A low-power CMOS direct conversion receiver with 3-dB NF and 30-kHz flicker-noise corner for 915-MHz band IEEE 802.15.4 ZigBee standard

A low-power low flicker-noise receiver front-end for 915-MHz-band IEEE 802.15.4 standard in 0.18-/spl mu/m CMOS technology is implemented. A power-constrained simultaneous noise and input matching low-noise amplifier (LNA) can be achieved by using a conventional inductive degeneration cascode amplifier with an extra gate-source capacitor. In combination with the LNA, a passive mixer showing low 1/f noise performance is adopted to convert the RF signal directly to the baseband signal. The measured results show a conversion gain of 30 dB and a noise figure of 3 dB with 1/f noise corner frequency of 30 kHz. Two-tone test measurements indicate -5-dBm input third-order intercept point and +45-dBm input second-order intercept point. The RF receiver front-end dissipates 2 mA from a 1.8-V supply.