A filtering impedance transformer with high transforming ratio

Abstract

A filtering impedance transformer with high transforming ratio and good suppression out of band is presented in this article. Design parameters of the proposed configuration are analyzed. For verification, a 50 to 500 Ω transformer operating at 3 GHz has been designed, fabricated, and measured. The measured maximum insertion is about 0.87 dB and the measured return loss is better than 18 dB from 2.71 to 3.29 GHz, which are in good agreements with the simulated ones.

A Dual-Band Dual-Output Filtering Power Amplifier Based on High-Selectivity Filtering Impedance Transformer

“…According to the parameters of r = 4 given in [3], the spacing gap in the physical size of the CL may be too small and difficult to fabricate, thus limiting its application. The FIT in [4] demonstrates the simulation results of FBWs around 19%; however, it is difficult for the circuit structure to obtain a set of parameters that are convenient for layout in the case of r = 4 and FBWs less than 10%, such as the scenario of this work. Next, two FITs with extremely low and high termination impedance are proposed in [7].…”

“…Also, two CLs and one stub are utilized to realize the impedance transformation with International Journal of RF and Microwave Computer-Aided Engineering low termination impedance in [9]. Then, in [3,4], two FITs with high termination impedance are proposed. According to the parameters of r = 4 given in [3], the spacing gap in the physical size of the CL may be too small and difficult to fabricate, thus limiting its application.…”

“…Impedance transformer (IT), as one of the basic components of radio frequency (RF)/microwave systems, can be utilized to achieve the desired impedance matching and the efficient power transmission. To improve the frequency selectivity, various ITs with bandpass response have been widely investigated [1][2][3][4][5][6][7][8][9][10][11] and applied to matching network designs of power amplifiers (PAs) [8][9][10][11]. In [1][2][3][4][5], different coupled-line structure filtering impedance transformers (FITs) with ultrahigh transforming ratio realize low/high termination impedance transformations, respectively.…”

“…To improve the frequency selectivity, various ITs with bandpass response have been widely investigated [1][2][3][4][5][6][7][8][9][10][11] and applied to matching network designs of power amplifiers (PAs) [8][9][10][11]. In [1][2][3][4][5], different coupled-line structure filtering impedance transformers (FITs) with ultrahigh transforming ratio realize low/high termination impedance transformations, respectively. Also, cross-shaped [6] and coupled-line structure [7] ITs are presented, both of which can implement an extremely low/high impedance transformation.…”