Cross-coupled Combline Bandpass Filter using Active Capacitance Circuit

Abstract

In this paper, a cross-coupled combline bandpas passband response [6]. Therefore, we designed a 4 stage filter with active capacitance circuit using BJT is presented. The combline bandpass filter and used the negative resistances to proposed active combline banpass filter is composed of 2 normal the second and third resonators to obtain the optimal passband microstrip resonators and 2 microstrip resonators with active capacitance circuits. The negative resistance of the active response. capacitance circuit compensates the loss of the microstrip Also, we introduced a new structure of cross-coupled resonator. According to the Q distribution method, we arranged combline bandpass filter [7]. The new cross-coupled combline the 2 active resonators with high Q in the middle stages of the bandpass filter has good selectivity with two transmission filter. The proposed active bandpass filter has very good insertion zeros on the both sides of the passband. loss and selectivity with 2 transmission zeros. Moreover, it has good noise figure with common-emitter configuration. Therefore, In thls paper, we propose a design procedure of the crossit can be applicable to the modern wireless communication coupled combline bandpass filter and the negative resistance systems. The measured performance of the proposed filter has circuit, and present an experimental filter to verify this method. center frequency of 1.77 GHz, 5.1 % fractional band width, andThe proposed filter has center frequency at 1.77 GHz and maximum 2 dB insertion loss. The measurement shows good 5.1 % fractional band width (FBW).agreement with the simulated results.