Time-Domain Numerical Simulation of Electronic Circuits and Surface Acoustic Wave Devices Using Their Admittance Parameters

We present a method to calculate the transient response of electronic circuits when these contain elements whose behaviors are given by their admittance matrices in the frequency domain. After describing this method in detail, an amplifier with resistive networks and interdigital transducers using specific input signals was proposed to test the method, and these results agreed when compared with those obtained with a simulation program with integrated circuit emphasis (SPICE)-based program. Besides, the simulation of two oscillators are presented; the first has a feedback network consisting of serial-connected equivalent circuits of crystals, and the second uses a feedback network with a surface acoustic wave (SAW) delay line. For the first oscillator, the waveforms obtained using this method and a SPICE-based program considering two different numerical integration methods were compared, and they looked similar, but all signals have different rise times because these simulations are very sensitive to inherent numerical errors. The simulation of a SAW delay line oscillator and its input and output voltages and currents were obtained, and its fundamental frequency was 77.77 MHz. These simulated results were validated experimentally through the oscillation frequency, which was found using the $-parameters of the amplifier and the delay line and an oscillation criterion, and it was measured directly in the circuit. The experimental oscillation frequencies were 76.9 and 77.5 MHz, respectively, and the errors between simulation and experimentation were approximately 1%.