Khondker M.F. Rabbi

Highly Selective Reconfigurable Filter for UWB Systems

A novel highly selective compact reconfigurable filter with a switchable notched band for ultrawideband (UWB) systems is presented. The proposed filter exhibits two distinct features by altering switching device such as PIN diode (BAP65-02) in this case. First, a switchable notched band is generated which facilitates a rejection at 3.5 GHz to avoid interferences from the WiMAX systems. Later, a reconfigurable filter is developed which changes from bandpass to bandstop at the same UWB (3.1-5.2 GHz) spectrum. The filter shows very low pass-band insertion loss and five transmission zeros are created between passband edges to enhance the signal selectivity and broad rejection at the stopband. A filter sample is fabricated to provide an experimental verification on the proposed filter. The proposed filter is able to achieve significant size reduction as compared to an conventional reconfigurable filters and bandpass filters with notched band.

Optically reconfigurable microstrip UWB bandpass filters

This paper presents an optically reconfigurable microstrip ultra-wideband filter. A single optical switch comprised of a silicon wafer is activated using near infra-red light to select between either a bandpass or bandstop response. With the switch in the ON state, the circuit behaves as a bandpass filter while in the OFF state, the circuit behaves as a bandstop filter in the same frequency band. The proposed filter was designed, fabricated and tested. Its performance was evaluated through simulation and measurements.

Simulation of reconfigurable WLAN notch for UWB filters

This paper presents a third order ultra-wideband filter (3.1 GHz – 10.6 GHz) with a reconfigurable WLAN notch at 5.8 GHz. Filter reconfiguration in practice may be achieved by a switching element such as RF MEMs, a PIN diode or an optical switch. The switching element was modeled in simulation as a variable conductance line. The filter response shows a sharp rejection of the WLAN band and very low pass-band insertion loss. The quasi-elliptic nature of the bandpass response also contributes towards excellent lower and upper skirt selectivity.

Miniaturized dual-mode microstrip bandpass filter with a reconfigurable notched band for UWB applications

A novel, compact, and highly selective dual-mode microstrip bandpass filter with a switchable notched band is presented. A notched band is developed by employing an open-circuited stub which can be switched by a pin diode to avoid WLAN interferences (5.8 GHz) within the spectrum. The proposed filter achieves a significant size reduction (8.5 mm × 7.1 mm) as compared to conventional dual-mode filters with notched band. Simulated and experimental results of the designed filter were presented.

Linearity evaluation of optically reconfigurable UWB microstrip bandpass filter

This paper presents the evaluation of nonlinear distortion in reconfigurable Ultra-wideband (UWB) filter. An optical switch is used to switch the filter from bandpass to band stop response at the same UWB spectrum. The switch, which comprises of a silicon dice activated using near infrared light is investigated and the filter is evaluated for potential nonlinearity due to the presence of the switch. The filter was tested for nonlinear distortions when the Optical Switch was ON using 5MHz QPSK signal.

Optically reconfigurable CPW filters for UWB applications

A miniature optically reconfigurable ultra-wideband CPW bandpass filter is proposed. With the optical switch in the ON state (200W), the circuit behaves as a bandpass filter while in the OFF state (0W), the circuit behaves as a bandstop filter within the same frequency band. The simulation results of the proposed bandpass/bandstop filter are presented.