏈ ripple, and noise figure of 3.0 ㏈ at 1.99 ㎓ band.

• Journal of the Korean Institute of Telematics and Electronics
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• v.15 no.4
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• pp.33-37
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• 1978

A versatile negative resistance using one transistor, one photo-coupler and three resisters, which can be used as either a voltage controlled or current controlled negative resistance, is designed. The versatility is obtained by changing the transistor and one connection of the circuit. The negative resistance region is linear and its value can be varied by varying one of the three resistor values.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1591-1597
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• 2003

In this paper, Active Resonator Oscillator using active inductor and active capacitor with HEMTs(agilent ATF­34143) is designed and fabricated. Active inductor with ­25$\Omega$ and 2.4nH in 5.5GHz frequency band and Active capacitor with ­14$\Omega$ and 0.35pF is designed. Active Resonator Oscillator for LO in ISM band(5.8GHz) is designed with active inductor and active capacitor. Active Resonator Oscillator has been simulated by Agilent ADS 2002C. Active Resonator oscillator implemented on the substrate which has the relative dielectric constant of 3.38, the height of 0.508mm, and metal thickness of 0.018mm. This Active Resonator Oscillator shows the oscillation frequency of 5.68GHz with the output power of ­3.6㏈m and phase noise of ­81㏈c/Hz at the offset frequency of 100KHz.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.4
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• pp.275-281
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• 2003

A new neural oscillator has been designed and fabricated in an 0.5 ${\mu}{\textrm}{m}$ double poly CMOS technology. The proposed neural oscillator consists of a nonlinear variable resistor with negative resistance as well as simple transconductors and capacitors. The variable negative resistor which is used as a input stage of the oscillator consists of a positive feedback transconductors and a bump circuit with Gaussian-like I-V curve. The proposed neural oscillator has designed in integrated circuit with SPICE simulations. Simulations of a network of 4 oscillators which are connected with excitatory and inhibitory synapses demonstrate cooperative computation. Measurements of the fabricated oscillator chip with a $\pm$ 2.5 V power supply is shown and compared with the simulated results.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.1
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• pp.24-29
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• 2006

A new oscillatory neural circuit with computational function has been designed and been designed and fabricated in an $0.5{\mu}m$ double poly CMOS technology. The proposed oscillatory circuit consists of 3 neural oscillators with excitatory synapses and a neural oscillator with inhibitory synapse. The oscillator block which is a basic element of the neural circuit is designed with a variable negative resistor and 2 transconductors. The variable negative resistor which is used as a input stage of the oscillator consist of a bump circuit with Gaussian-like I-V curve. SPICE simulations of a designed neural circuit demonstrate cooperative computation. Measurements of the fabricated neural chip in condition of ${\pm}$ 2.5 V power supply are shown and compared with the simulated results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.748-753
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• 2002

In this paper, a new topology of a active capacitor is proposed in order to apply the resonator in the design of RF active bandpass filters. Through the noise analysis of the active capacitor, the optimized low noise design process is also presented, Due to the low noise performance of the proposed active bandpass filter, it can be used in the RF front-end of the receivers. In designed 2-stage active bandpass filter at 1.9 GHz shows insertion loss of 0 dB, noise figure of 2.6 dB, and OIP3 of 8 dBm.

• Journal of Korea Multimedia Society
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• v.6 no.2
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• pp.325-331
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• 2003

In this paper, we designed a spiral inductor and voltage controlled oscillator with the negative resistor for the bluetooth receiver by using 0.25$\mu\textrm{m}$ 1-poly 5-metal CMOS n-well process. The proposed inductor, which applies multi layer metal structure, is a structure that decreases resistance value by increasing he metal thickness. As the resistance value decreases, the quality factor Q has improved. Also, voltage-controlled oscillator is designed applying 1 port negative resistance, and changes its oscillating frequency by varying outside capacitor values. The simulation results show that oscillating frequency is 2.33~2.58GHz changing from 2pF to 14pF, and the oscillator has oscillating power over 0dBm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.12
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• pp.933-940
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• 2017

A wireless power transfer system with a negative impedance converter(NIC) was designed and tested. The system was investigated to identify the effects of ferrites and conductors. To improve the power transfer efficiency(PTE), the Q-factor of the transmitter was enhanced by the negative resistance generated by the NIC. The NIC was composed of an Op-Amp and resistors. The negative resistance was obtained with respect to a resistor connected in a feedback loop. The dimension of the Tx coil was $250mm{\times}250mm{\times}0.8mm$. The impedance and Q-factor were $31+j1874{\Omega}$ and 60, respectively. The negative resistance was selected to be $30{\Omega}$, and the Q-factor was increased to 900 by reduction of the transmitter resistance, which was about 15 times higher than that of a conventional transmitter. The measured PTE was greatly improved in comparison to that of a conventional system. These results demonstrate that the PTE is enhanced by using the NIC.

• Journal of the Korean Institute of Telematics and Electronics
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• v.10 no.2
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• pp.7-15
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• 1973

The operation behaviors of negative-resistance multivibrators. are described. The oscillation phenomena in monostable and bistable mode negative-resistance circuits are analyzed by using a analog computer. It is presented that voltage-controlled negative -resistance switching circuits may be in oscillation state for a time or parmanently by adding the bias voltage or trigger pulse. The results show that the care must be taken for this fact in the constructions of negative resistance switching circuits.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.1
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• pp.15-22
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• 1974

A new ternary full adder using the current controlled negative-resistance circuit is described. The full adder is constructed from the modified-half-adder which was devised by making use of a negative resistance circuit. This full adder makes the number of its gates decrease and makes its own speed increase in comparison with the full adders which had been introduced previously. It is convenient to construct to the integrated circuit because transistor, SBD(Schottky Barrier Diode) and resistors were used as the circuit elements.