Prakash Bhartia

A Low-Loss Voltage-Controlled Analog Phase-Shifter Using Branchline Coupler and Varactor Diodes

This paper proposes a new type of continuously tunable voltage-controlled analog phase shifter for radio frequency and microwave-frequency applications. The design uses a branchline coupler and two varactor diodes. The concept has been tested at 900 MHz using FR4 dielectric material using thin-film microstrip technology. The measured phase shift variation is 115 degree over the entire range of the control voltage. The measured insertion loss is typically better than 1.5 dB and the measured return loss is better than-15 dB. The performance can be further improved by using lower-loss dielectric materials. The design is also scalable to other frequency bands.

A simple interstage matching technique for designing hybrid microwave power amplifiers

A non-50-/spl Omega/ interstage matching technique has been used for designing multistage microwave power amplifiers. The technique is especially relevant to cases where the final stage uses an LDMOS device whose dynamic input impedance is extremely low and is best matched directly (without first translating to 50 /spl Omega/) to the output of the previous stage. A specific example is presented. The concept, however, is quite general and will be of interest to the RF design community at large.

The use of 3D electromagnetic simulation tools in the design of Microwave Integrated Circuits: An accuracy assessment

The accuracy of well-known commercially available 3D electromagnetic simulation tools has been examined through designing, building, and testing several original Microwave Integrated Circuits. It turns out that the accuracy of the tools considered is acceptable for most practical purposes, for frequencies up to 3GHz (upper limit of our investigation).

Microwave Power Amplifiers for Satellite Communication Systems

This paper provides a short review of radio frequency/microwave power amplifiers (PAs) and their critical role in a modern satellite communication system.

Microwave power amplifiers for satellite communication systems

This paper provides a short review of radio frequency/microwave power amplifiers (PAs) and their critical role in a modern satellite communication system.

Design and analysis of low pass microstrip filters using MATLAB

A MATLAB-based CAD algorithm for analyzing stepped-impedance microstrip low-pass filters is reported. The algorithm uses a circuit theory approach based on ABCD parameters of the individual microstrip lines. The accuracy of the algorithm is verified for two widely-different practical examples, against data obtained using the ANSYS/ANSOFT circuit simulation tool and the HFSS simulation tool. The agreement among the three sets of data is found to be quite good. It is concluded that the use of MATLAB is a useful alternative for designing microstrip low-pass filters with stepped-impedance resonators.

Matlab-based accurate dispersion models for unshielded suspended microstrip

Suspended microstrip, shown in Fig.1 (unshielded case) and Fig. 2 (shielded case), is a very useful variation of the conventional microstrip structure. This transmission line is created by introducing an air-gap between the ground plane and the substrate, as shown in Figs. 1 and 2. The main advantages of this type of microstrip, over the conventional microstrip, follow.