This paper describes bifurcation phenomena of a photovoltaic system. The studied photovoltaic (PV) system includes a solar panel, a boost converter, a maximum power point tracking (MPPT) controller and a storage device. Computer simulations are performed to capture the effects of variation of some chosen parameters on the qualitative behavior of the system. The impact of the maximum power point (MPP) current and voltage variations due to luminosity changes is determinate, as well as the load variation. The stability of the system is analyzed using the state transition matrix over one switching cycle (the monodromy matrix) including the state transition matrices during each switching (the saltation matrices). This investigation is important to predict nonlinear phenomena and for the components dimensioning for a proper functioning
This paper presents a multibit sigma-delta modulator for GSM/WCDMA receivers. It uses a sigmadelta modulator with feedforward signal path to reduce the operational amplifiers nonlinearity effects. The improved performance of multibit topologies is exploited to reduce the oversampling ratio and to overcome stability limitations. A third-order 4bit feedforward sigma-delta modulator topology is chosen to meet both GSM and WCDMA specifications without needing additional hardware.Simulation results indicate that, 92-dB peak SNR is achievable over a 200kHz bandwidth, in GSM mode and 61-dB peak SNR over a 2MHz bandwidth, in WCDMA mode.
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