A novel approach to negative feedback in RX front-ends

A new approach to negative feedback is proposed and applied to active mixer cells based on Gilbert multiplier. The feedback can be exploited in several ways, and different configurations are derived. A dual-loop topology provides a solution for inductor-less broad-band receiver stages. The nature of the dual loop ensures controlled gain and input matching, and a first-order linearity analysis is presented. A single-loop narrow-band topology is derived from more traditional implementations; main characteristics are examined thoroughly, with specific respect to input matching, noise and stability issues