An alternate adjacent channel interference (AACI) filter is integrated into an intermediate frequency (IF) channel select filter to filter received RF signals. The IF channel select filter is an IF staged structure comprising successive IF stages. Each of the successive IF stages is a 2-biquad integrator. The AACI filter is integrated into the first IF stage of the IF channel select filter by re-using circuit components such as an operational amplifier, an input resistor, and a shunt capacitor of the first IF stage. The shunt capacitor is coupled between a middle point of the input resistor and ground. The AACI filter is realized via different equivalent implementations of the re-used circuit components of the first IF stage. A value of the shunt capacitor of the AACI filter becomes a fixed-value when a value the input resistor is inversely proportional to the bandwidth of the AACI filter.