Two integrated bandpass filters have been designed and fabricated on standard 130 nm CMOS technology. The lumped element, third-order Butterworth bandpass filters at 9.45 and 1.75 GHz are designed for sub-band filtering in a spectrum monitoring receiver function in a future cognitive radio. A series coupled resonator topology is selected and a novel delta–star transformation technique is applied to obtain element values suitable for reliable fabrication on an integrated circuit. Occupying die areas of 780×200 µm and 1750×500 µm each, the filters achieve insertion losses of 15.6 and 8.6 dB, and bandwidths of 1 GHz and 210 MHz, respectively, which are suitable for the chosen spectrum monitor receiver architecture.