Wide bandwidth and low power CMOS mixer with high linearity for multiband receivers using direct conversion implementation

A wide bandwidth double balanced mixer implemented in CMOS technology is described and optimized. The concept of the presented mixer is that of a variable feedback amplifier, in which, resistive MOSFETs are used as feedback resistors and active MOSFETs act as amplifiers. This combination of active and resistive concepts achieves high linearity and good conversion gain. For a local oscillator (LO) power less than -8dBm, the mixer achieves; a voltage conversion gain up to +16.5dB, an IP/sub -1dB/ of -2dBm, an IIP3 more than +10dBm and up to +55dBm IIP2. When matched to 50/spl Omega/, the mixer operates over an RF range from 0.8 GHz up to 2.2 GHz and drains 3.6 mA from 2.7 V supply. These features make of it a suitable device for multiband receivers using direct conversion architecture.