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Abstract: This article presents a highly linear balanced power amplifier with miniaturized quadrature hybrid coupler for carrier aggregation (CA). The miniaturized quadrature coupler is designed using a novel U‐shaped transmission line (USTL) concept to achieve good size reduction. The novel branch‐line coupler is used to design a wideband balanced PA. The performance of the balanced PA is compared to a single PA solution. The balanced PA shows better performance with improved matching properties and better electrical stability. There was an increase in saturated maximum output power (Pout) from 8 dBm for the individual PA to 13.41 dBm for the balanced with a power‐aided efficiency (PAE) of 43.92%. The highly linear balanced PA achieves a 14 dB ACPR reduction and also improves ACPR by 12 dB for noncontiguous and 9 dB for contiguous carrier aggregation. [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents applications of reconfigurable matching networks for RF amplifier design. Two possible solutions are given, one where the switching element is a PIN diode, and the other is based on graphene. Due to the fact that its conductivity depends on applied bias voltage, the graphene-based circuits can be used in microwave circuits as controllable elements. The structure of the proposed switch is very simple and it is particularly convenient for microstrip-based circuits. Because of that, a design of reconfigurable amplifier with the graphene-based switch is presented together with the one which has the PIN diode switch. Both amplifiers have the same specifications, and the one with the PIN diode switch is fabricated. The amplifier utilizing the PIN switch was used as a reference to make a comparison the two types of switches. Results of both amplifiers are very similar which indicates possible future applications of the graphene-based switch. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1487-1491, 2015 [ABSTRACT FROM AUTHOR]

The linearization technique that uses simultaneous injection of the second harmonics into the amplifier input and their feedforwarding to the amplifier output is suggested. This technique reduces the third-order intermodulation products in multichannel amplifiers when amplifiers operate closer to saturation. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007. [ABSTRACT FROM AUTHOR]

A linearization technique that uses the injection of the fundamental signal second harmonics together with the fundamental signals at the amplifier input has been improved in this paper by introducing phase correction of the fundamental signals according to the differences in phases of the second harmonics. As the result, the improvement in third-order intermodulation power levels is approximately 40 dB for analog and 22 dB for digitally modulated signals for multichannel applications. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 150–153, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11000 [ABSTRACT FROM AUTHOR]

A difference frequency technique for reducing the IM product levels in a nonlinear RF amplifier is presented. The technique is based on the standard two-tone test. The two sinusoid signals together with their difference frequency signal are fed into the amplifier. CAD simulation shows that the third-order IM level at the output of a nonlinear amplifier can be reduced using this technique. The results of a related experiment are reported, which gave a measured of 50 dB reduction in the level of the third-order intermodulation without affecting the fundamental power levels. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 24: 208–210, 2000. [ABSTRACT FROM AUTHOR]