The feedthrough of the input driving signal is caused by the gate–drain capacitance; this capacitance is not included in the analysis of this paper. The gate–drain capacitance is nonlinear and dependent on the gate–drain voltage [27]; it can, therefore, affect the amplifier performance like the nonlinear output capacitance. The gate–drain capacitance is usually low when compared to the transistor output capacitance; the gate–drain capacitance of the LDMOS transistor MRF21010, for example, is about 1 pF. In some cases, the effects of the gate–drain capacitance can be neglected; on the other hand, because the driving power of the class-E switch-mode amplifier is usually high, the feedthrough is comparatively stronger than the desired output power at low drain voltage. The feedthrough strongly affects the
linearity of the dc supply modulation of the class-E amplifier and must be taken into consideration for low power operation mode. From the simulation results and the following measured results, though, the feedthrough can be neglected for moderate output power. The drain efficiency degradation in this range is mainly caused by the transistor output capacitance; the effects of the gate–drain capacitance are, therefore, not included. For
precise analysis, especially at the very low drain voltage, thegate–drain capacitance cannot be neglected, as shown in the simulations and measurements of this experiment.
The feedthrough of the input driving signal is caused by the gate–drain capacitance; this capacitance is not included in the analysis of this paper. The gate–drain capacitance is nonlinear and dependent on the gate–drain voltage [27]; it can, therefore, affect the amplifier performance like the nonlinear output capacitance. The gate–drain capacitance is usually low when compared to the transistor output capacitance; the gate–drain capacitance of the LDMOS transistor MRF21010, for example, is about 1 pF. In some cases, the effects of the gate–drain capacitance can be neglected; on the other hand, because the driving power of the class-E switch-mode amplifier is usually high, the feedthrough is comparatively stronger than the desired output power at low drain voltage. The feedthrough strongly affects thelinearity of the dc supply modulation of the class-E amplifier and must be taken into consideration for low power operation mode. From the simulation results and the following measured results, though, the feedthrough can be neglected for moderate output power. The drain efficiency degradation in this range is mainly caused by the transistor output capacitance; the effects of the gate–drain capacitance are, therefore, not included. Forprecise analysis, especially at the very low drain voltage, thegate–drain capacitance cannot be neglected, as shown in the simulations and measurements of this experiment.
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