Papers by Keyword: Power Amplifier

Abstract: An Ultra broadband power amplifier module based on GaN HEMT is studied. TGF2023-02 Chip of GaN HEMT from TriQuint Corporation is adopted and modeled first. The amplifier is designed with negative feedback technique. DC bias circuits and microstrip matching circuits are simulated and optimized carefully. Simulation results show that the amplifier module has a wide range frequency response from 3 to 8 GHz. It exhibits power gain of 7.6 dB, an output power of 37.5dBm under DC bias of V_ds = 28 V, V_gs = -3.6 V at the frequency of 5.5 GHz.

Abstract: Digital predistortion (DPD) is a method widely used to compensate the nonlinearity of power amplifier to improve the transmitting signals. The DPD performance, however, depend heavily on the hardware design on signal integrity, EMI and low additional distortion of downconversion circuit. In this paper, a new high-performance hardware solution for DPD is introduced. Engineering tests show that this hardware design characterizes by high reliability and excellent performance to satisfy the requirements of DPD.

Abstract: The performance of the power amplifier is closely related to their hardware components and current control modes. The work was focused on comparison of the experimental results based on different current sensors and the application of two different current control modes for 3-state amplifiers. When the same control mode was used, three kind of current sensors were tested and the corresponding amplifier current ripples were measured. Experimental results shown that when using a faster current sensor, the amplifier achieved smaller current ripples. Then a 3-state PWM current control mode and a Sample-Hold current control mode were compared based on the power amplifier circuit with the same hardware components. The performance difference in the experiments were studied and explained. The 3-state PWM power amplifier could achieve a better performance in actual use.

Abstract: Aiming at the nonlinear characteristics and memory effects of power amplifier, a memory rational function behavioral model, which based on the memory polynomial model and memoryless rational function model, is proposed. The model coefficients are identified by conjugate gradient method. The estimation of the best model nonlinearity order and the best memory depth is carried out by minimized the normalized mean squared error (MNSE). The model is validated using multi-carrier WCDMA signal and a MRF6S21140H power amplifier by measurement. The result indicates that the proposed model can achieve better model performance with less number of coefficients compared to the memory polynomial model and memoryless rational function model

Abstract: For the linearization of power amplifiers, a digital pre-distorter is proposed to compensate nonlinear distortion in this paper. The pre-distorter is realized by Volterra series, and a restarted limited memory BFGS(LBFGS) algorithm is proposed for training the nonlinear pre-distorter. Training of Volterra series can be switched between gradient descend algorithm and quasi Newton algorithm by setting a switching condition, and LBFGS algorithm can be used for high dimensional iterative matrix of BFGS algorithm. These make the new algorithm much more stable with a fast convergence rate. The pre-distorter is used for OFDM power amplifiers and it high efficiency is proved by simulation results. Moreover, the convergence rate of the proposed algorithm is greatly faster than that of the gradient algorithm.

Abstract: Based on the Gigabit Ethernet Protocol, the RF (Radio Frequency) power amplifier remote monitoring system was designed. The system collect digital signal from predistortion module, transmit the gigabit Ethernet network to outside, and improve the system efficiency. It adopts the SOPC technology hardcore and softcore, which makes the whole system realized in the single piece of chip. Softcore is the Alteras IP core--Nios II processor, design processors, make use of the custom parts and programs gigabit Ethernet transceiver and internal driving in processor. The integration and reliability of the system are in great improvement. Through testing, system function can satisfy transmission requirements of normal transceiver RF power amplifier state information and control information.

Abstract: In order to improve the efficiency of Digital TV transmitter, we uses a new type of four-stage Doherty structure. Based on the transmission line theory and active loadpull theory, we deduce the principle of the four-stage Doherty structure, and use ADS to design a four-stage Doherty power amplifier. The simulation result shows that this four-stage Doherty PA has an efficiency of 34% at 6dB back-off (53dBm) for DVB-T OFDM 64 QAM modulated signal. The ACPR and MER obtained at 53dBm when output power are 31dBc and 28dB respectively.

Abstract: A broadband power amplifier module based on GaN HEMT operating Ku band is designed. TGF2023-02 Chip of GaN HEMT from TriQuint is modeled first. And then the module consists of two stages amplifiers. The first stage amplifier is single-stage amplifier and the second is two-way combiner amplifier. Wilkinson power divider, DC bias circuits and microstrip matching circuits are simulated and designed carefully. Simulation results showed that the amplifier module exhibits a power gain of 7 dB, power added efficiency of 13.9%, and an output power of 16 W under Vds=28 V, Vgs=-3.6 V, CW operating conditions at the frequency of 15 GHz.

Abstract: This paper presented an adjustable analog predistortion linearization method for RF power amplifier. The linearization includes an attenuator, a phase shifter and an anti-parallel Schottky diode pair with DC bias, through adjusting these components, we can adjust predistortion characteristic of the linearization to be complementary to distortion characteristic of RF power amplifier. By cascading this linearization with power amplifier, we can improve linearity of amplifier. Firstly, we simulated the proposed predistortion linearization with software ADS, then the linearization was manufactured and tested together with RF power amplifier PTF080551. Experimental results show that we can adjust predistortion characteristic of the linearization to be closely complementary to distrotion characteristic of power amplifier PTF080551 as desired. After cascading the linearization with power amplifier PTF080551, more than 10dB improvement in IMD3 of the amplifier can be achieved. Furthermore, the linerarizaion is flexible and can be adjusted to linearize different amplifiers.

Abstract: A SiGe HBT power amplifier for Time Division Synchronous Code-Division Multiple-Access (TD-SCDMA) application with a single positive 3.3V supply has been demonstrated in this paper by adopting a newly proposed usage of the bonding wire. Though the emitter bonding wire may decrease the power gain, it can also decrease the effect of the knee voltage, thus increase the efficiency of the power amplifier. The post-simulation result shows that it can exhibit a linear gain of 29dB, output power of 30dBm, power-added efficiency of 38.49%, and -43dBc suppression at the second harmonic for TD-SCDMA application.