Highly integrated Active Dual Response Filter

This work focuses on the design of a novel compact Active Dual Response Filter within a single device which allows ensuring the coexistence of three different standards while proposing an optimal structure in terms of response and space. The proposed filter is based on a highly selective low-pass filter at which a highly integrated compact notch filter is coupled. This co-integration of both filters is not a cascade so that the dual response filter occupies the same area as the low-pass filter alone. The Notch filter is set to 700 MHz and is loaded by an Active Capacitor (AC) circuit that allows a rejection at the notch central frequency of at least 19 dB. The low-pass filter cut-off frequency is Fc =890 MHz, the in band return loss is better than 20 dB. This methodology can be extended to various shapes of filter functions.