Cai Li,Ma Xikui
(School of Electical Engineering,Xi'an Jiaotong University, Xi'an 710049, China)
Abstract:The formulations of the centre frequency, quality factor related to the magnitude and phase of the integrator error function are respectively derived for the log domain bandpass filter, based on the analysis method of the integrator error function. The relationships between the centre frequency, quality factor and the transistor nonideal parameters ( R E, R B, finite ¦Â and Early voltage V A) are obtained. It is shown that the centre frequency is mostly affected by parasitic resistances R E and R B, the centre frequency and quality factor are affected by the finite ¦Â, and the effects of the finite V A on the filter are small. The electronic compensation schemes are given, which can evidently improve the performance of the nonideal bandpass filter. SPICE simulations are performed to verify the theoretical results. The results obtained provide a theoretical basis for the exact designs and applications of the log domain filters.
Keywords:log domain filter;integrator;nonideality;error function