• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.4
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• pp.20-30
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• 2001

A novel 200 MHz CMOS transconductor using translinear cells is proposed. The proposed transconductor consists of voltage followers and current followers based on translinear cells and a resistor. For wide applications, a single-input single-output, a single-Input differential-output, and a fully-differential transconductor are systematically designed, respectively. The theory of operation is described and computer simulation results are used to verify theoretical predictions. The results show that the fully-differential transconductor has a linear input voltage range of ${\pm}2.7$ V, a 3 dB frequency of 200 MHz, and a temperature coefficient of less than 41 $ppm/^{\circ}C$ at supply voltages of ${\pm}3$ V. In order to certify the applicability of the fully-differential transconductor, A ladder-type 3th-order cllitic low pass filter is also designed based on the inductance simulation method. The filter has a ripple bandwidth of 22 MHz, a pass-band ripple of 0.36 dB, and a cutoff frequency of 26 MHz.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.357-360
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• 1999

A 20 MHz CMOS continuous low-pass filter using simulated floating inductor consisted of two fully-differential transconductors and a capacitor is presented. The theory of operation is described and simulation results show close agreement between predicted behaviour and experimential performance. Simulation results show that the filter has ripple bandwidth of 22 MHz, pass-band ripple of 0.36 ㏈. and cutoff frequency of 26 MHz at supplay voltage of $\pm$3 V. The power dissipation is 19.2 ㎽.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.9
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• pp.22-26
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• 1994

In this paper a method of designing FIR filters without digital arithmetic operationsi is persented. The filter coefficients are represented by resistors combined with a differential amplifier. With this method an FIR filter can be simply impemented without refering to complex digital arithmetic operations. Furthermore, in this scheme, no additional D/A converter is needed for D/A conversion. Spectral response response of a pulse shaping filter of 17 coefficients is shown as an illustration.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.913-916
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• 2003

In many cases, ac line EMI filters are designed by trial and error method. Thus, designing a filter is a time-consuming process. To overcome the problem, the newly analytical design procedure is proposed in this paper. Using the modeling circuit of each filter components, the filter design is carried out applicable to both common-mode (CM) and differential-mode (DM). These are verified through the experimental results.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.794-796
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• 1993

This paper deals with the characteristic analysis of noise filter for the reduction of conduction noise, especially, common-mode noise. Attenuation in the system containing noise filter is analyzed and equivalent circuits for common- and differential- mode noise are derived. To clarify the effects by parasitic components of the inductor and capacitor, digital simulations using Design Center are carried out.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.10
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• pp.1-7
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• 2010

A new frequency offset estimation algorithm for chirp spread spectrum based on matched filter is proposed. Generally, the differential phase between successive symbols is used for the conventional frequency offset estimation algorithm. However, if the conventional frequency offset estimation algorithm is used for CSS, phase ambiguity arises because of long symbol duration and guard time. The phase ambiguity causes performance degradation of matched filter since the received signal is corrupted by the integer frequency offset. In this paper, we propose a new frequency offset estimation algorithm which separates integer and fractional frequency offset estimation for removing the phase ambiguity. The proposed algorithm estimates the integer frequency offset by using differential phase between matched filtering results of sub-chirps and successive symbols. Then, the fractional frequency offset is estimated by using the differential phase between successive symbols Simulation results show that the proposed algorithm well removes the phase ambiguity, and have almost same estimation performance compared with conventional one when there is not the phase ambiguity.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.12
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• pp.1572-1580
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• 1995

In this paper, a modified Chebyshev low-pass filter function is proposed. The modified Chebyshev filter function exhibits ripples diminishing toward .omega. = 0 in the passband. So, the modified filter function is realizable in the passive doubly-terminated ladder network for the order n even or odd, thus lending itself amenable to active RC or switched capacitor filters through the simulation techniques. Besides the passive doubly-terminated ladder realizability, lower pole-Q values of the modified function are accountable for improved phase and delay characteristics, as compared to classical function. We have designed the 6th order passive doubly-terminated network using the modified function. And then a continuous-time DDA(Differential Difference Amplifier) filter, which has no matching requirement, is realized by leap-frog simulation technique for fabrication. In the HSPICE simulation results, we confirmed that the designed continuous-time DDA filter characteristics are agreement with the passive filter.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.8
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• pp.1464-1469
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• 2008

A CMOS Gm-C filter with variable cutoff frequency applicable for using in the direct conversion receiver is designed. The designed filter comprises the CMOS differential transconductors, and the gm of the transconductor is controlled by the bias voltage. This configuration can compensate variant of the cutoff frequency which could be generated by external noises, and also be used in multiband receiver. As a results of HSPICE simulation, the control range of the cutoff frequency is $1.5MHz{\sim}3.5MHz$ and the gain control range is $-2.8dB{\sim}2.6dB$. The layout of the designed 5th-order Elliptic low-pass filter is performed to fabricate a chip using $2.5V-0.25{\mu}m$ CMOS processing parameter.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.12
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• pp.1227-1233
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• 2004

Air handling unit (AHU)'s air filter pressure difference is important for energy consumption and indoor air quality. Both energy Performance data and air filter differential pressure of AHU in real office buildings were monitored and analyzed to investigate quantitatively energy impact as dust buildup level on air filter grows. We also modeled and simulated CAV system using HVACSIM＋ program to examine the energy effect of dust buildup on filters. Through analysis of time series pressure drop data, the filter pressure difference rate has been increased due to cumulative supply air flow rate increase. As filter pressure drop increased to 1 inch water column, it is found that the supply air flow rate was decreased by 10%, the chilled water flow rate was increased by 5.9% and the pump energy consumption was increased to 5.9%.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.7
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• pp.827-835
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• 1999

In this paper, a dead reckoning navigation system for differential drive mobile robots is presented. The navigation system consists of two incremental encoders and a gyroscope. We have built a third order polynomial function for compensating the nonlinear scale factor errors of the gyroscope. We utilize an indirect Kalman filter that feeds back estimated errors to the main navigation system. Also, the observability of the filter is analyzed in order to systematically evaluate the filter's performance. Experimental results show that the proposed navigation system provides a reliable position and heading angle by mutually compensating the encoder and the gyroscope errors. The proposed filter also reduces the computational burden and enhances the navigation system's reliability. The observability analysis confirms the characteristics of inevitably unbounded position error growth in dead reckoning navigation systems.