%0 Journal Article
%T Comparative Study of Resistorless Filters Using Differential Voltage Current Controlled Current Feedback Operational Amplifiers and Differential Voltage Current Controlled Current Conveyors
%A Costas Laoudias
%A Costas Psychalinos
%J ISRN Electronics
%D 2013
%R 10.1155/2013/910170
%X Differential Voltage Current Controlled Current Feedback Operational Amplifier is an attractive active element for realizing resistorless filters with a minimum active component count. This is verified through a design example, where a 3rd-order leapfrog filter has been realized using the AMS 0.35£¿¦Ìm CMOS process design kit. The performance of the Differential Voltage Current Controlled Current Feedback Operational Amplifier filter is evaluated and compared with that obtained by the corresponding filter, where Differential Voltage Current Controlled Current Conveyors have been employed. 1. Introduction The Current Feedback Operational Amplifier (CFOA) is a four terminal active element which offers particularly higher speed, higher slew rate, and better bandwidth than those achieved by the conventional voltage-mode op amps [1, 2]. A number of CFOA topologies with terminals of single type have been already introduced in the literature [3¨C6]. Enhanced CFOA topologies, including Fully Differential CFOAs (FDCFOAs) [7¨C10], Differential Voltage CFOAs (DVCFOAs) [11, 12], have been also published. Comparative studies of CFOAs and DVCFOAs have been performed in [4, 13], respectively. The realization of time-constants in filters, where the aforementioned types of CFOAs are utilized, is achieved by employing passive resistors. This is a drawback with respect to the nowadays analog filter realization trend, where resistorless filter structures with electronic tuning capability are preferred. As a solution, active resistors could be employed, but the performance of the resulted filter configurations in terms of linearity is worsened in this case. Resistorless topologies using CFOAs could be realized by employing the current controlled CFOA (CCCFOA) in [14]. The core of this active cell is constructed from translinear loops formed by a bipolar transistor. In addition, the minimum supply voltage requirement is equal to , where and are the base-emitter voltage of a bipolar transistor and saturation voltage of an MOS transistor, respectively. In order the CFOA filters to be compatible with the nowadays trend, a novel enhanced version of CFOA, mentioned as Differential Voltage Current Controlled Current Feedback Operational Amplifier (DVCCCFOA), will be employed for the realization of active filters. This cell has also the benefit for operating in a low-voltage power supply environment. As it will be proved through comparison results, the employment of the DVCCCFOA offers a reduced number of active component counts in comparison with the corresponding realizations, where
%U http://www.hindawi.com/journals/isrn.electronics/2013/910170/