Design of broadband and high‐efficiency class‐E amplifier with pHEMT using a novel low‐pass microstrip resonator cell

Abstract

2.88 GHz. For the lower mode with C ¼ 0.6 pF and the higher mode with C ¼ 5 pF, the effects of varying / on CP performance are given in Figures 4 and 5, respectively. The simulation results suggest that an axial ratio of less than 2 dB can be found when / ranges between 10 and 25 for the lower mode and between 12 and 16 for the higher mode. RECONFIGURABLE DESIGN AND EXPERIMENTAL RESULTSAn antenna prototype with electrically switching was realized using a varactor diode (BB837, Siemens Semiconductor Group). For the dc bias (V 0 ) used for controlling the varactor, its positive is connected to the feed line through a RF choke, which is composed of a high-impedance meandered microstrip line and a grounded capacitor of 1 nF, and the negative is directly linked to the RF ground plane, as shown in Figure 1. Figure 6 exhibits the experimental results when V 0 is switched between two different values. From the measured results, it can be seen that the frequency with minimum axial ratio is 1.83 GHz for the case of V 0 ¼ 28 V and it is 2.96 GHz for the case of V 0 ¼ 6 V. The CP bandwidths, determined by 3 dB axial ratio, are 2.7 and 3.3% at the lower and higher CP operating frequencies, respectively. In addition, Figure 6 also demonstrates that a return loss of less than 10 dB is achieved within the two CP bandwidths. Therefore, the antenna can perform the dualfrequency operation with a frequency ratio of about 1.6 through switching.The radiation patterns at 1.83 and 2.96 GHz are measured and their results are plotted in Figure 7. Broadside radiation with good CP performance is observed for each operating frequency, and the polarization in the plane of z > 0 is left-handed. The peak gain at 1.83 GHz is about 3.3 dBic and it is merely 0.2 dB lower than that at 2.96 GHz. CONCLUSIONA design for circularly polarized annular slot antennas with switchable frequency has been presented. Only one diode is required in the reconfigurable design. With controlling the dc bias of the diode, the antenna can perform dual-frequency operation with a high frequency ratio. Moreover, the antenna at the two operating frequencies has almost the same radiation pattern, polarization performance, and peak gain.ABSTRACT: In this article, a high-efficient class-E amplifier design with low voltage and broadband characteristics using a novel Front Coupled Tapered Compact Microstrip Resonant Cell is presented. The proposed micorstrip resonator is used as the harmonic control network in order to suppress higher order harmonics, which obtained the optimized impedance matching for the fundamental and harmonics. The class-E amplifier is realized from 0.7 to 1.8 GHz, and obtained the power added efficiency of 72.5-77.5%. The maximum value of Power added efficiency (PAE) is 79.7% with 11-dBm input power at 1.5 GHz. The designed class-E amplifier using the proposed harmonic control network gained 15.34% increment in PAE, and 25.6% reduction in the circuit size in comparison with the conventional class-E amplifier. The simulation and measurement results show th...

Modeling and analysis of class-E zero-voltage switching amplifier at any grading coefficient and duty ratio

“…[15] Moreover, high-efficiency performance remains as the main requirement for the power amplifier in microwave applications, [16,17] and the class-E power amplifier has considerable performances for microwave and biomedical applications. [18,19] It can be concluded from the mentioned discussions that it is valuable to derive the analytical expressions for the class-E power amplifier with the class-E sub-nominal operation at any grading coefficient m and duty ratio D. In this case, the degree of the design freedom increases by two in the comparison with the class-E ZVS amplifier with the linear shunt capacitance and the MOSFET nonlinear drain-source capacitance for the fixed grading coefficient.…”

Design of class-E power amplifier for zero-current switching operation with MOSFET nonlinear output parasitic capacitance

“…The class‐E power amplifier with the nominal conditions has been widely used for the RF and microwave applications , and many power electronic amplifier's applications . In these applications, the peak switch voltage and current of the active device is the main challenge, which is required to be solved due its wide applications.…”