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This paper discusses the possibility of applying quad-phase surface acoustic wave (SAW) filters to a power divider/combiner for RF power amplifiers (PAs). First, it was shown that the quad- phase SAW filter is equivalent to a quadrature hybrid with embedded balun and filter functions. Then, the device is applied for a PA configuration where four amplifiers are sandwiched in between two quad-phase...
Future generations of wireless communications are expected to place increasing burdens on the efficiency and linearity of power amplifiers, due to the use of more complex multi-carrier waveforms and OFDM. This has implications for the design of transmitters in portable/mobile devices as well as base stations and access points. This paper will summarize the digital predistortion techniques that can...
In this paper nonlinearities due to FET amplifiers are described by using a novel behavioral modeling approach. While our proposed method requires the identification of delays and coefficients like in a standard diagonal memory polinomial model, the importance of out-of-diagonal terms is emphasized if the amplifier exhibits memory effects. Furthermore, the different terms, delays and coefficients...
This paper studies the sources of the short term memory effects exhibited by radiofrequency power amplifiers. Based on this study a multi-branch structure-based predistorter was applied to overcome the inability of the traditional predistortion to compensate for these imperfections. In addition, the identification of the parameters of such structure is investigated and several adaptive algorithms...
Power amplifiers are important blocks in communication systems and their efficiency and linearity are critical performance parameters. In this paper, we present a preliminary investigation into RF feedback systems designed to improve the efficiency-linearity trade-off for power amplifiers. We demonstrate very large potential improvement in trade-off due to feedback and significant actual improvement...
A nonlinear auto-regressive moving average (ARMA) structure capable of compensating nonlinear memory effects in RF power amplifiers is here presented. Results on the linearity improvement, in both in-band and out-of-band distortion compensation, achieved by this baseband digital predistorter are provided. Moreover, a study on this nonlinear ARMA system stability is also reported.
This paper proposes a polar function linearizer to reduce the spectral regrowth of radio frequency power amplifier using even order harmonic signals. An AM modulator, modulate fundamental signal with even order harmonic signals, makes inverse transfer function of power amplifier and controls amplitude and phase of them with polar function factors. As a result, this polar function linearizer is suppressed...
A quad-band GSM/GPRS power amplifier module is designed with a built-in ability of RF power transmitting control. Within the RF power transmitting control loop, a RF power detecting circuit with another reference circuit are embedded together onto the same InGaP/GaAs HBT power amplifier chip to achieve a good temperature compensation. Such power chips are then assembly with a silicon CMOS comparative...
Traditional radio frequency bi-directional amplifiers rely on switches with their associated increase in cost, size and loss to achieve time division duplexing. A switchless bi-directional amplifier is proposed whereby the power amplifier (PA) and low noise amplifier (LNA) are connected directly in an anti-parallel configuration. Experimental results show that there is no gain degradation when compared...
In this paper, a novel closed-form expression of the intermodulation distortion (IMD) of nonlinear RF power amplifier (PA) considering input and output frequency responses is proposed. A transmitter including nonlinear PA is modeled with three-box (Wiener-Hammerstein type) model to include input and output frequency responses. To verify the closed-form expression of IMD, the analytical results are...
A precise modeling method for thermal memory effect has been proposed. The proposed method consists of a multi-stage thermal RC-ladder network, which has been replaced from heat diffusion equation. Different from conventional method, the proposed method is valid for both steady state solutions and transient solutions. As examples, output voltage transient phenomena and 3rd order inter modulation distortion...
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