| At present, it plays an important role in almost electronic field of the high performance low pass filter. In the military ,for example, it uses for watercraft systems. it also uses for tone coding & encoding,echo elimination,sound synthesis,sound recognizing systems and so on. Furthermore, along with the improving of precision and reliability, there require for more high performance low pass filter. the reason is that it is impossible to work out an complete perfect low pass filter. But we can design an very perfect low pass filter in using some advanced technique.In this paper, via analyzing the passband,stopband and rolloff-band of the filter, attempt to use the concept of discrete signal, we implement the integrate circuit of our 6 order high performance low pass filter with butterworth technique and switched capacitor technique. The basic frame of the circuit is the single voltage input and single voltage output. And the basic cells are the switched capacitor and the operation amplifier.In this paper, we use the UP-DOWN design method to design the high performance low pass filter. Firstly, searching for large information of the high performance low pass filter, and tying up the foundry to get primary foundry information. Secondly, analyzing butterworth technique and switched capacitor technique, and carrying out the project and designing the corresponding circuit combining with the practice foundry in motherland. Thirdly, based on the cadence station, we simulate the filter with SPECTRE simulator and with bsim3v3 49 level model provided by shanghua foundry.And we edit and verify the layout with Ledit editor. Finally, fabricating and packaging and testing the high performance low pass filter. Based on the results of testing ,we rejigger the layout and confirm the final design.By making great efforts together , the products of high performance low pass filter have the characteristic of the cut-off frequency precision of 0.3%,the range of cut-off frequency of 0.1 Hz～20kHz and so on. The performance reach the original design target, and the filter can replace the overseas kindred products. |
