New RF Transceivers Support Pre-802.11n MIMO And Smart-Antenna Radio Systems
Sunnyvale, CA -- Maxim Integrated Products announced the release of two single-chip RF transceivers designed for single-band 802.11a and dual-band 802.11a/g WLAN applications. The MAX2828 covers the world-band frequency spectrum from 4.9 GHz to 5.9GHz, while the MAX2829 covers both 2.4 to 2.5 GHz and 4.9 to 5.9 GHz bands. The ICs feature a MIMO (multiple-input-multiple-output) mode in which the phase angle of the local oscillator is held constant during transmit/receive operation, allowing multiple transceivers to be synchronized to the system reference oscillator. This feature is critical for 802.11n NxN MIMO radio and smart-antenna-based WLAN applications.
The MAX2828/MAX2829 transceivers are manufactured using Maxim's in-house, high-performance SiGe BiCMOS process. Compared to CMOS-only designs, this process results in as much as 4 dB better receiver sensitivity performance in both 11a and 11g 54 Mbps mode. This performance improvement translates to 58% longer range for line-of-sight WLAN applications and 36% longer range for indoor applications.
The transceivers derive their superior receiver sensitivity from a combination of an RF-optimized IC process technology and innovative circuit design. The result is a low receiver noise figure of 3.5 dB, low oscillator phase noise of -99 dBc/Hz at 100 kHz, only 35 ns group-delay variation in the channel filter passband, and high-I/Q quadrature sideband suppression of 40 dBc. A fast, digital AGC and DC-offset cancellation scheme allows antenna diversity selection within a packet header, thereby further improving range. The transceivers are also designed with -10 dBm receiver input IP3 at max gain, and 80 dB filter channel selectivity, resulting in excellent immunity to 802.11a/g OFDM and 802.11b CCK jammers. On the transmitter side, the Tx output is highly linear, delivering -2.5 dBm for 802.11g and -5 dBm for 802.11a at <2% EVM. This allows the external PA to deliver its maximum power without added distortion from the transceiver, directly improving transmitter range.
The MAX2828/MAX2829 transceivers significantly reduce the radio BOM cost and implementation size by integrating all RF transceiver function blocks between the RF switch and baseband processor I/Os. No external SAW filter is required. The transceivers integrate the full transmit path (from baseband IQ input to RF output) and full receive path (from LNA input to baseband IQ output), a low-noise VCO, a fractional-N PLL synthesizer, and baseband/control interface. The transceivers operate from a +2.7 to +3.6 V supply. A 1microamp low-power shutdown mode saves power during the system sleep mode.
The ICs are available in a small 8 x 8 mm, 56-pin, leadless QFN. An evaluation kit is available.
Source: Maxim Integrated Products