• The Journal of Korean Institute of Communications and Information Sciences
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• v.7 no.1
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• pp.10-17
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• 1982

Recently, there has been a great interest in the realization of analog fiters using switched and fixed capacitors and active elements. It is known that a switched capacitor has an performance much better that a resistor in the characteristics of temperature and linearity, and can be fabricated on the much smaller area than the resistor. In this paper all the resistors in the gyrator filter network are relpaced by the switched capacitors for an SC-Gyrator filter circuit can be fully integrated into a single chip by using MOS technology. By experiments we show that the response of designed SC-Gyrator filter is much similar to that of its protorype gyrator filter.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.7
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• pp.42-49
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• 1993

In this paper, switched-capacitor building block presented which are suitable for implementation in GaAs MESFET technology. They include a current source, a gain stage, and an operational amplifier. Switched-capacitor design techniques are discussed that minimize filter sentsitivity to finite gain of the GaAs operational amplifier. Simulation results are presented on third-order elliptic lowpass ladder filter at a sampling rate of 5GHz.

• Journal of the Korean Institute of Telematics and Electronics
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• v.18 no.4
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• pp.1-11
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• 1981

This paper proposes a method of generalizing the clocking scheme in the Switched Capacitor Filter(SCF) design using Voltage Inverter Switches (VIS's). Parallel RC and RL elements, and parallel LC resonators can be implemented by the proposed clocking schemes Applying these new elements and the generalized clocking schemes to the SCF design, the total number of required operational amplifiers and capacitors can be reduced. Experimental results of a band- stop filter and a low-pass filter using a new type grounded VIS show good agreements with t he theoretical characteristics.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.333-336
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• 2000

Modem standard CMOS process technology suffer from so large amount of PVT i.e process, voltage and temperature variation over 30% of its desired value that accurate resistor value is hard to be achieved. A filter using switched-capacitor(SC) circuit has a time constant proportional to relative capacitor area ratio rather than its absolute value. If the PLL's loop filter were made out of SC circuit, there could be much less PVT variation problem. Furthermore, programmability on the loop filter can be achieved In this paper, we present the PLL with SC loop filter. The accuracy provided by SC filter would be helpful to enhance PLL's locking behaviour.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.9 no.1
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• pp.30-38
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• 1984

In this paper, we designed the programmable 2nd order switched capacitor filter that the center frequency can be varied linearly with the clock frequency, and that the peak gaion and the selectivity can be controlled with digital signal by the capacitor array. In addition, speech synthesizer system was constructed with this filter, korean consonants being synthesized. Therefore, this filter shows the possibility that most Korean language sounds can be synthesized in the real time mode.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.4 no.1
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• pp.25-31
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• 1979

All the resitors in the active RC filter networks can be relplaced by the switched capacitors. Therefore, An SC filter circuit can be fully integrated using MOS technology. A switched capacitor is much better than a resistor in temperature and linearity characteristics, and the former can be fabricated on the much smaller area then the latter. In this paper, It is given the generalized disign method of the active SC filter from the active RC filter using Bilinear Z-transformation. By SC filtering Techniques using Bilinear Z-transform, It enalbes us to realize the FDNR and Gyrator filters, which could not be realized in the exsisting designs, and it permits the processing of signals at much higher frequenies that many previous designs do. Experiments show that the response of the SC active filter is similiar to that of its prototype active RC filter.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.4
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• pp.148-153
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• 2003

In this paper, the low voltage 3V Sigma-Delta Digital Analog Converter(DAC) is designed for using in the transmitter of ADSL analog front-end. We have developed the CMOS DAC according to ANSI T1.413-2(DMT) standard specifications of the chip. The designed 4th-order DAC is composed of three block which are 1-bit DAC, 1st-order Switched-Capacitor filter and analog active 2nd-order Resistor-Capacitor(RC) filter. The HSPICE simulation of the designed DAC showing 65db SNR, is connected with 1.1MHz continuous lowpass filter. And also, we have performed the circuits verification and layout verification(ERC, DRC, LVS) followed by fabrication using TSMC 2-poly 5-metal p-substrate CMOS $0.35{\mu}m$ processing parameter. Finally, the chip testing has been performed and presented in the results.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.4
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• pp.477-483
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• 1986

This paper studies the design of a CMOS operational amplifier for the switched capacitor filter by computer simulation, and presents the results of measurement. The operational amplifier composed of two stages is fabricated in the CMOS digital process. The DC voltage gain of the operational amplifier is 66dB, and the unity gain bandwidth is 833kHz. These results satisfy the performance requirmance requirements for the operational amplifier of the switched capacitor filter.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.12
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• pp.472-479
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• 1984

In order to realize the simple and economic 3rd order LPF using switched-capacitor(SC), we proposed the 3rd order RC LPF using a OP amplifier and realized the 3rd order SC LPF by replacing all the resistors in the RC LPF to SC. The frequency response of SC LPF was compared with the that of RC LPF. As a result, it was found that the response of realized SC LPF is almost similar to that of RC LPF.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1521-1524
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• 1987

The performance of SCF can be improved with the Op-AMP which has the properties of high speed, large slew rate, and lower power dissipation. The OP-AMP used for SCF will be presented. For illustration, using this OP-AMP 5-th order LPF is designed.