130 nm CMOS Mixer and VCO for 2.4 GHz Low-power Wireless Personal Area Networks

This paper describes a 2.4 GHz passive switch mixer and a 5/2.5 GHz voltage-controlled negative Gm oscillator (VCO) with an inversion-mode MOS varactor. Both circuits are implemented using a 1P8M 0.13 μm process. The switch mixer has an input referred 1 dB compression point of −3.89 dBm and a conversion gain of −0.96 dB when the local oscillator power is +2.5 dBm. The VCO consumes only 1.75 mW, while drawing 1.45 mA from a 1.2 V supply voltage. In order to reduce the passives size, the VCO natural oscillation frequency is 5 GHz. A clocked CMOS divideby-two circuit is used for frequency division and quadrature phase generation. The VCO has a −109 dBc/Hz phase noise at 1 MHz frequency offset and a 2.35-2.5 GHz tuning range (after the frequency division), thus complying with ZigBee requirements. Keywords—Switch Mixers, Varactors, IEEE 802.15.4 (ZigBee), Direct Conversion Receiver, Wireless Sensor Networks.