Analysis of a Broadband High-Efficiency Switch-Mode /spl Delta//spl Sigma/ Supply Modulator Based on a Class-E Amplifier and a Class-E Rectifier

In this paper, a broadband high-efficiency supply modulator is proposed. This modulator, with a node controlled by ΔΣ modulator´s output, consists of a conventional Class-E amplifier and a Class-E rectifier. The configurations and operation principles of this modulator are introduced to explain the envelope reconstruction process. The performance of this modulator in steady state is analyzed to show the reason for high-efficiency operations assisted by a shunt diode, especially for short-circuited load resistance. Its performance for broadband envelopes amplification is analyzed using numerical difference equations. The results show that efficiency degradation and nonlinearity of this modulator are inevitable due to transient responses. The most significant factors related to the performance degradation, such as switch loss and conduction loss, are determined and verified by numerical simulations. The simulations for one-carrier wavelength code-division multiple-access (WCDMA) envelopes show that over 80% average efficiency and normalized mean square error (NMSE) of -16 dB can be obtained in numerical examples even considering the nonidealities. An experimental supply modulator is given to verify the proposed modulator. In this experiment, 48.6% average efficiency and NMSE of -15.9 dB are measured for WCDMA envelopes of 6.1-dB peak-to-average-power ratio.