Comment on "realization of series and parallel R-L and C-D impedances using single differential voltage current conveyor"

The comment is related to the recently published paper given in [ 1] dealing with the implementation of series and parallel R-L and C-D impedances using a single differential voltage current conveyor (DVCC). Nevertheless, straightforward analysis of the circuit in Fig. 3(b) of [ 1] and also given in Fig. 1 shows that it has a problem because it makes its input voltage V-in = 0. Therefore, it can not realize parallel (-L) -(-R) simulator as claimed in [ 1]. Alternatively, a circuit given in Fig. 2 for realizing parallel (- L) -(- R) simulator employing a single minus-type DVCC (DVCC-) and a minimum number of passive components is proposed. The introduced circuit employs a grounded capacitor, and requires no critical component matching constraints thus it is suitable for fully integrated circuit technology. If plus-type DVCC (DVCC+) is replaced instead of the DVCC-, this proposed simulator can realize parallel ( L) -( R) simulator.