The Research And Design Of Current Mode Filters Based On CCCⅡ

As active components of filter circuits, Operational amplifiers have been familiar to us, but the filters composed by current conveyors are relatively strange. Compared with corresponding operational amplifier, regardless of size signal, current conveyor circuits can offer a higher voltage gain under larger bandwidth, that's to say, larger gain bandwidth product. Because of its unique current transmission characteristic, current conveyor circuits have been the basic block among the current-mode VLSI circuit. The current conveyor consisted of active components circuit system has played a very good role in simplifying structure, reducing power consumption and developing frequency domain etc. The circuits embracing filters, amplifiers and oscillators based on current conveyors have been put in a very important position in mobile communication and measure field.In recently ten years, design method of current mode circuit has got more and more attention and development, which has promoted analog integrated circuit into a new stage. Current mode circuit has become the branch of the new analogue integrated circuit with rapid speed, wide frequency, good linear and low voltage, and has a wide development.This paper studies the design and application of integrate circuit based on the second generation Current Controlled Conveyor (CCCII). Firstly it gives an overview of the importance and necessity of the research of analogy integrated circuit in present state. Then, the development of CCCII, the model of bipolar junction transistor (BJT) and CMOS transistor, the basic circuit units such as current modes are briefly introduced. With the topology and circuit, diagram of typical theory, the principle and feature of the CCCII are analyzed. The applications of the CCCII in the fields of the active network and signal process are synthesized. In addition, realization of analogue divider and oscillator using CCCII is introduced. With internationally latest studies, the paper also proposes the design of the two current-mode filters: one is second-order all pass filter based on CCCII, which can realize eight different transfer functions by selecting reactance without change its topology. The other is a current filter based on CCCII with three inputs and three outputs, which are capable to perform the functions of second-order low pass, high pass, band pass, band stop, all pass filtering without changing topology of circuits. The natural frequency and the quality factor of the filter can be tuned independently. Both of the filters are electronic tunable and integrated conveniently and compatible with VLSI technology. PSPICE simulation results of proposed filter circuits are almost identical with the theoretical analysis. Finally there is a conclusion and prospect for this paper.