| Continuous-time filter is of some prominent advantages, such as high processing speed, simple circuit configuration, and low power consumption. Which is because that, it needn't A/D switch, data processing, D/A switch technique and so on to finish filtering function with analog signal like digital filter, and it needn't switch action to sample data in the discrete time with analog signal like switched capacitor filter. So it has been widely used in the area of communication, electronic measurement, instruments, apparatus instruments, automation, etc. It is especially used in digital and analog mixed signal processing and communication integrated circuit.In recent years, the superiority of current-mode signal processing technique has been known by more and more people, and it has become the main developmental power of fully integrated continuous-time signal processing. Current-mode filter becomes the new research direction in the world, as its high speed, low power consumption and simple configuration. Current-mode continuous-time filter is one of the current-mode circuits, so it has characteristics of current-mode circuit. Typical current-mode continuous-time filters include current-mode filter based on current mirrors, current-mode filter based on OTA-C and current-mode filter based on current conveyor. They are rapidly developed in bandwidth, speed, precision, etc, so they bring the filter theories to noble times of fully integrated system development.The third generation current conveyor has some characters, such as low plus error, good linear character, wide frequency response and high output impedance. So the current-mode continuous-time filter based on CCIII becomes the new research direction in the world. In recent years, the study of current-modecontinuous-time filter based on current conveyor inside and outside of the country is basically the second generation current conveyor technique and the improved technique of CCII. So far, there are only few articles on CCIII and its improved circuit, the design of current-mode filter based on CCIII. Just as the reason, this paper studies the design of the third generation current conveyor and the fully integrated current-mode continuous-time filter. It is based on the design idea of some existing CCII circuits, falling to designing the third generation current conveyor filter, which makes the performance more predominant. To sum up, the main conclusion and production as follows:1. In the paper, the history, sorts, significance and evolution of fully integrated continuous-time filter are reviewed. The MOS model, filter basic theories, basic OTA circuit and basic circuit cells of current-mode filter based on OTA are investigated in detail; Conclude basic module cells of CMOS analog integrated circuit and their function. Firstly, it is analyzed DC model, AC model and PSPICE model of MOS, then conclude the type of basic module cell of CMOS analog integrated circuit and its function. Next, the type of filter is discussed, the general form of transmit function in N-step low-pass, high-pass and band-pass filter is given. All the contents settle the theoretic basic for the design of filter latter.2. In the paper, the structure character of the first, the second and the third generation current conveyor is compared. The purpose, implemented theory and basic implemented circuit of the third generation current conveyor are researched in detail.Firstly, compare the structure character of the first, the second and the third generation current conveyor; discuss the purpose, implemented theory of the third generation current conveyor; study the basic implemented circuit of the thirdgeneration current conveyor in detail; analyze the circuit character by computer simulation. Then, improve the basic implemented circuit of CCIII in two aspects. The one is to improve the circuit character by changing the parameter of MOS. This is especially obvious in improving voltage-following character, which improve theβof basic model from 0.9545 to 0.9802, and also improve theβof source-together model from 0.9645 to 0.9847. The other is to change the circuit structure of CCIII. This means improve the circuit character, and also increase the output resistance, which increases from grade K ? to grade M? .3. The design of current-mode continuous-time two-step filter based on CCIII. Model is studied in detail. The circuit designing and sensitivity analyzing of two-step low-pass, high-pass and band-pass filter based on CCIII is given, and the circuit precept is validated by computer simulation.Firstly, compute the design theory of current-mode continuous-time two-step filter based on CCIII in detail. The circuit designing and sensitivity analyzing of two-step low-pass, high-pass and band-pass filter based on several kinds of CCIII is given, and the circuit precept is validated by computer simulation. Then, give the current-mode continuous-time two-step band-pass filter based on CCIII-Level3 model, the current-mode continuous-time two-step low-pass filter based on CCIII source-together model, and the current-mode continuous-time two-step high-pass filter based on CCIII source-together model. Finally, compare current-mode continuous-time two-step filters based on different CCIII models. The simulation shows that, Although the transmission performance of CCIII-Level2 basic model is good, but because of it's low output resistance, it was unable to implement the current-mode continuous-time two-step filters, which meet the design requirements; the center frequency of the current-mode continuous-time two-step band-passfilter ,which based on CCIII-Level3 basic model,is most close to the design values; the cutoff frequency of the current-mode continuous-time two-step low-pass filter based on CCIII source-together model coule meet the basic design value; the current-mode continuous-time two-step high-pass filter based on CCIII source-together model has good performance in the frequency range of 1 MHz, The cut-off frequency can be more close to the designed value by adjusting external capacitance.This conclusion will be useful to the choice of CCIII model when filter is designed practically.In the information times, the development of integrated circuit is focused more attention to, and the research of fully integrated current-mode continuous-time filter's layout is just under way. It is more and more necessary to develop and perfect the theories and methods. Surrounding correlative task and developing trend, current-mode continuous-time filter will be developed and innovated continuously. It can be believed that the electronic production based on the third generation current conveyor will be more and more abundant, and their performance will be more and more predominant in future. They will product far-reaching effect in the area of communication and electronics, signal and information processing, neural network (NN), etc, and bring profound revolution in the area of microelectronics along with the deeper research.
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