Amarjit Kumar

Coupled stepped-impedance resonator based dual-band adaptable bandpass filter with tunable lower band central frequency and bandwidth

We report a microstrip coupled stepped-impedance resonators (CSIRs) based concurrent dual-band reconfigurable band-pass filter (BPF) with tunable lower band central frequency and bandwidth through a single DC bias control voltage. Semiconductor varactor diodes have been used as the tuning element for getting continuously tunable frequency and bandwidth response. Tuning has been introduced in lower band central frequency and lower frequency bandwidth by properly incorporating varactor diodes in the CSIR structure. Varactor diodes incorporated in series configuration with the resonator in the CSIR structure provides adaptability in lower frequency band while upper band is fixed. Design approach and analysis have been provided along with the measurement results for the validation of the proposed concept.

Reconfigurable Concurrent dual-band Low Noise Amplifier for noninvasive vital sign detection applications.

Concurrent dual-band reconfigurable low noise amplifier (LNA) for noninvasive detection of human vital signs has been reported in this paper. The reconfigurable output matching network used in this LNA (PHEMT ATF-36163) consists of two shunt stubs terminated by varactor diodes (SMV1232-079LF); while the matching network at input side of the LNA has been designed for fixed dual band operation. The measured characteristics of the fabricated prototype shows that the gain of the LNA varies from 3 dB to 12.2 dB in the frequency range of 2.3-2.5 GHz; while it varies from 9.5dB to 12.9 dB in the frequency range of 4.2-4.6 GHz for a variation in varactor voltages from 0-10V. The simulated value of the Noise Figure of the amplifier is ~ 0.5 dB and 2.5 dB at the centre frequency of the corresponding frequency bands.

A compact reconfigurable concurrent dual-band Wilkinson power divider for noninvasive vital sign detection applications

A Compact Concurrent dual-band Reconfigurable Wilkinson power divider (WPD) for noninvasive human vital signs detection is reported in this paper. The Tuning element is incorporated into the shunt element of the dual-band impedance transformer of the concurrent dual-band WPD circuit. Design approach along with design equations is provided to enhance further design utility. Tunability of both bands (2.45/5.25 GHz) is investigated using a single varactor diode thereby resulting compact size and less cost. The performance of the WPD as a function of various tuning voltages is studied in detail. A hardware prototype is realized to work at WLAN bands and exhibiting a total tunability bandwidth of 385 MHz and 735 MHz at lower and upper frequency bands, respectively, for a varactor voltages varying from 0-15 V. The calculated and measured results are in good agreement. The measurement analysis shows that the proposed compact reconfigurable dual-band WPD can be used as a subsystem in a noninvasive multi-band RF vital sign detection system for the better detection of human vital signs such as heartbeats and respiration rate.