Mohammad A. Maktoomi

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

This paper reports design of a new dual-band T-type impedance transformer also exhibiting DC-blocking feature. The design aims at achieving matching for frequency-dependent complex loads having distinct values at two arbitrary frequencies to Zs (here, 50›). A step-wise analysis on the developed dual-band impedance transformer provides simple closed-form design equations. The design is verifled by simulation in Agilent ADS. For experimental veriflcation a PCB prototype is fabricated using FR-4 material, operating at 1.45GHz and 2.61GHz. A good result is obtained conflrming the theory and simulation.

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

This paper presents a dual-band impedance transformer for real source and load impedances that is capable of providing matching at two arbitrary frequencies. There are two possible configurations of the proposed technique, and both the configurations are simple and possess flexibility to cater to wide range of impedance environments. A very useful feature of the design is its inherent ability to provide DC isolation. A prototype, which works at 1 GHz and 2 GHz, fabricated using Rogers RO4350B laminate validates the proposed design with a good match between theoretical and experimental results. In addition, a dual-band T-junction power divider is reported to demonstrate the usefulness of the proposed impedance transformer.

A Dual-Frequency Matching Network for FDCLs Using Dual-Band λ/4-Lines

A new approach to design a dual-band matching network using a dual-band quarter-wave line is presented. The proposed matching network is capable of simultaneously matching frequency- dependent complex loads (FDCLs) having different values at two arbitrary frequencies to a real source impedance, Z0. A very simple step-wise design procedure is discussed for the transformer along with closed-form design equations which are very simple in nature. For experimental verification, two PCB prototypes have been fabricated using FR-4 material, operating at 1 GHz and 2.42 GHz. The measurements results matches well with that obtained from simulation, exhibiting good performance.

Improving Load Range of Dual-Band Impedance Matching Networks Using Load-Healing Concept

A novel and very simple scheme to mend conventional dual-band impedance matching networks is presented. It involves the employment of a load-modifying element (load-healer) so as to extend the range of frequency-dependent complex load that could be matched. Two simple load-healers incorporated in the conventional T-network are used to illustrate the concept. The proposed scheme can be successfully applied in many situations where conventional matching networks are severely limited. Two prototypes operating concurrently at 1 and 2 GHz are designed corresponding to the two types of load-healer. They are implemented on FR4 substrate having a dielectric constant of 4.6, a substrate height of 1.5 mm, and a 35-

Theory and Design of a Novel Wideband DC Isolated Wilkinson Power Divider

\mu\text{m}

A Generic Tri-Band Matching Network

copper cladding. The prototypes exhibit good agreement between their EM simulated and measured results.

A new adjustable square/triangular-wave generator using CCII/CCCII and OTA

In this letter, a novel wideband 3-dB Wilkinson power divider (WPD) is presented. It employs port matching using coupled lines to achieve wider isolation bandwidth, without modifying the isolation network. Due to the presence of parallel coupled lines, the design enjoys complete DC isolation. Analysis leading to closed-form design equations shows freedom in choosing design parameters. Many design case studies are provided to show the capabilities of the proposed design. The designed and fabricated prototype shows promising results.

Systematic Design Technique for Dual-Band Branch-Line Coupler Using T- and Pi-Networks and Their Application in Novel Wideband-Ratio Crossover

A scheme to achieve impedance matching at three arbitrary frequencies is presented. The proposed matching network is cascade of a dual-band matching network and a novel dual-to-tri-band transformer. Analysis of the proposed network provides closed form design equations that enable physically realizable solution owing to the presence of a free design variable. The presented theory is demonstrated through two example prototypes on Rogers RO4350B substrate. The obtained simulated and measured results clearly exhibit the potential of the proposed design.

A Theorem for Multi-Frequency DC-Feed Network Design

A study on two new circuits to generate square/triangular waveforms are presented. Circuit-I consists of a CCII, a capacitor, an OTA and a voltage divider network. The frequency can be changed by changing the voltage division ratio or the time-constant and amplitude by a combination thereof. As an extension of this concept, in the proposed circuit-II a CCCII is used in place of CCII to get electronic control through a bias current. Again, the frequency of the waveform can be adjusted by the bias current of the CCCII or the voltage division ratio and amplitude by a combination thereof. The circuits have been fully analyzed to deduce both ideal as well as non-ideal design equations. Proposed circuits have been extensively studied using the LTspice circuit simulator and one of them is experimentally verified with components available in our lab. The measured waveforms perfectly match with the theoretical/simulated waveforms. Finally, a comparison with the recently proposed works is also included.

A dual-band impedance transformer for frequency-dependent complex loads incorporating an L-type network

In this paper, a generalized analysis and design methodology of a dual-band branch-line coupler (BLC) is presented. The proposed design, although based on the prevalent method of replacement of various arms of a single-band BLC with an equivalent T-/Pi-network, simplifies the design approach by only replacing either pair of arms and therefore provides four distinct topologies. Closed-form design equations along with insightful comments are reported for all the four topologies of the BLC. A number of cases are investigated to demonstrate the effectiveness of the proposed design for equal and unequal power division ratio and band-ratio (= f2}/f1 ). As an application, a novel dual-band crossover as a cascade of BLCs is also presented. While investigating the limitations of previous designs, a strategy to obtain the crossover with so far the widest band-ratio and simple layout is also presented. An unequal power division dual-band BLC and a dual-band crossover are designed which operate at 1/2 and 1/4 GHz, respectively. These designs are validated from the electromagnetic simulations and prototypes implemented on RT/Duroid 5880 substrate.