Novel possibilities in square-root domain circuit design

Square root domain circuits are a subclass of the companding circuits propoundlarge dynamic range under low-voltage/low power, operating in high frequencies,and electronically tuneablity using DC current sources. Due to these advantages,companding circuits are compatible with CMOS VLSI technology. Since digitalcircuits are implemented in this technology, design of companding circuits hasreceived great attention.In this thesis, first order lowpass, second order lowpass, second order bandpassfilter and an oscillator designed in square root domain are presented. Losslessintegrator, first order highpass, allpass filters; second order highpass, notch withregular, highpass and lowpass cases, allpass filters; Kerwin-Huelsman-Newcombbiquad filter; Tow-Thomas biquad filter; fifth order Butterworth lowpass filter andquadrature oscillator are proposed as novel in the literature. All square root domaincircuits are designed by using state space synthesis method. The cut-off frequencyand the quality factor of filters are electronically tuneable by changing externalcurrents and dimensions of MOS transistors, respectively. At the same time,oscillation frequency and oscillation condition of oscillators are adjustable byexternal currents. Only MOS transistors and grounded capacitors are used withsingle power supply. The proposed filters have low THD values, low powerconsumption, large dynamic range due to having externally linear internallynonlinear structures.