A Study on the Gm Based Current Mode Capacitance Multipliers Implementation

This paper presents a detailed study of a current mode capacitance multiplier architecture that uses transconductance amplifiers. A frequency analysis carried on the structure built with ideal transconductors reveals an equivalent input impedance model given by a series of a capacitor and a resistor. A second analysis, considering non-ideal effects such as input and output capacitances or non-zero output conductance, shows that the initial model has to be completed with three other elements. It is demonstrated that the parallel input conductance determines the low frequency resistive behavior of the structure. The model resulting from this analysis is validated by simulations of two implementations using transconductance amplifiers that have similar transconductance characteristics but non-equal output conductance.