Design of the Class-E Power Amplifier with Finite DC Feed Inductance under Maximum-Rating Constraints

Abstract

This paper proposes an analytical expression set to determine the maximum values of currents and voltages in the Class-E Power Amplifier (PA) with Finite DC-Feed Inductance (FDI) under the following assumptions—ideal components (e.g., inductors and capacitors with infinite quality factor), a switch with zero rise and fall commutation times, zero on-resistance, and infinite off-resistance, and an infinite loaded quality factor of the output resonant circuit. The developed expressions are the average supply current, the RMS (Root Mean Square) current through the DC-feed inductance, the peak voltage and current in the switch, the RMS current through the switch, the peak voltages of the output resonant circuit, and the peak voltage and current in the PA load. These equations were obtained from the circuit analysis of this ideal amplifier and curve-fitting tools. Furthermore, the proposed expressions are a useful tool to estimate the maximum ratings of the amplifier components. The accuracy of the expressions was analyzed by the circuit simulation of twelve ideal amplifiers, which were designed to meet a wide spectrum of application scenarios. The resulting Mean Absolute Percentage Error (MAPE) of the maximum-rating constraints estimation was 2.64%.

Analysis of the Soft-Switching Tuning Effect on the Figures of Merit Involved in the Design of a Class-E Amplifier with Finite DC-Feed Inductance

“…This ideal soft-switching behavior is shown in Figure 2. The design of the class-E PA has been explored in several works [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. From the point of view of the L SH element, the class-E PA can be divided into two topologies: class-E PA with RF choke [9][10][11][12] and class-E PA with finite DC-feed inductance (FDI) [13][14][15][16][17][18][19][20][21][22][23][24].…”

“…The design of the class-E PA has been explored in several works [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. From the point of view of the L SH element, the class-E PA can be divided into two topologies: class-E PA with RF choke [9][10][11][12] and class-E PA with finite DC-feed inductance (FDI) [13][14][15][16][17][18][19][20][21][22][23][24]. The model of a class-E PA with RF choke assumes a DC input current, which simplifies the mathematical analysis and allows its design through simple analytical equations [9,12].…”

“…However, the finite feed inductance increases the designer's degrees of freedom. For instance, the designer of a class-E PA with FDI must optimize the component combination to achieve the design specifications and restrictions with high-efficiency [23,24]. Additionally, FDI is particularly useful in applications with size constraints, because it allows inductors to be reduced in size [18,21].…”

“…Commonly, the PA design starts with the calculation of the initial circuit component values through design equations [9,12,19,[22][23][24]26]. However, these equations only provide an approximation of the nominal class-E operation (i.e., ZVS and ZVDS) because of the parasitic elements.…”

“…However, these equations only provide an approximation of the nominal class-E operation (i.e., ZVS and ZVDS) because of the parasitic elements. A common solution to guarantee the soft-switching operation with parasitic elements is component tuning [10,12,21,23,24,[27][28][29]. However, and to the best of the authors' knowledge, this method has not been analyzed in class-E PAs with FDI topology.…”