LTV Circuit Modelling Techniques for System Simulation. Application to a MMIC K-Band I-Q Signal-Modulator

A technique for modelling LTV circuits with frequency-translation such as mixers and signal modulators is presented. The time and frequency-domain simulations of these comp lex circuits can be very expensive in terms of computational resources. A black-box reduced modelling approach for system simulation is proposed. The model consists of an equivalent linearized low-pass filter followed by a memoryless multiplication. The reduced model provides a noticeable decrease of simulation time, with a slight loss of accuracy. The modelling technique has been applied to a MMIC QPSK signal-modulator in K band and implemented in a standard simulation tool. The simulation results of the reduced model and the complete modulator equivalent circuit have been compared, obtaining good agreement.