Signal flow graph realization of nth-order current-mode allpass filters using CFTAs

In this paper, a general synthesis procedure of using the signal flow graph (SFG) technique to realize an nth-order allpass current transfer function with current follower transconductance amplifiers (CFTAs) and grounded capacitors has been presented. The proposed circuit, in general, contains at most n+1 CFTAs and n grounded capacitors, without needing external passive resistors. It has been also show that the design procedure given here is simple structure, convenient tenability, and suitable for integration. Furthermore, the circuit has low sensitivity. PSPICE simulation results which agree very well with the theoretical analysis are also included.