A Compact Switchable and Tunable Bandpass Filter

Abstract

In this paper, an integrated switchable and tunable bandpass filter is designed, simulated, and fabricated. This integrated bandpass filter is able to switch as well as tune in the ultra-wideband (UWB) as well as 2.4 GHz band. At first, a UWB bandpass filter is developed which consists of two bent shorted quarter-wavelength stubs and a connecting half-wavelength stub. Subsequently, a 2.4 GHz bandpass filter is realized by connecting another half-wavelength stub on top of the UWB filter. RF pin-diodes are used for switching the bands between UWB and 2.4 GHz bandpass filter. The switchable bandpass filter converts into a tunable filter by changing the inductance or the length of shorted stubs through the pin diodes. A detailed parametric analysis is done for calculating different stubs lengths of the UWB as well 2.4 GHz bandpass filter. The simulation results show a high rejection level of > 40 dB at the lower frequency and a low insertion loss of 0.8 dB in the passband for UWB filter. For 2.4 GHz bandpass filter, the simulation results show an insertion loss of 0.42 dB and a 3 dB bandwidth of 796 MHz. The filter is fabricated on a Rogers 4003 substrate, and the measurement results of the switchable filter in the UWB band show an insertion loss of 2.1 dB and a 3 dB bandwidth of 7 GHz. In the case of 2.4 GHz bandpass filter, the insertion loss is 0.78 dB.

A Novel Filter with Reconfigurable Bandwidth or Transmission Zeros Based on a Multiple-mode Stub-loaded Resonator

“…Compared with some other reported works, the proposed reconfigurable filter has more operating states by using fewer PIN diodes than [8][9][10][11][12][13][14], shown in Table 3.…”

“…Reconfigurable bandwidth filters are particularly useful in the design of highfrequency multifunction receivers that simultaneously support multiple information signals with different frequency bands and power level characteristics [1,2]. Various high-performance bandwidth reconfigurable filters have been designed by using varactor diodes [3][4][5] and PIN diodes [6][7][8][9][10][11][12][13][14] as tunable components. In [6], a bandwidth reconfigurable filter was implemented by using Semi-conductor Distributed Doped Areas (ScDDAs) as an integrated element to convert the resonator from a λ/2 open stub to a λ/4 stub.…”

“…In [9,10], reconfigurable bandwidth filters were designed based on a stub-loaded ring resonator. In [11], a PIN diode was used to control the connection state of two bent λ/4 resonators and one λ/2 resonator, which can be switched between wide band and narrow band. In [12], bandwidth reconfiguration was achieved by loading PIN diodes to change the length of the coupling stub.…”

Miniaturized bandwidth reconfigurable microwave bandpass filter

“…In line with this, the triple-band bandpass filter with two independently switchable passbands is described in Bandyopadhyay et al (2020). Some of the other important research on the development of reconfigurable bandpass filters are described in Huang et al (2014); Liu et al (2012) and Karim and Siyal (2019). In all the reported research works, the filters are designed to offer tuning over a narrow range of frequencies.…”