A Dual-Band Impedance Transforming Technique With Lumped Elements for Frequency-Dependent Complex Loads

Abstract

Abstract-In this paper, a new technique to realize lumped dual-band impedance transformers for arbitrary frequency-dependent complex loads is proposed. For the complex impedance transforming, closedform design equations are presented for a series-shunt and a shuntseries type and a concept of combination is also presented. They use the proposed equation of input impedance. This equation can easily and exactly obtain the input impedance of any two-port network using the ABCD matrix. Then in order to realize dualband operation, four topologies comprising two types and a design method are presented. This technique is numerically demonstrated by various examples with excellent results and it has advantages of simplicity, intuitiveness and versatility because it is a general solution for complex impedance transforming. The proposed dualband impedance transforming technique can be utilized for practical matching problems such as microwave amplifiers and other devices.

A Coupled-Line Based L-Section Dc-Isolated Dual-Band Real to Real Impedance Transformer and Its Application to a Dual-Band T-Junction Power Divider

“…Furthermore, there could be a situation when the load impedance is complex as well as frequency-dependent, for instance, the input impedance of transistor while looking into its gate terminal. The design techniques reported in [12][13][14][15][16][17][18][19][20][21][22] pretty much address this scenario but with some limitations. For example, the technique reported in [12] provides matching between complex loads and real source impedances but does not consider frequency-dependent load.…”

“…Dual-band transformers using stubloaded transmission line [16], T-section network [17], and dual-band line with different characteristic impedances [18] find utility in dual-band power amplifier design. A lumped components based dual-band impedance transformers was also reported [22], but it had inherent weaknesses as the operating frequency increased [6]. Recently, coupled lines have been utilized in matching complex load impedances to real source impedance [19][20][21]23].…”

A T-Section Dual-Band Matching Network for Frequency-Dependent Complex Loads Incorporating Coupled Line With Dc-Block Property Suitable for Dual-Band Transistor Amplifiers

“…Usually lumped component based matching networks [22] are simpler, but fabrication of lumped component is difficult at higher frequencies and maintaining their value over a wide frequency range is extremely difficult [23]. Furthermore, few coupled line based dual-band impedance transformers exhibiting good performance have been reported and in general they may or may not provide inherently DC blocking [24][25][26].…”

A Tri-Band Impedance Transformer Using Stubbed Coupling Line

“…However, it can only design to match purely imaginary loads. In recent years, researchers further focus on the areas of increasing the operating bandwidth and matching a complex impedance load [26][27][28][29].…”

“…Impedance transformers are one of the important components applied in microwave and millimeter-wave circuits, such as microwave amplifiers, power dividers, mixers, the feeding networks for a smart antenna array [1][2][3][4][5][6][7][8][9][10][11][12]. The quarter-wavelength transmission line (TL) is a conventional basic impedance transformer designed to operate at a single band.…”