Simple Current-Mode Squaring and Square-Rooting Circuits: Applications of MO-CCCCTA

This work provides new designs of simple current-mode squaring and square-rooting circuits using multiple-output current controlled current conveyor transconductance amplifier (MO-CCCCTA) as an active building block. Since the proposed circuits need no other external components, they are capable of high-frequency operation and well fitted for IC fabrication. Furthermore, they are insensitive to ambient temperature and their gains can be controlled easily by adjusting the bias currents of MO-CCCCTA. Additionally, the effects of MO-CCCCTA non-idealities on the designed circuits have also been investigated and discussed. Simulation results generated through PSPICE software using TSMC 0.18 µm CMOS process parameters have been presented to justify the theoretical analysis. The static power consumption, bandwidth, and maximum linearity error in dc transfer characteristic measurement for the square-rooting circuit are found to be 0.17 mW, 445.63 MHz and 1.12 %, while for the squaring circuit they are 0.326 mW, 61.15 MHz and 2.38 %, respectively. The application of the reported circuits as a 2-input vector summation circuit has also been included to strengthen the design ideas. HIGHLIGHTS Simple structures of fully integrable current-mode squarers and square-rooters with low component count and lower power dissipation The circuits are insensitive to temperature drift and their gains can be controlled easily by adjusting the bias currents of MO-CCCCTA Bandwidth, static power dissipation, linearity error of square-rooter are 445.63 MHz, 0.17 mW & ≤ 1.12 %; and for the squarer 61.15 MHz, 0.326 mW & 2.38 %, respectively GRAPHICAL ABSTRACT

The influence of the baseline drift on the resulting extinction values of a cavity attenuated phase shift-based extinction monitor (CAPS PMex)

The effect of the baseline drift on the resulting extinction values of three cavity attenuated phase shift-based extinction monitors (CAPS PMex) with different wavelengths and the respective correlation with NO2 was analysed for an urban background station. A drift of more than 0.8 Mm-1min-1 was observed for ambient air, with high probability caused by traffic-emissions-driven changes in carrier gas composition. The baseline drift leads to characteristic measurement artefacts for particle extinction. Artificial particle extinction values of approximately 4 Mm−1 were observed using a baseline period of 5 min. These values can be even higher for longer baseline periods. Two methods are shown to minimize this effect. Modified continuous baseline values are calculated in a post-processing step using simple linear interpolation and cubic smoothing splines. Both methods are useful to reduce artefacts, although the use of cubic smoothing splines gives slightly better results. The extinction artefacts are diminished and the effective scattering of the resulting extinction values is reduced by about 50 %.