A CMOS wideband mixer for Direct-Conversion Receivers (DCRs)

This paper presents the design and analysis of a Mixer in 0.13-μm RFCMOS process for Direct-Conversion Receivers (DCRs), with RF input frequency ranging from 50 MHz up to 6.5 GHz. This circuit has been designed to provide an intermediate input impedance, being suitable for either direct antenna connection or integrated with a LNA. This mixer attends the necessary requirements of a cognitive radio (CR), including wideband operation along with good linearity. It is based on a Gilbert-cell using the current bleeding technique with two series resonating inductors. It has a measured conversion gain of 16 dB, a measured input third-order intercept point of -1 dBm, a simulated noise figure of 8.5 dB at 1 MHz, while consuming only 4.5 mW of dc power.