In this paper, a nonlinear model of a commercial 10-W laterally diffused metal oxide semiconductor (LDMOS) transistor for FM transmitters is identified. It is based on high-frequency small-signal measurements for the
identification of both the parasitic network and the strictly nonlinear dynamic effects, whereas low-frequency large-signal measurements are exploited for the description of the dynamic I/V characteristics of the device above the cut-off of low-frequency dispersion. A validation of the proposed model is provided by using time-domain nonlinear measurements carried out at 40MHz and 100 MHz
The term waveform engineering denotes all those circuit design techniques that are based on shaping the transistor voltage and current waveforms. From a general perspective, these design techniques can be grouped in two main categories according to the adopted design tool: measurement- and model-based. In the last two decades, thanks to the proliferation of setups enabling calibrated waveform acquisition at microwave frequencies, waveform engineering has attracted continuously increasing interest in the microwave engineering community. In this article, a comprehensive analysis of the waveform-engineering based design techniques is reported, paying particular attention to the advantages and drawbacks associated to each approach
In this paper we apply for the first time the nonlinear-embedding technique to the design of power amplifiers based on laterally-diffused metal-oxide-semiconductor (LDMOS) field-effect transistors (FETs). Such a design technique is based on setting the transistor load line at the intrinsic current-generator plane, according to well-known theoretical guidelines. Then, the selected operating condition can be transposed at any design frequency at the extrinsic transistor terminals, by means of a model of the device nonidealities, such as the nonlinear intrinsic capacitances and the linear parasitic effects. A harmonicallytuned high-efficiency class-F and a wideband class-AB power amplifiers operating within the FM broadcasting band 88 ÷ 108 MHz based on a 10-W LDMOS are then designed and realized. To definitely assess the validity of the proposed approach for the LDMOS technology, we compare the measured performance on the fabricated power amplifiers with the expected predictions.
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