Low-pass Notch Filter Research Articles

노치필터를 이용한 주파수 체배기 설계에 관한 연구

In this paper, we propose a frequency multiplier design using a notch filter. The notch filter is a filter that blocks the frequencies f1 and f2 around the center frequency f0 and passes the other frequencies. The notch filter can be classified into a low-pass notch filter and a high-pass notch filter. In this paper, we propose a filter using a highpass notch filter. The proposed filter is designed to have a 5.8㎓ (8㏈m) output signal and a maximum conversion gain of 8㏈ by inputting 2.9㎓ (0㏈m) of the input signal. This multiplier implements small wireless IoT, especially 5.8㎓ frequency band voice and image transmitter, IEEE802.11a and 5.8㎓ multiplier which is allocated to DRON control.

An Analog Front-End Chip With Self-Calibrated Input Impedance for Monitoring of Biosignals via Dry Electrode-Skin Interfaces

This paper demonstrates an input impedance boosting method that was developed for long-term monitoring of electroencephalography signals. An instrumentation amplifier was designed with a negative capacitance generation feedback (NCGFB) technique to cancel the adverse effects of input capacitances from electrode cables and printed circuit boards. The NCGFB boosts the measured impedance from below 40 M $\Omega $ to above 500 M $\Omega $ at 50 Hz when the equivalent capacitance at the inputs is up to 150 pF. The prototype chip includes an automatic calibration system to adaptively enhance the input impedance through on-chip test signal generation, measurement, and the automatic digital control of the NCGFB. Consisting of an instrumentation amplifier, a low-pass notch filter, and a variable gain amplifier in 130-nm CMOS technology, the signal path has a combined gain range of 66–93 dB with a total power consumption of 42 $\mu$ W. The front-end bandwidth covers 0.5–48 Hz, and its integrated input-referred noise over the bandwidth is 3.75 $\mu$ Vrms. The measured third-order harmonic distortion component is at least 57 dB below the fundamental signal level. A common-mode rejection ratio of 77.6 dB and a power supply rejection ratio of 74 dB were measured at 10 Hz. When activated, the auxiliary test signal generation and calibration circuits consume a power of 542 $\mu$ W.

A 5th order video band elliptic filter topology using OTRA based Fleischer Tow Biquad with MOS-C Realization

A new 5th order video band elliptic filter topology is presented. In video applications high order elliptic filters were used. The proposed 5th-order lowpass filter was simulated with PSPICE simulation program. The elliptic filter configuration consists of two cascade connected lowpass notch filters and a lowpass filter which is obtained using OTRA based Fleischer Tow biquad. After designing the 5th order video band elliptic filter topology, the MOS-C realization is obtained and used in PSPICE simulation.

A Novel Grid Synchronization PLL Method Based on Adaptive Low-Pass Notch Filter for Grid-Connected PCS

The amount of distributed energy resources (DERs) has increased constantly worldwide. The power ratings of DERs have become considerably high, as required by the new grid code requirement. To follow the grid code and optimize the function of grid-connected inverters based on DERs, a phase-locked loop (PLL) is essential for detecting the grid phase angle accurately when the grid voltage is polluted by harmonics and imbalance. This paper proposes a novel low-pass notch filter PLL (LPN-PLL) control strategy to synchronize with the true phase angle of the grid instead of using a conventional synchronous reference frame PLL (SRF-PLL), which requires a d-q-axis transformation of three-phase voltage and a proportional-integral controller. The proposed LPN-PLL is an upgraded version of the PLL method using the fast Fourier transform concept (FFT-PLL) which is robust to the harmonics and imbalance of the grid voltage. The proposed PLL algorithm was compared with conventional SRF-PLL and FFT-PLL and was implemented digitally using a digital signal processor TMS320F28335. A 10-kW three-phase grid-connected inverter was set, and a verification experiment was performed, showing the high performance and robustness of the proposal under low-voltage ride-through operation.

Integrated driving and readout circuits for orthogonal fluxgate sensor

This paper presents a CMOS integrated circuit (IC) for an orthogonal fluxgate sensor that is suitable for weak magnetic field measurement. The IC chip includes both driving and readout circuits. The driving circuit is able to deliver a pulse current up to 80 mA to drive the wires in the sensor core. The readout circuit employs a flux lock loop to accurately set the operating point of the sensor. A low-pass notch filter determines the bandwidth of the sensing system and rejects the 50-Hz interference. The measured total noise in the pass-band of 0.5-16 Hz is about 2.2 /spl mu/V. A minimum detectable magnetic field of 1.7/spl times/10/sup -9/ T without using the averaging has been achieved in the unshielded environment.

A CMOS Continuous-Time Low-Pass Notch Filter for EEG Systems

A CMOS OTA-C low-pass notch filter for EEG application is described. The pass-band covers four bands of brain wave and provides more than 65 dB attenuation for the 50 Hz power line interference. The OTA works in the weak inversion region and a low transconductance of 3 nA/V is achieved. The low transconductance enables using small capacitors in the OTA-C filter so that the filter is suitable for the multi-channel EEG integrated circuits. The measured results show the good performance of the filter for filtering the noise in acquired EEG signals.

Chebyshev Design of a Class Of FIR Filters With Frequency EquationConstraints

This paper considers the design of finite impulse response (FIR) filters with equation constraints in the frequency domain and proposes a design algorithm. The design problem is formulated as Chebyshev approximation subject to equation constraints. The optimal filter is proved to have a characteristic property that there exists a set of frequencies including extremal frequencies where the weighted error takes a maximum value, and constraint frequencies where the response takes a given magnitude. According to this property, an orthogonal projection-based Remez exchange algorithm is proposed to solve the constrained Chebyshev design problem. As its application, the algorithm is applied to the design of FIR lowpass filters and notch filters. Simulation examples demonstrate the effectiveness and good performance of the proposed algorithm.

A 0.5-mW passive telemetry IC for biomedical applications

A low-power, single-chip, one-channel, fully implantable microtransponder system for low-frequency biomedical sensor applications is described. The circuit is powered by an external RF source at 27/40 MHz. No battery is required. Wireless communication with external monitoring units is realized by absorption modulation. As the radiated power received by a small coil can be as low as a few milliwatts, the data acquisition/transmission system has been optimized for low power consumption. The system has been integrated in a 2-/spl mu/m 40-V BiCMOS technology. It includes a low-offset amplifier, a low-pass notch filter, an A/D converter, a voltage doubler/rectifier, as well as a low-power voltage regulator. The implemented switched-capacitor amplifier features 45-/spl mu/V offset and an integrated noise of 21 /spl mu/V for a bandwidth of 30 Hz while consuming less than 30 /spl mu/W power. The digitized sensor data are transmitted as low duty-cycle PPM-AM signals with a rate of 1 kBd. The entire system, including the 1.6-k/spl Omega/ bridge sensor, consumes only 520 /spl mu/W, which makes it well suited for long-term monitoring of biomedical signals.

Versatile architecture for current-mode biquadratic filters in CMOS technology

A versatile programmable current-mode architecture for realising a given second order biquadratic filter is proposed. The architecture consists of programmed interconnections of three basic building blocks: transconductance cells, buffered current mirrors and current buffer cells. In the case of stand-alone IC chips, transfer function coefficients are set through external control voltages, and in the case of an analogue/digital mixed mode VLSI environment, through internal control voltages. Designs for a video-band lowpass notch filter and a high-frequency bandpass filter realisable using 1.2 micron CMOS technology and consuming, respectively, 1.96 mW and 2.36 mW of power, are presented as illustrations. It is expected that optimised designs will lead to reduced power consumption.

A low-pass notch filter for bioelectric signals.

Many bioelectric signals have relatively low-frequency content, but measurement devices are susceptible to power-line interference. The Type II Chebyshev low-pass filter can simultaneously perform the required low-pass filtering and removal of the narrowband interference. This filter has transfer-function zeros which result in zero gain (- infinity dB) at specific 'null' frequencies. A procedure for the low-pass filter design makes the first null frequency a design parameter so that the notch can occur at the interference frequency. >

The Pole-Zero Locations of Trimmed Distributed RC Active Notch Filters

The application of trimmed thick-film distributed resistance-capacitance (RC) networks to the construction of low pass notch filters is described. It is shown that the pole-zero positions of a trimmed distributed low pass filter with zeros in the stop band may be evaluated interactively by curve fitting its frequency response. High pass notch and rand reject filters can also be constructed and their pole-zero locations evaluated using the same approach.