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.

Ultra-wideband bandpass filter with hybrid quasi-lumped elements and defected ground structure

Abstract: A compact planar microstrip ultra-wideband (UWB) bandpass filter (BPF) is presented in this paper. The proposed UWB filter is realised by cascading a high pass filter (HPF) and a low pass filter (LPF). The designed five-pole HPF consists of inter-digital capacitors and short-circuited stubs and has a sharp falling edge at the cutoff frequency. Additional slots are adopted to improve the return loss performance in the pass band. The LPF is realised mainly based on a non-uniform defected ground structure array in the ground. Combining these two structures, a new UWB bandpass filter is fabricated and measured. The measured results show that the proposed BPF has a wide bandwidth from 3.0–10.8 GHz, associated the 40 dB shape factor as low as 1.2. A group delay variation of less than 0.15 ns in the pass band from 3.0–10.8 GHz is obtained. It also achieves a wide stopband with 20 dB attenuation up to 20.0 GHz.

New Bandstop Filter Circuit Topology and Its Application to Design of a Bandstop-to-Bandpass Switchable Filter

Abstract: In this paper, we show a new bandstop filter circuit topology. Unlike conventional bandstop filter circuit topologies, the new circuit topology has inter-resonator coupling structures. The presence of these inter-resonator coupling structures enables convenient switching from a bandstop to a bandpass filter. Using the new bandstop filter topology, this paper demonstrates a design of a frequency-agile bandstop-to-bandpass switchable filter. The filter is composed of tunable substrate-integrated cavity resonators and can be switched to have either a bandstop or bandpass response. Switching is achieved by turning on and off switches placed within the filter structure. A prototype of the proposed design is fabricated and the concept is verified experimentally.

The use of multirate notch filters in embedded-servo disk drives

Abstract: This paper explores the merits of using a discrete time multirate notch filter,in series with an FIR filter, for controlling a flexible mechanical system whose resonance is beyond one-half the servo sample rate (in other words, an aliased resonance). Through numerical optimization of the closed loop transient response, the performance of this architecture is compared to that of a single-rate notch with an FIR filter, and that of an FIR filter alone. For the specific example chosen here, it is seen that the multirate notch gives results that are far superior to either of the alternatives.

Hybrid filter for an alternating current network

Abstract: The invention relates to a hybrid filter for an alternating current network (6). The hybrid filter has a passive filter and an active filter (2,4) that are electrically connected in series, whereby the active filter (4) has a voltage source (8). According to the invention, a filter (14) adjusted to the nominal frequency of the alternating current network (6) is mounted electrically parallel to the active filter (4). This results in a hybrid filter for an alternating current network (6), whereby the active filter (4) is not subjected to fundamental frequency current component strain.