Highly-Accurate Fractional-Order Microwave Differentiators for Band-Specific UWB Applications

Abstract

Highly accurate designs of band-specific fractional-order microwave differentiators are proposed to operate in lower and upper frequency bands of UWB range. Firstly, fractional-order digital differentiators are obtained by minimizing the magnitude error function of a single-zero multi-pole transfer function. Absolute relative error (ARE) analysis clearly demonstrates that the proposed lower and upper band fractional-order digital differentiator designs are having highly accurate magnitude response and outperform the existing fractional-order differentiators with maximum ARE values of − 44.14 dB and − 48.79 dB respectively. To operate in microwave range, these designs are realized using Z-domain chain scattering parameters of equal-electrical length line elements. Microstrip configurations obtained for lower and upper band fractional-order microwave differentiators consist of a short-circuited shunt stub and three serial transmission line sections. Implementation of designs is done on Rogers RO3003 substrate having thickness 0.75 mm. Measured results for transmission coefficient of lower and upper frequency band designs are found to be in good agreement with simulated ones over the frequency range 1.2 to 6.2 GHz and 6 to 10.9 GHz respectively.