• ETRI Journal
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• v.42 no.4
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• pp.534-548
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• 2020

This study presents a new architecture for a field programmable analog array (FPAA) for use in low-frequency applications, and a generalized circuit realization method for the implementation of nth-order elliptic filters. The proposed designs of both the FPAA and elliptic filters are based on the operational transconductance amplifier (OTA) used in implementing OTA-C filters for biopotential signal processing. The proposed FPAA architecture has a flexible, expandable structure with direct connections between configurable analog blocks (CABs) that eliminates the use of switches. The generalized elliptic filter circuit realization provides a simplified, direct synthetic method for an OTA-C symmetric balanced structure for even/odd-nth-order low-pass filters (LPFs) and notch filters with minimum number of components, using grounded capacitors. The filters are mapped on the FPAA, and both architectures are validated with simulations in LTspice using 90-nm complementary metal-oxide semiconductor (CMOS) technology. Both proposed FPAA and filters generalized synthetic method achieve simple, flexible, low-power designs for implementation of biopotential signal processing systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.8
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• pp.1753-1758
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• 2012

This paper introduces analog FIR filters based on a distributed amplifier and analyzes the proposed filter's characteristics. A simple design method of an analog FIR filter based on the digital filter design technique is also introduced. The proposed analog FIR filters are a moving average(MA) and a comb type filters with no multiplier. This simple structures of the proposed filters may enable to operate at multi-GHz frequency range and applicable to combine a filter and an amplifier of RF system. The proposed analog FIR filters were implemented with standard $0.18{\mu}m$ CMOS technology. The designed GHz analog FIR filters are simulated by Cadence Spectre and compared to the results of digital FIR filters obtained from MATLAB simulations. From the simulation results, the characteristics of the proposed analog FIR filters are fairly well matched with those of digital FIR filters.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.5
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• pp.315-322
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• 1986

In this paper, we have studied on the IIR digital filters design using Elliptic functions. In process of transformation to digital fouctions from analos Elliptic functions, Bilinear z transformation method has been silized. Designing of digital filter using the Bilinear z transformation the problems of aliasing can be avoidedm whereas the frequency distrotion is generated. The transformation form analog function to digital function is not equal in the region of the cut off frequency response caused by this effect. Avoiding the problem of this effect, we have used proewarping method. Finally, the magnitude characteristics of digital filters are compared with its of analog filters by computer simulation. The results have shown that the magnitude characteristics of digital filters by the prewarping method have made more remarkable improvement than its of analog filters.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.6
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• pp.292-298
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• 2006

Because of the high cost for the active power filter, passive filters have been widly used to eliminate harmonic currents of nonlinear load and can also improve the power factor. They are not often optimal filters because the passive filters are designed under the fixed load conditions. In this paper we proposed the method which only the necessary harmonic filters are operated by detecting the various harmonic current components. We presents the new control method of passive filter selection type with the relay control circuit which is consist of analog GIC, comparater, flip-flop and etc. By the experimental results using the proposed system for the rectifier load, we concluded that the researched method is cost effective and the performance is better than the passive filter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.1
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• pp.1-9
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• 1994

In general, when IIR digital filter are designed from analog filters, the bilinera transformation and the impluse invariant tramsformation are commonly used. It is known, however, that high frequency response of digital filters designed by these transformations can not be well approximated to the sampled analog signals. In this paper, the symbol pulse invariant transformation is analyzed theoretically so that the symbol pulse invariant transformation which was originally application to a rectangular pulse is newly applied to double rate pulse signals and generic shape pulse signals. Also, the relation of spectra between a transfer function of digital filter and one of analog filter is considered. Further, we apply to design the digital high pass filters using the symbol pulse invariant transformation method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.7
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• pp.1424-1428
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• 2004

In this paper, CMOS analog filters for use in the Analog front End of digital subscriber loop(DSL) chip set are proposed. Designed filters contain receiver continuous-time filters which are composed of lowpass and highpass functions. And their cutoff frequency are 138H1z and 1.1MHz respectively. A low-voltage gm-c integrator is improved and used to design filters. Desisned filters are verified by HSPICE simulation with the 0.25${\mu}m$ CMOS n-well parameter.

• Proceedings of the IEEK Conference
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• summer
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• pp.199-203
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• 2004

In this paper, we only describe the digital block of two-channel 18-bit analog-to-digital (A/D) converter employing sigma-delta method and xl28 decimation. The device contains two fourth comb filters with 1-bit input from sigma­delta modulator. each followed by a digital half band FIR(Finite Impulse Response) filters. The external analog sigma-delta modulators are sampled at 6.144MHz and the digital words are output at 48kHz. The fourth-order comb filter has designed 3 types of ways for optimal power consumption and signal-to-noise ratio. The following 3 digital filters are designed with 12tap, 22tap and 116tap to meet the specification. These filters eliminate images of the base band audio signal that exist at multiples of the input sample rate. We also designed these filters with 8bit and 16bit filter coefficient to analysis signal-to-noise ratio and hardware complexity. It also included digital output interface block for I2S serial data protocol, test circuit and internal input vector generator. It is fabricated with 0.35um HYNIX standard CMOS cell library with 3.3V supply voltage and the chip size is 2000um by 2000um. The function and the performance have been verified using Verilog XL logic simulator and Matlab tool.

• ETRI Journal
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• v.32 no.6
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• pp.911-920
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• 2010

This paper presents a method of designing hybrid analog/asymmetrical square-root (SR) FIR filters. In addition to the conventional frequency domain constraints, the proposed method considers time-domain constraints as well, including the inter-symbol interference (ISI) and the opening of the eye pattern at the receiver output. This paper also reviews a systematic way to find the discrete-time equivalence of analog parts in a band-limited digital communication system. Thus, a phase equalizer can be easily realized to compensate for the nonlinear phase responses of the analog components. With the hybrid analog/SR FIR filter co-design, examples show that using the proposed method can result in a more robust ISI performance in the presence of the receiver clock jitter.

• The Journal of Korea Robotics Society
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• v.2 no.3
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• pp.205-211
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• 2007

In this paper, the prototype of surface EMG (ElectroMyoGram) sensor is developed for the robotic rehabilitation applications, and the developed sensor is composed of the electrodes, analog signal amplifiers, analog filters, ADC (analog to digital converter), and DSP (digital signal processor) for coding the application example. Since the raw EMG signal is very low voltage, it is amplified by about one thousand times. The artifacts of amplified EMG signal are removed by using the band-pass filter. Also, the processed analog EMG signal is converted into the digital form by using ADC embedded in DSP. The developed sensor shows approximately the linear characteristics between the amplitude values of the sensor signals measured from the biceps brachii of human upper arm and the joint angles of human elbow. Finally, to show the performance of the developed EMG sensor, we suggest the application example about the real-time human elbow motion acquisition by using the developed sensor.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.123-132
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• 1987

In this paper, we studied on the design of elliptic digital filters using the bilinear z transformation method, and proposed a design procedure satisfying prescribed specifications. The magnitude characteristics of digital filters are compared with its of analog filiters by computer simulation. Finaly we considered the quantization effects of digital filters. In cascader realization of fixed-point digital filters under dynamic range constraints, the outpout noise for IIR digital filters depends on the pole-zero pairing and ordering of the second order sections. Therfore an optmization procedure to finding a good ordering and pairing is very desirable. Thus, we proposed a sub-optimization procedure for finding "near optimal" solution.