High-Performance Low-Pass Filter Using Stepped Impedance Resonator and Defected Ground Structure

Abstract

A microstrip low-pass filter (LPF) using reformative stepped impedance resonator (SIR) and defected ground structure (DGS) is proposed in this paper. The proposed filter not only possesses the advantage of high frequency selectivity of SIR hairpin LPF with internal coupling, but also possesses the large stop-band (SB) bandwidth by adjusting the number and area of DGS units. The LPF proposed in this paper possesses the properties of miniaturization, wide SB, high selectivity, and low pass-band ripple (PBR) simultaneously. The characteristic parameters of the proposed LPF is that: the pass-band (PB) is 0~2 GHz, the PBR is 0.5 dB, the SB range is from 2.4 GHz to 9 GHz when the attenuation is under 20 dB, and the maximal attenuation could reach 45 dB in the SB. The size of this proposed LPF is 0.13 λ × 0.09 λ ; λ is the corresponding wavelength of the upper PB edge frequency of 2 GHz.

A 17 GHz inductorless low‐pass filter based on a quasi‐Sallen–Key approach

“…The FVF has been designed to achieve a value of the output resistance R out that ensures a relative error on the resonance frequency below 15%. By applying Equations ( 10) and (11) in the case of a purely capacitive load C L of 10fF and considering the values of the components in Table 1, we get a maximum allowable value of 25Ω for the output resistance. The evaluation of the desired value of R out has been repeated with the simulator taking into account the effective implementation of the output stage; Figure 6 shows the trend of f 0 and Q versus R out .…”

“…The traditional approach to design filters in that frequency range involves the use of inductors in passive networks or in active stages, [10][11][12] and high-order filters are typically designed according to the gyrator synthesis method starting from an LC-ladder prototype, 13,14 to the leapfrog LC-ladder simulation technique 15 or as a cascade of biquadratic sections (biquad). 16,17 The use of inductors is however not a good solution for highly integrated systems, since integrated spiral inductors require a huge amount of silicon area, and the constraints on practically realizable values could lead to very high power consumption for the active filter or for the buffer driving the passive one.…”

Polyester‐based wearable bandpass microstrip filter

“…In wearable systems and devices, microstrip filters are essential components to select desired frequency bands or reject unwanted frequency bands. Different types of microstrip filter have been proposed in the literature 7–16 . Bindu and Mohanan 7 reported an ultra‐wideband (UWB) filter using stepped‐impedance resonators (SIRs) to control lower cut‐off frequency and interdigital linked lines with control of upper cut‐off frequency.…”

“…It consists of two high‐impedance cells that are combined by a stub‐loaded transmission line. Zhang et al 12 elaborate use of a reformative stepped impedance resonator (SIR) and a defective ground structure (DGS)‐based microstrip low‐pass filter (LPF). Parameswaran and Raghavan 13 present a typical microstrip line‐based quasi‐elliptic low pass filter.…”

“…Different types of microstrip filter have been proposed in the literature. [7][8][9][10][11][12][13][14][15][16] Bindu and Mohanan 7 reported an ultra-wideband (UWB) filter using stepped-impedance resonators (SIRs) to control lower cutoff frequency and interdigital linked lines with control of upper cut-off frequency. Singh et al 8 present use of three interdigital edges coupled microstrip lines, SIR open stub, and a RO4003C substrate to create a planar UWB bandpass filter from 3.1 to 10.6 GHz.…”