The Research Of Minimum Mismatch Of Passive Network Into The Attenuator Network

With the rapid development of electronic circuit technology, in circuit design. Load match is still a very important issue. For example, the two-port filter network applied to the actual circuit. As the external environment is unstable that will cause the terminal load resistance changes, therefore, transmission characteristics of the filter will be affected by change of the terminals load. in the design of filters and matching networks, we would demand that the terminal load changes as large as possible will satisfy network filtering and the need of match:the minimum mismatch network.The paper is based of the minimum mismatch network,we research the effect of the characteristics of time-varying load with the high-pass,band-pass filter and the lossy pi-attenuator network. This thesis describes the development of the filter and filter classification, and systematic exposition the form of the four filters approximating function, analysis basic theory of the filter two-port network, introduce the minimum mismatch network of basic concepts, research methods and optimization goals. We focuses on the basic filter design method:frequency transform In the ADS we use frequency transformation method tdesign and simulation the 5-order minimum mismatch Butterworth, Chebyshev, Elliptic high-pass and band-pass filter network.By simulation the S parameters,the effect of time-varying load on the transmission characteristics of filter was observed. Analysis the effect of time-varying load on the passband reflection coefficient modulus and amplitude-frequency characteristics of three types filters. The characteristics of designed filter is better than prototype filter. The results demonstrate the optimized approach of minimum mismatch network is feasible.The design of minimum mismatch high-pass and band-pass filter meet the requirements to some extent, however, due to the simulation results can not break through the lower limit of 0.33. In order to break the boundaries. Finally, the paper quoted the minimum mismatch of pi-type attenuator network. Introduced the basic concepts and formulas. The design of Butterworth high-pass and band-pass filter as an example and be cascaded with the pi-type attenuator, the S parameters were simulated by using ADS software. Analysis the effect of the load change as large as possible on transmission Characteristics of the cascading network. Verify the pi-type attenuate or were optimized for the entire system performance, finally get the reasonable minimum mismatch network.