A 18 mW Tx, 22 mW Rx transceiver for 2.45 GHz IEEE 802.15.4 WPAN in 0.18-µm CMOS

This paper demonstrates a highly integrated transceiver for 802.15.4, consuming a dc power of 18 mW and 22.3 mW in the Tx and Rx mode respectively. The g_m boosted LNA shares the dc current with mixer, complex filter uses transistorized biquads, Limiting Amplifier and RSSI chain uses two local loops to save dc power. In the Tx, 2-point direct FSK modulation using normal sized varactors are used in the PLL, which not only obviates the need for auto calibration but also saves dc power due to the absence of DAC. The low IF receiver achieves a sensitivity of -94 dBm, an over load point of -20 dBm adjacent and alternate channel rejections of 40 dB and 55 dB respectively and a linear RSSI range of 89 dB. The transmitter delivers an OQPSK modulated signal of 0 dBm, with an EVM of 7% and the output spectrum meets the mask requirements of 802.15.4, FCC & ETSI. Implemented in 0.18-μm CMOS, loop filter and the crystal resonator for the PLL are the only external components apart from the decoupling capacitors.