Coplanar MMIC active bandpass filters using negative resistance circuits

Abstract

A second order active bandpass filter for a fmed centre frequency and a tunable one have been developed in coplanar line technique using negative resistance circuits. These filters operate in the 1.8 GHz band and have a 3 dB bandwidth of 110 MHZ. The tuning range of the centre frequency is 200 MHz. Each filter is fabricated on a GaAs substrate and occupies an area of 1.5 x 1.6 mm2 on the wafer including all biasing elements.

Narrowband MMIC Filters using Active GaAs Inductors. Application to HDTV

“…It can be seen that the filter made with the active inductor has a sharper response than the passive filter, which have a 3dB-bandwidth of 6.4 GHz. We obtain a better noise figure (1.95 dB) than for the passive filter and than other former active filter realized with the same bandwidth [7,8] as shown in figure 8.…”

Microwave Planar Varactor Tuned Bandpass Filters: Historical Overview

“…C. The active tunable filter using MMIC [42][43][44][45][46][47][48] The active MMIC tunable filters employ active resonators in which the loss is compensated using negative resistance as discussed in B [42][43][44][45][46][47][48]. For miniaturized designs lumped elements together with active devices to generate the negative resistances are combined to realize the resonators [42][43][44][45][46]. The quality factor of a resonator using MMIC passive components is quite low due to its small volume.…”

“…The quality factor of a resonator using MMIC passive components is quite low due to its small volume. In order to improve the quality factor, an effective method was also proposed [46]. The methods for the noise optimization and automatic frequency tuning are proposed by Kaunisto [42] in Fig.…”

“…In this paper, an attempt has been made to describe the advances in passive and active tunable filters. In section II and III, we will discuss the design schemes as well as the performances of the passive and active varactor tunable filters [35][36][37][38][39][40][41][42][43][44][45][46][47][48] realized in various configurations.…”

Ultra-compact MMIC active bandpass filter with wide tuning range

“…Furthermore, coupled-resonator filters can eliminate impractically-different component values between shunt and series branches in Butterworth or Chebyshev filters and offer the most freedom in the selection of component values [1]. Previous researches [2][3][4][5][6] have validated this concept as a viable approach for tunable active filters using GaAs technologies.…”