Voltage-controlled filter

About: Voltage-controlled filter is a research topic. Over the lifetime, 5514 publications have been published within this topic receiving 70872 citations. The topic is also known as: VCF.

A compact LTCC ultra-wideband bandpass filter using semi-lumped parallel-resonance circuits for spurious suppression

Abstract: A very compact ultra-wideband (UWB) bandpass filter with both high selectivity and suppressed spurious passband is implemented in the low-temperature co-fired ceramic (LTCC) substrate. By using the optimum distributed highpass filter structure of 11th-order, an ultra-wideband filter with the bandwidth from 3.1 GHz to 10.6 GHz is realized. In this study, the semi-lumped parallel resonance circuits are adopted in conjunction with the optimum distributed highpass filter, so that two finite transmission zeros may be created to suppress the spurious passband. The implemented filter exhibits a good frequency response to meet the Federal Communication Committee's (FCC's) limit and has a very compact size of 0.22 lambdag times 0.187 lambdag times 0.0246 lambdag (4.2 mm times 3.5 mm times 0.46 mm), where lambdag is the guided wavelength of the multilayer structure at 6.85 GHz.

FSF (frequency sampling filter) bank for adaptive system identification

Abstract: Some researchers have explored the use of filter banks to improve the performance of adaptive algorithms. However, some of these approaches have shown degradation in performance. A new class of filter bank (ideal orthogonal filter bank) is defined, which enables one to avoid the degradation, even if one chooses critical subsampling in adaptive filtering. A filter bank (pseudo OFB) whose frequency response is the same as that of the ideal OFB at discrete frequency points is proposed. As a result, using the proposed filter bank, one can identify an unknown system at the discrete frequency points. >

Lightweight electromagnetic interference filter

Abstract: A low pass filter includes a differential mode filter and a common mode filter. The common mode portion of the filter includes at least one inductor and one capacitor, as well as a damping circuit with at least one capacitor. The low pass filter has a reduced weight, which is useful in circumstances in which weight is a significant factor, such as in aircraft.

Programmable Bandpass Filter and Tone Generator Using Bucket-Brigade Delay Lines

Abstract: Bucket-brigade devices have been used to build a new type of active filter that is equivalent to a second-order digital filter without the need for complex analog-to-digital conversion. The filter response characteristics, i.e., center frequency and bandwidth, depend on the circuit parameters of gain and clock frequency, both of which may be electronically controlled. By using a variable clock signal, 1023 frequencies can be accurately selected by the proper setting of ten switches. The selected clock frequency uniquely determines the center frequency of the bucket-brigade filter. The programmable feature of the clock circuit, therefore, allows the convenient selection of the center frequency of the bandpass filter. A slight modification to the programmable bandpass filter converts it into a programmable oscillator. Thus, any one of 1023 tones can be generated by the proper setting of the switches. A device that exhibits both filter and oscillator functions has been demonstrated in the laboratory.

Receiver having an adaptive filter and method of optimising the filter

Abstract: A receiver comprises an adaptive filter having an input for a digitized input signal, means for storing a pre-designed filter characteristic, means for analyzing a digital. representation of the input signal to determine a desired position of the filter characteristic to match the system requirements, and means for adapting the stored pre-designed filter characteristic in the frequency domain and/or the time domain to match the system requirements and for transforming the adapted filter characteristic to the time domain to update coefficients for the adaptive filter and for loading updated coefficients into adaptive filter. The updating of the coefficients may be done periodically. The adaptation may be one or more of adjusting bandwidth, frequency shift and, in the case of a bandpass characteristic, superimposing characteristics.