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 varactor-tuned, active microwave band-pass filter

Abstract: A microwave tunable high-Q active bandpass filter was developed using a varactor diode for tuning and a MESFET to provide negative resistance for increasing the tank circuit Q-value. Tuning ranges of 500 MHz for the one-pole filter and 430 MHz for the two-pole filter were achieved with a center frequency of 10 GHz. A 3-dB bandwidth of 20 MHz for the one-pole filter and 80 MHz for the two-pole filter was obtained. The passband insertion loss is typically 0+or-1 dB. >

An integrated common mode and differential mode transmission line RF-EMI filter

Abstract: The increasing frequency and shrinking size of power electronic converters present growing RF-EMI challenges. As subsequent research on the integrated differential mode RF-EMI filter, this paper proposes an integrated differential mode (DM) and common mode (CM) RF-EMI filter. The filter has a transmission-line-like structure, incorporating CM and DM filter elements in the busbars. Utilizing the proximity effect, the filter guides the high frequency CM and DM currents into appropriate high damping filter elements and achieves high attenuation. An experimental unit has been constructed and small-signal tests have demonstrated its high damping factor for both CM and DM noise at high frequencies. A distributed model based on multi-conductor transmission structure theory is presented in this paper.

Tri-mode adaptive filter and method

Abstract: An adaptive filter having a hybrid structure and capable of operating in a tri-mode regime is disclosed. The tri-mode adaptive filter includes three sub-filters which operate in a fast convergence mode, a slow convergence mode, and a freezing mode respectively. The adaptive filter further comprises a quality detector which measures non-convergence and a near-end signal of the tri-mode filter and generates a feedback signal which is sent to a switching means. In response to the feedback signal, the switching means provides switching between the sub-filters so that one of the sub-filters operates at a time, providing adaptive filtering in accordance with its corresponding filtering method. In the embodiment of the invention the sub-filters operating in fast, slow and freezing mode are represented by Conjugate Gradient Fast Affine Projection (CGFAP) adaptive filter, Normalized Least Mean Square (NLMS) adaptive filter and Freezing adaptive filter respectively, wherein the Freezing filter operates with constant adaptive filter coefficients, i.e. without updating the filter coefficients, thereby providing convolution without adaptation. Corresponding method of adaptive filtering is also provided.

Active Filter Design Techniques

Abstract: Active filters are one of the most common and useful applications for op amps. Traditional methods of filter design presented in previous texts focused on detailed mathematical analysis based on transfer equations. A concise, to-the-point, quick design technique is proposed to cover the vast majority of filter needs with as few op amps as possible. Although a truly universal filter design board is elusive, a small set of boards are introduced that will implement all filter responses. Filter design utilities are introduced to calculate those responses.

Analog and digital filter design using C

Abstract: Introduction to filters and filter design software analogue filter approximation functions analogue lowpass, highpass, bandpass and bandstop filters analogue frequency response calculation and display analogue filter implementation using active filters introduction to discrete-time systems infinite impulse response (IIR) digital filter design finite impulse response (FIR) digital filter design digital filter implementation using C. Appendices: technical references code organization.