A W-band coherent stepped-frequency pulsed radar front-end is developed. It consists of a millimetre wave transmitting source, a mm-wave local source, a DDS with multi frequency points output and two microwave sources serving as local oscillators. All the sources are coherent with the 120 MHz referenced crystal oscillator. The mm-wave sources are realized by frequency multiplier chain, up-conversion and injection locking. The phase noise of fundamental-wave injection-locked W-band harmonic Gunn oscillator output signal achieves −98 dBc/Hz at 10 kHz offset and the spurious output is less than −50 dBc. The received intermediate frequency signal is also presented.
Figure. 1. Block of Memory polynomial model.
II. MODEL DESCRIPTIONFor digital modulation signal, we assume x(t) to be the complex envelope of the input signal and yet) to be the complex envelope of output signal. Taking into consideration of AM-AM and AM-PM effect, the relation of envelopes of input and output signal can be written as following:analysis, because parameters of these models can be extracted directly by time domain methods.For wide-band communication system, the tradition nonlinear model can not accurately predict the output characteristic of power amplifier because of memory effect. The Volterra series, which can be looked as polynomial with memory, has bothered researchers for lon~time because of its complexity and convergence problems ], and many new models has been reporte&8-9]. In this paper, an envelope Memory polynomial (MP), which can be described as the simplest structure of Volterra series model in envelope domain, as shown in Fig. I, is introduced. Comparing to tradition Volterra model, MP model greatly reduces the number of the model coefficients and lowers the difficulty of parameter extraction, while it still keep ability to describe memory effect of power amplifiers.
(I)yes) yet) =F(r(t)) exp[iaJlfl(r(t)) +j{O~(t)]
x(S)o------t----lAbstract-In this paper, an envelope Memory polynomial (MP) model is introduced to describe dynamic input -output characteristics of RF power amplifiers. In the modeling approach, we use a new truncation method and an established nonlinear time series method to determine model structure. Then, we discuss the process of model parameter extraction in detailed. Finally, a 2W WCDMA power amplifier is measured to verify the performance of EH model, and good agreement between model output and measurement result shows our model can accurately predict output characteristic of the power amplifier.
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