The Research On FTFN's Application In Analog Integrated Circuit

Filter circuit of active components has been used widely, but it has a few obvious shortcomings, such as that it is restricted by the parameters of operational amplifier, that it can not work in high frequency range. In a lot of active devices, four-terminal floating nullor(FTFN), a new circuit model , has received considerable attention, as it is a more flexible and versatile building block than an operational amplifier and a current conveyor. This is due to the fact that the FTFN can replace nullator/norator pairs without any conditions and it has good high frequency characteristic.This paper firstly set forth the importance of the research of analog integrated circuit and it introduces the circuit principle of FTFN, FTFN with multiple output, FTFN with variable current gain, CMOS fully balanced FTFN and their application in the analog integrated circuit. Based on analyzing FTFN's application in the design of the first-order filters and the second-order filters, two configurations for realizing current-mode second- order multifunctional filter using FTFN with multiple output are presented in this paper, which are capable to perform the functions of low pass,high pass,band pass,band stop,all pass filtering,adjusting the natural angular frequencyω0 and the quality factor Q independently,PSPICE simulation results of proposed filter circuits are given to confirm the theoretical analysis.In modern systems,analog and digital circuits are implemented in the same inregrated circuit chip.Therefore,A configuration for realizing voltage-mode second-order multifunctional filter using fully balanced CMOS FTFNs are proposed.which owns many advantages,such as realizing multiple functions simultaneously,lower power consumption,be suitable for mixed analog and digital circuits and realizing the allpass function under the condition that no matching condition exists.At the same time,PSPICE simulation results verify their performance.In addition, the application of FTFN in the design of active networks, the realization of immittance function and the design of oscillators are analyzed.The realization of current-mode transfer function and inverse transfer function using FTFNs ,and the realization of floating M,L,R or series E,D,C immittance using FTFNs,and the design of sinusoidal oscillators using FTFNs are mainlyanalyzed.PSPICE simulation results of the relative circuits are given to confirm the therotical analysis.