CMOS multi-standard wireless direct-conversion receiver for SDR

In this letter CMOS multi-standard wireless direct-conversion receiver is presented. That is composed of wideband LNA, passive double-balanced sub-harmonic mixer, and back-gate coupled quadrature voltage controlled oscillator (QVCO). The frequency operating band of the LNA covers three standards, and it has a differential structure to drive double balanced mixer. The mixer achieved low flicker noise corner and high LO-RF port isolation by using passive sub-harmonic structure. The back-gate coupled QVCO is the structure that uses body connection as another gate. Therefore no coupling transistor is needed, so better phase noise performance is offered.