Monolithic RF transceiver offers sensitivity
Maxim Integrated Products has introduced the MAX2825/MAX2826/MAX2827 family of single-chip RF transceivers designed for 802.11a/g, 54 Mbps and OFDM radio applications. Manufactured using Maxim's second-generation silicon germanium (SiGe) BiCMOS process, these transceivers can improve receiver sensitivity performance by 5 dB in 11 g 54 Mbps mode when compared to existing CMOS-based designs. This results in a 78 percent longer range for line-of-sight WLAN applications and 46 percent longer range for indoor applications. The MAX2825 is designed for single-band 2.4 GHz 802.11g; the MAX2826 is designed for single-band 5 GHz 802.11a and the MAX2827 for dual-band 802.11a/g applications.
The transceivers derive their receiver-sensitivity performance from distinctive IC process technology and innovative circuit design resulting in a low 3.5 dB receiver noise figure, a low -99 dBc/Hz at 100 kHz oscillator phase noise, less than 40 ns group-delay variation in the channel-filter passband, and high 40 dBc I/Q quadrature sideband suppression. To further improve range performance, fast digital AGC and DC offset-cancellation schemes allow antenna diversity selection within a packet header. These devices are designed with -8 dBm receiver input IP3 and 80 dB filter-channel selectivity, making them immune to 802.11a/g OFDM and 802.11b CCK jammers.
On the transmitter side, the TX output is highly linear, delivering as much as -2.5 dBm for 802.11g and -5.5 dBm for 802.11a, with -36 dBc EVM and -60dB ACPR. This allows the external power amp (PA) to deliver its maximum power without added distortion from the transceiver, thus directly improving transmitter range performance. The long-range and interference-immunity characteristics make the transceivers suitable for both client and access-point radio designs for multi-user, Wi-Fi hotspot applications.
To reduce the radio BOM cost and implementation size, the transceivers integrate all RF transceiver functional blocks between the RF switch and baseband processor I/Os. An external SAW filter is not required. These transceivers integrate the full transmit path (from baseband I/Q input to RF output) and full receive path (from LNA input to baseband I/Q output), a low-noise VCO, a fractional-N PLL synthesizer, and a complete baseband/control interface.
The transceivers operate from a +2.7 V to +3.6 V supply. A 10-microamps low-power shutdown mode is provided to save power during the system sleep mode, critical for embedded Wi-Fi PDA and smartphone applications. The transceivers are available in an 8 mm x 8 mm, 56-pin leadless package. Prices start at $8.50 for the MAX2825 (1000-up, FOB USA). An evaluation kit is available to speed designs.
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