Research On Multi-mode And Multi-band Power Amplifiers

With the rapid development of diverse wireless communication standards, all components of the radio frequency(RF) transmitter are required to deal with different modes and bands signals. As one indispensable component of the RF transmitter, power amplifier, which is responsible for transforming small power signal to a large one, is also demanded to deal with different modes and bands signals as its characteristics are related to the working frequency. The multi-mode and multi-band power amplifier is designed to concurrently amplify multi-mode and multi-band signals. According to the signals distribution, the multi-mode and multi-band power amplifier can be divided into two categories: the broadband power amplifier and the multi-band power amplifier. The broadband power amplifier is a better choice when the signals are distributed in one octave and the multi-band power amplifier is preferred when the signals are distributed beyond one octave. The main concerns and innovations of this thesis are these two kinds of power amplifiers and organized as following four parts.1. Analysis of the inverse class-E power amplifier at sub-nominal condition. The load impedance of the inverse class-E power amplifier will change over a certain range in practical applications. On this situation, the inverse class-E power amplifier works with only the zero current switching(ZCS) condition. In order to distinguish the conventional inverse class-E power amplifier, which works with both ZCS and zero current derivative switching(ZCDS) conditions, the inverse class-E power amplifier with only the ZCS condition is termed as the inverse class-E power amplifier at sub-nominal condition. The performance of the inverse class-E power amplifier at sub-nominal condition is analyzed in this thesis and the result shows that the inverse class-E power amplifier at sub-nominal condition is still with 100% theoretical drain efficiency. As the ZCDS condition has been removed, the inverse class-E power amplifier releases a new design parameter, which increases the design freedom. Considering that the duty ratio will affect the performance of inverse class-E power amplifier, the inverse class-E power amplifier at sub-nominal condition for any duty ratio is investigated to understand its mechanism. The analysis results show that the theoretical drain efficiency of the inverse class-E power amplifier is100%. In order to verify the proposed power amplifier, an inverse class-E power amplifier at sub-nominal condition for 0.4 duty ratio is designed in the Win Semiconductor 0.1 m GaAs p-HEMT substrate. The simulation results agree with the theoretical results. And the accuracy of the proposed inverse class-E power amplifier at sub-nominal condition is verified.2. Design procedure of the continuous class-E power amplifier at sub-nominal condition. It is proofed that the drain current falling time at the switch on-to-off instant will affect the drain efficiency of the class-E power amplifier. In order to reduce the effect of the drain current falling time at the switch on-to-off instant to the class-E power amplifier,the continuous class-E power amplifier at sub-nominal condition is investigated and presented. The continuous class-E power amplifier at sub-nominal condition, which means it only work with zero voltage switching condition, can deliver 100% theoretical drain efficiency over a broad bandwidth by adjusting the fundamental and second harmonic impedances. Comparing with the traditional broadband class-E power amplifier which is based on the admittance compensation technology, the continuous class-E power amplifier at sub-nominal condition has more design freedom.3. Broadband power amplifier. When all the concerned signals distributions are in one octave, the broadband power amplifier is a better choice. Firstly the bandwidth of the inverse class-E power amplifier is broadened by reactance compensation technology.Considering that the broadband inverse class-E power amplifier is most likely used in integrated circuit, two kinds of power amplifier for base-station are also introduced: the extended continuous class-F power amplifier and the least-losses Chebyshev broadband power amplifier. The current and voltage waveforms of the continuous class-F power amplifier are investigated at the transistor’s current-generated plane. It is discovered that the continuous class-F power amplifier can only maintain high-efficiency in one-octave.An improving bandwidth method for continuous class-F power amplifier is proposed.And a 0.4-2.3 GHz broadband and high-efficiency power amplifier is designed and measured to verify the proposed design methodology. Also, a novel broadband impedance matching technology based on the least-losses Chebyshev matching is introduced. The application of the traditional least-losses Chebyshev broadband matching is limited as the using of the Norton transformer, which will bring in the unrealistic negative capacitor. The presented method avoids this disadvantage and broadens the application range of the least-losses Chebyshev broadband matching technology. The gain ripple of the power amplifier based on this method is in 1 dB.4. Concurrent dual-band and tri-band power amplifier. When all the concerned signals distributions are beyond one octave, the concurrent multi-band power amplifier is preferred. A Π-type dual-band impedance transformer is introduced to transfer two irrelevant complex sources impedances to two irrelevant complex loads impedances at two arbitrary frequencies. Traditional dual-band impedance transformer with similar function needs to solve a quartic equation and manually select the proper solutions, which is not suitable for CAD design. The proposed Π-type dual-band impedance transformer overcomes this drawback. Also, an optimization approach based on the transducer power gain function for multi-impedances matching technology is introduced and finished by the improved particle swarm optimization(PSO) algorithm. Both the matching network of the dual-band and tri-band power amplifier are designed by this optimization approach. The dual-band power amplifier is designed with harmonic impedance controlling technology and the tri-band power amplifier is based on the continuous class-E power amplifier. The measurement results show that both the dual-band and tri-band power amplifier can work with high drain efficiency.