Compact transformer-based notch filter

Abstract

A notch filter is coupled to a first input node and a second input node, and is configured to present a capacitive load to a differential signal provided to the first and second input nodes, and to present a series-resonant inductive-capacitive load to a common-mode signal provided to the first and second input nodes. The notch filter includes a transformer and a capacitor bank. The transformer includes a first winding having a positive-polarity terminal coupled to the first input node and a second winding having a positive-polarity terminal coupled to the second input node. The capacitor bank includes a first capacitor coupled between a negative-polarity terminal of the first winding and a bias node, and a second capacitor coupled between a negative-polarity terminal of the second winding and the bias node. The first and second capacitors may be variable capacitors.

Dependencies are inferred from the claim text.