On the SFDR performance of BJT RF circuits, an analytical approach

A simple analytical approach for nonlinear distortion in RF bipolar circuits is utilized in the evaluation of spurious free dynamic range (SFDR) in BJT circuits. Simple closed-form expressions can predict the critical bias conditions corresponding to minimum or maximum SFDR. This method is applied to low noise amplifier (LNA) and single balanced mixer (SBM) circuits to study and optimize the dynamic range. The proposed method can predict the dynamic range with less than 10% error in most cases. The validity of this technique is examined by comparing the results of SPICE simulations to the calculations of the proposed method under different operating conditions.