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This paper describes a dual signal path (MIMO) low power, high performance direct conversion WiBro/WiMAX 802.16 e radio transceiver optimized for mobile applications and for coexistence with co-located cellular and WLAN/Bluetooth systems. The direct-conversion transceiver is designed to be very flexible in respect of biasing and programmability, both to allow power consumption to be traded adaptively versus performance, and flexibility for any changes in the new transmission standard. Signal loopback and transmit power detection techniques are used in conjunction with the baseband modem processor to calibrate transmitter LO leakage and the transceiver and receiver IQ imbalances. The receiver achieves a noise figure (NF) of less than 2.5 dB over an operational frequency range of 2.3-2.7 GHz, and the gain is tunable from 0 dB to 97 dB in 1 dB steps. The maximum linear transmit power is 2.5 dBm and the transmit gain can be digitally controlled over a 75 dB range. The transceiver is fabricated in a 0.25 mum SiGe BiCMOS process and consumes 65/103 mA from a 2.8 V supply in OFDMA Rx/Tx modes, respectively.
Date of Publication: Aug. 2008