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.

Analysis and Design of Two-Port $N$ - Path Bandpass Filters With Embedded Phase Shifting

Abstract: N-path switched- RC circuits are a promising solution for realizing tunable high- Q filters on chip. Here, a novel method of embedding phase-shifting functionality into the two-port N- path filter response by shifting the phase of the input and output clock sets relative to each other is introduced. Furthermore, a two-port design allows us to embed variable attenuation that can be useful in applications such as wideband self-interference cancellers and phased-array front ends, where filtering, phase shifting, and variable gain are functionally required. The effect of the embedded phase shift is analyzed with linear periodically time-variant theory and has been verified through simulations and measurement. Measurement results are presented for a two-port N- path filter implemented in a 65-nm CMOS 0.8-1.4-GHz highly reconfigurable self-interference canceling receiver. The two-port filter achieves 13-dB gain control and full 360° phase-shift range for the in-band transfer function.

Multilayer Planar Tunable Filter With Very Wide Tuning Bandwidth

Abstract: In this paper, we propose and develop a partially shielded tunable filter structure using a varactor-loaded split-ring resonator. The novel physical topology of the filter is suitable for vertical stacking of filters and enables a compact multilayer tunable filter for applications requiring a very wide tuning range. The capacitance range and ratio needed to achieve the designated tuning range are presented, and analytical solutions are given for the second and third higher order modes for synthesis in the spurious-free filter operation range. Two prototypes are developed. A partially shielded tunable filter using varactor-loaded split-ring resonators is developed to verify the design method and to demonstrate the wide tuning range of a tunable filter. To further extend the tuning range, a filter bank with three stacked tunable filters at different frequency bands are designed and developed. With slight overlap between neighboring bands, a continuous tuning range of more than 6:1 is achieved.

Universal Current-Mode Active-C Filter Employing Minimum Number of Passive Elements

Abstract: A universal current-mode active-C filter simultaneously realizing low-pass, band-pass and high-pass responses is proposed The filter can also realize notch and all-pass responses with interconnection of relevant output currents The presented filter employs four second-generation current controlled conveyors (CCCIIs) as active elements and only two capacitors as passive elements The proposed active-C filter can be tuned electronically, and has low element sensitivities

Loss sensitivities in singly and doubly terminated filters

Abstract: The loss of a conventional doubly terminated filter is far less sensitive than the loss of a singly terminated filter to errors in the component values. This property, first pointed out in 1966, has motivated many new high quality RC-active and digital filter design techniques. It is not so widely appreciated, however, that this superiority of the doubly terminated filter also holds for errors in the terminating resistances as well as for errors in the components inside the filter. The nature of these sensitivities in both types of filter is discussed in some detail, and Illustrated by means of a numerical example.

Voltage offset loop for a switching controller

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.