The hybrid pi model of the bipolar transistor is a popular model used for small signal modeling of the bipolar. A paper released by Signal Processing Group describes the components that constitute the model and presents first order expressions for their calculation. The paper is available for free on the Signal Processing Group website and can be accessed from the “complementary” menu. Please visit. In addition a javascript calculator is planned for release from Signal Processing Group that can be used by a user to make the calculations easier.