scispace - formally typeset
Search or ask a question

Showing papers on "Low-pass filter published in 2012"


Journal ArticleDOI
TL;DR: The LLCL filter as mentioned in this paper inserts a small inductor in the branch loop of the capacitor in the traditional LCL filter to compose a series resonant circuit at the switching frequency, which attenuates the switching-frequency current ripple components much better than an LCL filtering.
Abstract: This paper presents a new topology of higher order power filter for grid-tied voltage-source inverters, named the LLCL filter, which inserts a small inductor in the branch loop of the capacitor in the traditional LCL filter to compose a series resonant circuit at the switching frequency. Particularly, it can attenuate the switching-frequency current ripple components much better than an LCL filter, leading to a decrease in the total inductance and volume. Furthermore, by decreasing the inductance of a grid-side inductor, it raises the characteristic resonance frequency, which is beneficial to the inverter system control. The parameter design criteria of the proposed LLCL filter is also introduced. The comparative analysis and discussions regarding the traditional LCL filter and the proposed LLCL filter have been presented and evaluated through experiment on a 1.8-kW-single-phase grid-tied inverter prototype.

350 citations


Proceedings ArticleDOI
05 May 2012
TL;DR: The 1 € filter ("one Euro filter") is a simple algorithm to filter noisy signals for high precision and responsiveness using a first order low-pass filter with an adaptive cutoff frequency.
Abstract: The 1 € filter ("one Euro filter") is a simple algorithm to filter noisy signals for high precision and responsiveness. It uses a first order low-pass filter with an adaptive cutoff frequency: at low speeds, a low cutoff stabilizes the signal by reducing jitter, but as speed increases, the cutoff is increased to reduce lag. The algorithm is easy to implement, uses very few resources, and with two easily understood parameters, it is easy to tune. In a comparison with other filters, the 1 € filter has less lag using a reference amount of jitter reduction.

264 citations


Journal ArticleDOI
TL;DR: In this paper, a hybrid active filter is proposed for mitigating the line-side harmonic currents of a three-phase 12-pulse diode rectifier used as the front end of a medium-voltage high-power motor drive.
Abstract: This paper describes a hybrid active filter intended for mitigating the line-side harmonic currents of a three-phase 12-pulse diode rectifier used as the front end of a medium-voltage high-power motor drive. This hybrid filter is characterized by series connection of a simple LC filter and a small-rated active filter. This circuit configuration brings low cost, small size, and light weight to the hybrid filter. A three-phase experimental system rated at 400 V and 15 kW is designed, constructed, and tested, which is a downscaled model of the medium-voltage motor drive system. In this experiment, the LC filter is tuned to the 11th-harmonic frequency, and the active filter is based on a three-level neutral-point-clamped pulsewidth modulation converter (NPC PWM) with a dc capacitor voltage as low as 28 V. This hybrid filter is connected on either first or fourth winding of a line-frequency transformer with a first Δ-winding voltage of 400 V in the primary, and a second Δ-winding voltage of 220 V, a third Y-winding voltage of 220 V, and a fourth Δ-winding voltage of 400 V in the secondary. Experimental results show that the hybrid filter performs satisfactory filtering in a range from no-load to full-load conditions.

209 citations


Journal ArticleDOI
TL;DR: A widely tunable 4th order BPF based on the subtraction of two 2nd order 4-path passive-mixer filters with slightly different center frequencies is proposed.
Abstract: A widely tunable 4th order BPF based on the subtraction of two 2nd order 4-path passive-mixer filters with slightly different center frequencies is proposed. The center frequency of each 4-path filter is slightly shifted relative to its clock frequency (one upward and the other one downward) by agm-C technique. Capacitive splitting of the input signal is used to reduce the mutual loading of the two 4-path BPFs and increase their quality factors. The filter is tunable from 0.4 GHz to 1.2 GHz with approximately constant bandwidth of 21 MHz. The in-band 1-dB compression point of the filter is -4.4 dBm while the in-band IIP3 of the filter is +9 dBm and the out-of-band IIP3 is + 29 dBm (Δf=+50 MHz). The ultimate rejection of the filter is >; 55 dB and the NF of the filter is 10 dB. The static and dynamic current consumption of the filter are 2.8 mA from 2.5 V and 12 mA from 1.2 V, respectively (at 1 GHz). The LO leakage power to the input port is <; - 60 dBm. The filter has been fabricated in CMOS LP 65 nm technology and the active area is 0.127 mm2.

131 citations


Book
06 Dec 2012
TL;DR: Acoustic Signals of Animals: Recording, Field Measurements, Analysis and Description finds application of Filters in Bioacoustics, Digital Signal Analysis, Editing, and Synthesis, and Properties of Various Analog Filters and Antialiasing and Antiimaging Filters.
Abstract: Chapter 1 Acoustic Signals of Animals: Recording, Field Measurements, Analysis and Description H. C. Gerhardt 1 Introduction 2 Field Recordings and Measurements 2.1 Equipment 2.2 On-Site Measurements 2.3 Signal Amplitude, Directionality, and Background Noise Levels 2.4 Patterns of Sound Propagation in Natural Habitats 3 Laboratory Analysis of Animal Sounds 3.1 Terminology 3.2 Temporal and Spectral Analysis: Some General Principles 4 Examples of Descriptions and Analyses 4.1 Temporal Properties of Pulsatile Calls 4.2 Amplitude-Time Envelopes 4.3 Relationships between Fine-Scale Temporal and Spectral Properties 4.4 Spectrally Complex Calls 5 Summary References.- Chapter 2 Digital Signal Acquisition and Representation M. Clements 1 Introduction 2 Digital Signal Processing 2.1 Major Applications of DSP 2.2 Definition of Digital Systems 2.3 Difference Equations 3 Digital Filter Frequency Response 3.1 Unit-Sample Response Characterization 3.2 Frequency-Domain Interpretation of Systems 3.3 Frequency-Domain Interpretation of Signals 4 Conversion Between Analog and Digital Data Forms 4.1 The Sampling Theorem 4.2 Signal Recovery by Filtering 4.3 Fourier Transform Relations 4.4 Effects of Sampling Rates 4.5 Reconstruction 5 Fundamental Digital Processing Techniques 5.1 Power Spectra 5.2 Time and Frequency Resolution 5.3 Windows 5.4 Spectral Smoothing 5.5 The Discrete Fourier Transform 5.6 Correlation 5.7 Autocorrelation 5.8 Cross-correlation 5.9 Spectrograms 6 An Intoduction to Some Advanced Topics 6.1 Digital Filtering 6.2 Linear Prediction 6.3 Homomorphic Analysis 7 Summary.- Chapter 3 Digital Signal Analysis, Editing, and Synthesis K. Beeman 1 Introduction 2 Temporal and Spectral Measurements 3 Time-Varying Amplitude Analysis 3.1 Amplitude Envelopes 3.2 Gate Functions 4 Spectral Analysis 4.1 Power Spectrum Features 4.2 Measuring Similarity Among Power Spectra 4.3 Other Spectral Analysis Techniques 5 Spectrographic Analysis 5.1 Spectrogram Generation 5.2 Spectrogram Display 5.3 Spectrogram Parameter Measurements 6 Classification of Naturally Occurring Animal Sounds 6.1 Properties of Ideal Signals 6.1.1 Periodicity 6.1.2 Amplitude Modulation 6.1.3 Frequency Modulation 6.1.4 Biologically Relevant Sound Types 7 Time-varying Frequency Analysis 7.1 Deriving Spectral Contours 7.2 Sound-similarity Comparison 8 Digital Sound Synthesis 8.1 Editing 8.2 Arithmetic Manipulation and Generation of Sound 8.3 Synthesis Models 8.3.1 Tonal Model 8.4 Sources of and A Functions 8.4.1 Mathematically Based Functions 8.4.2 Functions Derived from Natural Sounds 9 Sound Manipulation and Generation Techniques 9.1 Duration Scaling 9.2 Amplitude-Envelope Manipulations 9.3 Spectral Manipulations 9.3.1 Frequency Shifting and Scaling 9.3.2 Frequency Modulation 9.4 Synthesis of Biological Sound Types 9.4.1 Tonal and Polytonal Signals 9.4.2 Pulse-Repetition Signals 9.4.3 Harmonic Signals 9.4.4 Noisy Signals 9.5 Miscellaneous Synthesis Topics 9.5.1 Template Sounds 9.5.2 Noise Removal 10 Summary References.- Chapter 4 Application of Filters in Bioacoustics P. K. Stoddard 1 Introduction 2 General Uses of Filters and Some Cautions 3 Anatomy and Performance of a Filter 4 Properties of Various Analog Filters 5 Antialiasing and Antiimaging Filters 5.1 A/D Conversion Requires an Analog Lowpass Filter 5.2 Choosing an Antialiasing Filter 5.3 D/A Conversion also Requires an Analog Lowpass Filter 5.4 Analog Filters: Passive Versus Active Components 6 Analog Versus Digital Filters

98 citations


Book
08 Apr 2012
TL;DR: Bergman as mentioned in this paper proposed a linear time invariant system for the measurement of wavelet parameters from digital seismograms, based on the RC filter and the digital anti-alias filter.
Abstract: Preface to the revised second edition. Preface to the first edition. Foreword E. Bergman. 1. Introduction. 2. RC Filter. 3. General linear time invariant systems. 4. The seismometer. 5. The sampling process. 6. Analog-to-digital conversion. 7. From infinitely continuous to finite discrete. 8. The digital anti-alias filter. 9. Inverse and simulation filtering of digital seismograms. 10. The measurement of wavelet parameters from digital seismograms. References. Appendix: Solution to problems. Index.

96 citations


Journal ArticleDOI
TL;DR: In this article, a TE011Ka-band tunable filter with a stable and continuous tuning performance is presented by cascading six-pole pseudo-low-pass and pseudo-high-pass tunable filters.
Abstract: A TE011Ka-band tunable filter with a stable and continuous tuning performance is presented in this paper. Both bandwidth and center-frequency tunability are demonstrated by cascading six-pole pseudo-low-pass and pseudo-high-pass tunable filters. A novel mode-splitter resonator and coupling configuration enabling cross-coupled planar TE011 filter realization is introduced in this paper. The concept can be applied to back-to-back coupled TE011 resonators as well. The filter design is verified through fabrication of multiple tunable filters that demonstrates 500 MHz of tuning range with a stable RF tuning performance.

94 citations


Journal ArticleDOI
TL;DR: This work considers here the case where a filter is constructed using two fractional-order elements of different orders @a and @b, and the design equations for the filter are generalized taking into consideration stability constraints.

85 citations


Journal ArticleDOI
TL;DR: In this article, a new type of bandstop-to-all-pass reconfigurable filter is developed and the relationship between resonator quality factor, filter bandwidth, and the all-pass response state is shown for the first time.
Abstract: The theory of a new type of bandstop-to-all-pass reconfigurable filter is developed in this work. A bandstop filter structure with both source-to-load and inter-resonator coupling is implemented. The synthesis equations are manipulated such that the signals in the filter's resonators and source-to-load transmission line can be made to constructively or destructively interfere at the output port through tuning of the resonant frequency of the filter's resonators. The relationship between resonator quality factor, filter bandwidth, and the all-pass response state is shown for the first time. The theory is proven through fabrication of a bandstop-to-all-pass filter with resonator unloaded quality factors greater than 500. Measured results show that the filter can continuously tune from insertion loss of 2.1 dB in the all-pass state to insertion loss of 69 dB in the bandstop state at the center frequency of the filter. Analog tuning of the attenuation level is also shown. The capability to switch from an all-pass to a variable-attenuation bandstop response enables a spectrally aware system to operate over wide bandwidths when interference levels are low and to dynamically add bandstop responses when interference affects its performance or signal equalization is required.

84 citations


Journal ArticleDOI
TL;DR: Experimental results are presented that demonstrate a single passband, flat-top radio-frequency filter response without free spectral range limitations, along with the capability of tuning the center frequency and filter bandwidth independently.
Abstract: A new and simple structure for a single passband microwave photonic filter is presented. It is based on using an electro-optical phase modulator and a tunable optical filter and only requires a single wavelength source and a single photodetector. Experimental results are presented that demonstrate a single passband, flat-top radio-frequency filter response without free spectral range limitations, along with the capability of tuning the center frequency and filter bandwidth independently.

83 citations


Journal ArticleDOI
TL;DR: In this article, a switchable microwave photonic filter that can be readily switched between a bandpass filter and a notch filter is presented. But the switching of the filter function is simply and conveniently obtained by changing the dc bias to the dual-drive Mach-Zehnder modulator.
Abstract: A new structure that realizes a switchable microwave photonic filter, which can be readily switched between a bandpass filter and a notch filter, is presented. It is based on optical processing the sidebands of the RF-modulated signal that is obtained after a dual-drive Mach–Zehnder modulator (DDMZM), using stimulated Brillouin scattering (SBS) effects. Switching of the filter function is simply and conveniently obtained by changing the dc bias to the DDMZM. In addition, the center frequency of the switchable filter can be tuned over a wide frequency range. A detailed analysis and simulation of the DDMZM operation in conjunction with the SBS technique is presented in order to obtain the required optimum bias conditions for the DDMZM for realizing the switching action between the single-bandpass filter and the notch filter and also to select the optimum pump power for the SBS operation. Experimental results demonstrate the ability of this structure to switch between a high-resolution bandpass filter and a high-resolution notch filter, with Q values around 400–500, and the ability to operate over a frequency range of 2–20 GHz.

Journal ArticleDOI
TL;DR: In this article, a common-mode filter is proposed to suppress the commonmode noise and its resulting electromagnetic interference (EMI) emission from the attached cable by using a pair of distributed signal lines on the top of a mushroom-like structure.
Abstract: A compact and wideband common-mode filter is newly proposed to embed in a cable-attached printed circuit board (PCB) or packages for the suppression of the common-mode noise and its resulting electromagnetic interference (EMI) emission from the attached cable. The proposed filter consists of a pair of distributed signal lines on the top of a mushroom-like structure. Owing to its symmetry, an equivalent circuit model is developed and applied efficiently for this filter design. As an example, a filter prototype is designed and fabricated on a multilayer PCB. The filter prototype shows that it can greatly reduce the common-mode noise over 10 dB from 1.65 to 5.2 GHz. In addition, the corresponding fractional bandwidth is over 100% while the electrical size of the prototype is only 0.11 × 0.11 λg, where λg is the wavelength of the central frequency of its stopband. Also in the time domain, this filter prototype can reduce over 60% of the unintended noise. More importantly, the differential-signal integrity, in terms of the insertion loss in the frequency domain and the eye diagram in the time domain, is maintained up to 7 GHz. To the best of our knowledge, it is the first embedded common-mode filter proposed for gigahertz differential signals with such a large bandwidth and the most compact size. To further demonstrate the ability of the filter to suppress the common-mode current on the attached cable and the corresponding EMI emission, a test board design is also introduced and realized. From the experimental results related to this test board, a 10-dB suppression on average is indeed achieved.

Patent
04 May 2012
TL;DR: In this article, a single-photon receiver and a method for detecting a singlephoton are presented, which comprises a SPAD that receives a gating signal having a fundamental frequency in the 100 MHz to multiple GHz range, and a two-stage frequency filter for filtering the output of the SPAD, wherein the filter has: (1) a notch filter response at the fundamental frequency; and (2) a low-pass filter response whose cutoff frequency is less than the first harmonic of the fundamental value.
Abstract: A single-photon receiver and method for detecting a single-photon are presented. The receiver comprises a SPAD that receives a gating signal having a fundamental frequency in the 100 MHz to multiple GHz range. The receiver further comprises a two-stage frequency filter for filtering the output of the SPAD, wherein the filter has: (1) a notch filter response at the fundamental frequency; and (2) a low-pass filter response whose cutoff frequency is less than the first harmonic of the fundamental frequency. As a result, the frequency filter removes substantially all the frequency components in the SPAD output without significant degradation of the signal quality but with reduced complexity, cost, and footprint requirement relative to receivers in the prior art.

Journal ArticleDOI
TL;DR: In this paper, a continuously tunable lumped bandpass filter is implemented in a third-order coupled resonator configuration, which is fabricated on Borosilicate glass substrate using a surface micromachining technology that offers hightunable passive components.
Abstract: This paper reports a continuously tunable lumped bandpass filter implemented in a third-order coupled resonator configuration. The filter is fabricated on a Borosilicate glass substrate using a surface micromachining technology that offers hightunable passive components. Continuous electrostatic tuning is achieved using three tunable capacitor banks, each consisting of one continuously tunable capacitor and three switched capacitors with pull-in voltage of less than 40 V. The center frequency of the filter is tuned from 1 GHz down to 600 MHz while maintaining a 3-dB bandwidth of 13%-14% and insertion loss of less than 4 dB. The maximum group delay is less than 10 ns across the entire tuning range. The temperature stability of the center frequency from -50°C to 50°C is better than 2%. The measured tuning speed of the filter is better than 80 s, and the is better than 20 dBm, which are in good agreement with simulations. The filter occupies a small size of less than 1.5 cm × 1.1 cm. The implemented filter shows the highest performance amongst the fully integrated microelectromechanical systems filters operating at sub-gigahertz range.

Journal ArticleDOI
TL;DR: In this article, the properties of tunable wavelength pi'n/pin filters based on a-SiC:H multilayered stacked cells are studied both experimentally and theoretically.
Abstract: Characteristics of tunable wavelength pi'n/pin filters based on a-SiC:H multilayered stacked cells are studied both experimentally and theoretically. Results show that the device combines the demultiplexing operation with the simultaneous photodetection and self amplification of the signal. An algorithm to decode the multiplex signal is established. A capacitive active band-pass filter model is presented and supported by an electrical simulation of the state variable filter circuit. Experimental and simulated results show that the device acts as a state variable filter. It combines the properties of active high-pass and low-pass filter sections into a capacitive active band-pass filter using a changing capacitance to control the power delivered to the load.

Journal ArticleDOI
TL;DR: In this paper, the authors presented a new methodology for the synthesis of tunable patch filters, which helps the designer to perform a theoretical analysis of the filter through a coupling matrix that includes the effect of tuning elements used to tune the filter.
Abstract: A new methodology for the synthesis of tunable patch filters is presented. The methodology helps the designer to perform a theoretical analysis of the filter through a coupling matrix that includes the effect of the tuning elements used to tune the filter. This general methodology accounts for any tuning parameter desired and was applied to the design of a tunable dual-mode patch filter with independent control of center frequency and bandwidth (BW). The bandpass filter uses a single triangular resonator with two etched slots that split the fundamental degenerate modes and form the filter passband. Varactor diodes assembled across the slots are used to vary the frequency of each degenerate fundamental mode independently, which is feasible due to the nature of the coupling scheme of the filter. The varactor diode model used in simulations, their assembling, the dc bias configuration, and measured results are presented. The theory results are compared to the simulations and to measurements showing a very good agreement and validating the proposed methodology. The fabricated filter presents an elliptic response with 20% of center frequency tuning range around 3.2 GHz and a fractional BW variation from 4% to 12% with low insertion loss and high power handling with a 1-dB compression point higher than .

Journal ArticleDOI
TL;DR: In this article, a simple feedback sensor capable of high-resolution average inductor current sensing using two analog comparators and an analog low-pass filter is proposed, which can be used to reduce the complexity of voltage A/D converters.
Abstract: Current-mode control in digitally controlled switched-mode power supplies typically requires analog-to-digital (A/D) conversion of at least two signals, voltage, and current. The complexity of voltage A/D converters can be reduced using window A/D techniques. In conventional current A/D conversion, however, relatively high resolution is required over a wide range of signals, which results in increased complexity, power consumption, and cost of the controller. This paper proposes a very simple feedback sensor capable of high-resolution average inductor current sensing using two analog comparators and an analog low-pass filter. The approach requires very few external components and employs minimal digital hardware resources. A dynamic model and performance of the average inductor current sensor are experimentally verified on a 12-V input, 19-V output, 50-W boost converter prototype. The applicability of the proposed sensor is demonstrated in a digitally controlled 400-W, 400-V output Boost power factor preregulator.

Journal ArticleDOI
TL;DR: In this article, a lumped-element low-temperature co-fired ceramic (LTCC) bandstop filter with low-Q resonators has been designed and measured, and the measurement showed 60-dB attenuation level at the center frequency.
Abstract: In this paper, we show a new absorptive banstop filter topology that is capable of creating large attenuation using low-Q small-size resonators. In addition, the implementation of a lumped-element absorptive bandstop filter is shown for the first time. Compared with the conventional absorptive filter structure, the new absorptive filter structure is smaller in size because there is no quarter-wavelength transmission line between two resonators and the resonators are lumped elements. For verification of the new topology, a lumped-element low-temperature co-fired ceramic (LTCC) bandstop filter with low-Q resonators has been designed and measured. Theory, simulation, and measurement showed good agreement between them, and the measurement showed 60-dB attenuation level at the center frequency. This attenuation level of the absorptive bandstop filter is 50 dB larger than the one obtained from the reflective bandstop filter with the same Q-factor and bandwidth. The small size and absorptive nature of the filter allow us to cascade the filters to create many different filter responses. It is shown that the lumped-element implementation makes the filter very amenable to realization of higher order responses in small form factors.

Journal ArticleDOI
TL;DR: A novel approach to impulse noise reduction in color image by applying the quaternion unit transform theory, an efficient filter that can switch between the vector median filter (VMF) and the identity filter (no filtering operation) is proposed.

Patent
Nadim Khlat1
30 Nov 2012
TL;DR: In this paper, the RF filter is coupled to receive a pulsed output voltage from the RF switching converter and a supply voltage from a low-drop out (LDO) regulation circuit.
Abstract: This disclosure relates to radio frequency (RF) power converters and methods of operating the same. In one embodiment, an RF power converter includes an RF switching converter, a low-drop out (LDO) regulation circuit, and an RF filter. The RF filter is coupled to receive a pulsed output voltage from the RF switching converter and a supply voltage from the LDO regulation circuit. The RF filter is operable to alternate between a first RF filter topology and a second RF filter topology. In the first RF filter topology, the RF filter is configured to convert the pulsed output voltage from a switching circuit into the supply voltage. The RF filter in the second RF filter topology is configured to filter the supply voltage from the LDO regulation circuit to reduce a ripple variation in a supply voltage level of the supply voltage. As such, the RF filter provides greater versatility.

Journal ArticleDOI
TL;DR: In this paper, a microstrip lowpass filter with compact size and an ultra-wide stopband is proposed, which can suppress the sixteenth harmonic response referred to a suppression degree of 15'dB.
Abstract: A new microstrip lowpass filter with compact size and an ultra-wide stopband is proposed. To achieve compact size and ultra-wide band rejection, both triangular patch resonators and radial patch resonators are introduced in the filter. To reduce the circuit size of the filter further, meander transmission lines are also adopted in the design. A demonstration filter with 3 dB cutoff frequency at 1 GHz has been designed, fabricated and measured. Results indicate that the proposed filter can suppress the sixteenth harmonic response referred to a suppression degree of 15 dB. Furthermore, the proposed filter exhibits a small size of 0.111 λg×0.091 λg, where λg is the guided wavelength at 1 GHz.

Patent
19 Jan 2012
TL;DR: In this paper, a low pass filter with an active low-pass filter and an amplification function was proposed to shorten the period of offset cancellation operation. But the proposed method requires two calibration resistors to be connected to the differential output terminals of an active filter having a filter process and amplification function.
Abstract: The present invention is provided to shorten the period of DC offset cancellation operation. One of terminals of two calibration resistors is connected to the differential output terminals of an active low pass filter having a filter process and an amplification function, and two input terminals of a voltage comparator and two terminals of a switch are connected to the other terminal of the two calibration resistors. In a calculation period of calculating digital control signals for reducing DC offset voltage, the voltage comparator detects calibration voltage depending on a voltage drop of one of the calibration resistors caused by analog current of a digital-to-analog converter. In a calibration period of reducing the DC offset voltage, the calibration analog current of the digital-to-analog converter responding to the digital control signal is passed to the input side of the filter via the switch.

Journal ArticleDOI
TL;DR: A 90 nm-CMOS power-optimized analog baseband chain for ultra-low-power impulse-radio ultra-wideband (IR-UWB) receivers is presented, which consists of the cascade of three biquadratic cells made up by opamps in a series-shunt configuration, which features high input impedance, low load effects in the cascade blocks, and better frequency response.
Abstract: A 90 nm-CMOS power-optimized analog baseband chain for ultra-low-power impulse-radio ultra-wideband (IR-UWB) receivers is presented. The proposed device merges the functions of a programmable gain amplifier (PGA) and a low-pass filter (LPF). It consists of the cascade of three biquadratic cells made up by opamps in a series-shunt configuration, which features high input impedance, low load effects in the cascade blocks, and better frequency response. The opamp parameters are included in the overall biquad transfer function. This allows getting very low power performance, since the opamp bandwidth is not required to be much larger than the filter cutoff frequency. Moreover, the current consumption is optimized according to the selected gain level (1.3 mA at 0 dB-gain up to 1.9 mA at 40 dB-gain). The PGA features a 0-40 dB programmable gain range with a 5 dB gain-step. The LPF performs a sixth-order 255 MHz low-pass frequency response. For the overall chain the IIP3 is 14 dBm at 0 dB gain, while the input referred noise is 12.5 nV/√Hz at 40 dB gain.

Journal ArticleDOI
TL;DR: In this paper, a three-pole filter capable to switch to three different states is designed using the MEMS contact type switches in tunable filters, which allows both the adjustment of resonant frequency and the input/output and inter-resonator coupling.
Abstract: By taking advantage of the MEMS contact type switches in tunable filters, a new method that allows both the adjustment of resonant frequency and the input/output and inter-resonator coupling is presented A three-pole filter capable to switch to three different states is designed using this method The measured center frequency for each state is 8, 9, and 10 GHz (25% tuning) with a constant bandwidth of around about 1 GHz The measured insertion loss of the filter is better than 35 dB for all three states

Patent
10 Dec 2012
TL;DR: In this paper, a pre-shaping adaptive filter has been proposed to increase noise cancellation performance in a high frequency band during the presence of focused or narrow-band noise energy in a low frequency band.
Abstract: An active noise control (ANC) processor has an adaptive filter that uses a reference signal to produce an anti-noise signal, and an error signal to evaluate cancellation performance. An adaptive filter algorithm engine configures the filter coefficients of the adaptive filter, in accordance with pre-shaped versions of the error and reference signals. The pre-shaping filter has a high-pass transfer function and enables the adaptive algorithm engine to increase noise cancellation performance in a high frequency band during the presence of focused or narrow-band noise energy in a low frequency band. Other embodiments are also described and claimed.

Journal ArticleDOI
TL;DR: In this article, a compact lowpass filter with sharp cutoff frequency response and wide rejection bandwidth is proposed, which has a simple structure and comprises one microstrip coupled-line hairpin unit, one spiral slot and two open stubs.
Abstract: A compact lowpass filter (LPF) with sharp cutoff frequency response and wide rejection bandwidth is proposed. The proposed LPF has a simple structure and comprises one microstrip coupled-line hairpin unit, one spiral slot and two open stubs. A demonstration filter with 3 dB cutoff frequency at 2.0 GHz has been designed and fabricated. Theoretical and simulated results are presented, which are in good agreement with the measured results.

Journal ArticleDOI
TL;DR: In this article, a CFOA-based lossy/lossless floating inductance circuit is introduced, which employs only two CFOAs along with only five passive components.
Abstract: A new CFOA-based lossy/loss-less floating inductance circuit is introduced which, in contrast to previously known configuration requiring three to four CFOAs, employs only two CFOAs along with only five passive components. The workability of the new FI circuit has been demonstrated by using it to design a second order notch filter and a fourth order Butterworth low pass filter by realizing the circuit using commercially available AD844-type CFOAs.

Journal ArticleDOI
TL;DR: In this paper, an integration algorithm for stator flux estimation of direct torque control (DTC) was presented, which only contains a fifth-order low-pass filter (LPF), a high-pass (HP) filter, and a simple logical calculation part, where the LPF and HP filter can effectively filter out HF harmonics and the dc drift in the back EMF, respectively.
Abstract: This paper presents an integration algorithm for stator flux estimation of direct torque control (DTC). This algorithm only contains a fifth-order low-pass filter (LPF), a high-pass (HP) filter, and a simple logical calculation part, where the fifth-order LPF and the HP filter can effectively filter out HF harmonics and the dc drift in the back EMF, respectively. The α- and β-axis back EMFs passing through the two filters will obtain β-axis stator flux linkage and opposite polarity α-axis stator flux linkage, respectively, and then by the logical calculation part can finally achieve α- and β-axis stator flux linkages. At any synchronous angular frequency, the amplitude- and phase-frequency characteristics of this algorithm are same as those of the pure integrator, and meanwhile its dc gain is zero. The proposed algorithm with high estimation accuracy behaves well in both steady state and dynamic performance when used in a DTC-based electrical excitation flux-switching generator dc power system, which is verified by experimental results.

Journal ArticleDOI
TL;DR: Numerical results show how the spectral lines and correlator model can affect the tracking performances, and the sensitivity of GNSS signals against the CW interferer is investigated by varying data bit duration or integration time.
Abstract: Analytical expressions are suggested for GNSS receiver performance such as the effective C/N0, code tracking (DLL) error and carrier phase tracking (PLL) error for a receiver affected by CW interference signals. The navigation signal model is applied to GNSS power spectral density (PSD) to interpret spectral line effects within receiver tracking low pass filter, limited by navigation data bits. A scaled envelope model is also introduced to estimate average susceptibility of signal against CW interferences. Numerical results show how the spectral lines and correlator model can affect the tracking performances, and the sensitivity of GNSS signals against the CW interferer is investigated by varying data bit duration or integration time.

01 Jan 2012
TL;DR: In this article, the authors presented the design techniques of low pass FIR filters using Blackman window method, Optimal Parks McClellan method and Genetic Algorithm method and compared them with other techniques.
Abstract: Digital filter are widely used in the world of communication and computation. On the other hand to design a digital finite impulse response (FIR) filter that satisfying all the required conditions is a challenging one. In this paper, design techniques of low pass FIR filters using Blackman window method, Optimal Parks McClellan method and Genetic Algorithm method are presented. The stability, number of components required and filter coefficients are demonstrated for different design techniques. It is shown that filter design by using GA is best because the numbers of components required are less and stability is more as compare with other techniques. Design comparisons are presented to show the effectiveness of GA optimization method