Acoustoelectric Amplifier Model Using Coupling of Modes and Charge Control Analysis

This article develops a novel theoretical and modeling approach for a surface acoustic wave (SAW) acoustoelectric amplifier applicable to thin-film overlay resistive or semiconductor material that is within or outside the acoustic path. The theory is developed for a direct-coupled SAW and a thin-film resistive interaction layer. The analysis uses the combination of coupling of modes and charge control analysis to develop a complete model describing the small-signal operation and the large-signal saturation effect. The model is developed for the case of direct coupling of thin films in the propagation path or coupling electrodes either inside or outside the propagation path. The approach describes the phenomenological physics and amplifier's key parameters. Predictions are compared to previously published experimental results on lithium niobate using a monolayer graphene film that yielded continuous-wave operation and a net terminal gain.