A Reconfigurable Current-Mode Antialiasing Filter for Low-Frequency Industrial Applications

This paper presents a current-mode antialiasing filter (AAF) based on second-generation current-controlled current conveyors (CCCII). It is specifically aimed at kHz-range industrial applications. The filter comprises two CCCIIs and two triple-MIM (Metal-Insulator-Metal) grounded capacitors. An OpAmp-based voltage-controlled current source handles the bias current control. The cutoff frequency of the proposed second-order AAF can be continuously tuned by exploiting the inversely proportional relationship between the parasitic impedance at the input X-terminal of the CCCII and its DC bias current, without relying on any additional circuitry. The performance of the proposed design has been validated through post-layout and corner SPECTRE simulations using a 0.18 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu \mathrm{m}$</tex> HV CMOS SOI process. The <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-3\ \mathrm{d}\mathrm{P}$</tex> cutoff frequency can be continuously tuned between 3.9 kHz and 34.9 kHz. A passband gain error of 1.127 % is reported, along with a Total Harmonic Distortion (THD) of 3.96 % for a 20 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu \mathrm{A}$</tex> peak-to-peak, 5 kHz sine wave input. The solution requires 0.67 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$mm^{2}$</tex> core area when leveraging triple-Mimcapacitors offered in the process. The proposed architecture achieves a control accuracy of 0.32 % with respect to the associated theoretical model, and 0.951 decades of tuning range. It consumes 3.52 mW under a supply voltage of 5 V.