A 1.5 V 900 MHz downconversion mixer

The demand for fewer batteries and lighter weight in portable RF transceivers has motivated efforts to reduce the supply voltage of both analog and digital building blocks of such systems. In front-end RF circuits, however, trade-offs among six parameters have constantly challenged the designers: noise, power dissipation, linearity, voltage headroom, gain, and operating frequency. While upconversion mixers with supplies as low as 2 V have been reported, noise, speed, and supply rejection issues prohibit the use of such topologies for downconversion. This 900 MHz downconversion mixer employs circuit techniques to relax some of the above trade-offs. The fully-differential circuit consists of a core and an output buffer/amplifier, and operates from a 1.5 V supply.