Showing papers on "Root-raised-cosine filter published in 2023"

A Time-Mode PWM 1st Order Low-Pass Filter

Abstract: In this work, a first-order low-pass filter is proposed as suitable for time-mode PWM signal processing. In time-mode PWM signal processing, the pulse width of a rectangular pulse is the processing variable. The filter is constructed using basic time-mode building blocks such as time registers and time adders and so it is characterized by low complexity which can lead to the modular and versatile design of higher-order filters. All the building blocks of the filter were designed and verified in a TSMC 65 nm technology process. The sampling frequency was 5 MHz, the gain of the filter at low frequencies was at −0.016 dB, the cut-off frequency was 1.2323 MHz, and the power consumption was around 59.1 μW.

Second order universal filter using voltage follower topology

Abstract: Abstract In this paper, a voltage mode multi input single output second order universal filter based on the voltage follower concept is proposed. The MISO filter offers low-pass, band-pass, high-pass, all-pass and band-stop filters which is digital selecting by the input. The filter design consists of positive feedback and feed forwards path to implement a universal filter. The positive feedback is used to increase the quality factor of the filter. The feed forwards path is necessary to create zeros for the band-stop and high-pass filter. The proposed filter has many advantages such as an electronically tunable filter response, low power consumption and area. The performance of the proposed design has been tested using CMOS 130nm process technology.

Filtering Eye-Tracking Data From an EyeLink 1000: Comparing Heuristic, Savitzky-Golay, IIR and FIR Digital Filters

Abstract: In a previous report (Raju et al.,2023) we concluded that, if the goal was to preserve events such as saccades, microsaccades, and smooth pursuit in eye-tracking recordings, data with sine wave frequencies less than 100 Hz (-3db) were the signal and data above 100 Hz were noise. We compare 5 filters in their ability to preserve signal and remove noise. Specifically, we compared the proprietary STD and EXTRA heuristic filters provided by our EyeLink 1000 (SR-Research, Ottawa, Canada), a Savitzky-Golay (SG) filter, an infinite impulse response (IIR) filter (low-pass Butterworth), and a finite impulse filter (FIR). For each of the non-heuristic filters, we systematically searched for optimal parameters. Both the IIR and the FIR filters were zero-phase filters. Mean frequency response profiles and amplitude spectra for all 5 filters are provided. In addition, we examined the effect of our filters on a noisy recording. Our FIR filter had the sharpest roll-off of any filter. Therefore, it maintained the signal and removed noise more effectively than any other filter. On this basis, we recommend the use of our FIR filter. Several reports have shown that filtering increased the temporal autocorrelation of a signal. To address this, the present filters were also evaluated in terms of autocorrelation (specifically the first 3 lags). Of all our filters, the STD filter introduced the least amount of autocorrelation.

Design and Analysis of CIC Decimation Filter Using Redundant Number System

Abstract: The multirate transformation is a frequently used method for decimation and interpolation in real-time digital signal processing. In wireless applications, comb-based decimation filters are used because of their high alias elimination and low complexity. A symmetrical FIR filter, namely a cascaded integrator-comb (CIC) filter, can be utilized as a decimation filter. Since this filter does not have a multiplier, it requires fewer hardware resources and has a higher speed than other decimation filters. The main considerations in design objectives for current digital signal processing (DSP) applications are optimization of power, speed and hardware resources. The redundant number system is used in digital systems to reduce computational load, and this efficiency can then be further improved by modifying the architecture at the circuit level. Thus, the signed digit-based FIR filter is proposed as a compensation filter that reduces the passband droop and increases the attenuation in the folding band. Based on the proposed compensation filter with CIC filter design, a reduction in passband droop of 17.27 $$\%$$ and improvement in attenuation in the folding band of 12.29 $$\%$$ are achieved in comparison with the existing structure. In addition, the simulation results show a decrease in LUTs utilized of 10.44 $$\%$$ in comparison with the existing design.

Matched-Filter Design to Improve Self-Interference Cancellation in Full-Duplex Communication Systems

Abstract: A new method for capacity and spectral efficiency increases is a full-duplex communication, where sending and receiving are done simultaneously. Hence, severe interference leaked from the transmitter to the receiver, which can disrupt the system’s operation completely. For interference reduction, the transceiver tries to estimate the interfering symbols to remove their effects. A typical method is to use the Hammerstein model. In this method, nonlinear power amplifier (PA) and multipath channel are modeled with a successive nonlinear system and a finite impulse response filter. Then, the model parameters are adjusted, and interference symbols are estimated from the transmitted symbols. In the Hammerstein method, the interference symbols are estimated directly from the transmitted symbols. But practically, the transmitted symbols first pass through the pulse-shaping filter and become a signal. Then, this signal passes through the nonlinear PA and communication channel. Finally, the received signal is filtered by the matched filter (MF) at the receiver and converted to the symbols again. In this procedure, the amplifier and the communication channel affect the transmitted signal directly and distort transmitted symbols indirectly. Therefore, in the practical situation, when we consider the transmitter’s pulse-shaping filter and the receiver’s MF, the estimated symbols with the Hammerstein method are erroneous. To solve this problem, a new MF at the receiver is proposed and adjusted according to the interfering signal. We have shown that this method is far better than the Hammerstein method.