The MAX2242 low-voltage linear power amplifier (PA) is designed for 2.4GHz ISM-band wireless LAN applications. It delivers +22.5dBm of linear output power with an adjacent-channel power ratio (ACPR) of <-33dBc 1st-side lobe and <-55dBc 2nd-side lobe, compliant with the IEEE® 802.11b 11MB/s WLAN standard with at least 3dB margin. The PA is packaged in the tiny 3x4 chip-scale package (UCSP™), measuring only 1.5mm x 2.0mm, ideal for radios built in small PC card and compact flash card form factors.
The MAX2242 PA consists of a three-stage PA, power detector, and power management circuitry. The power detector provides over 20dB of dynamic range with ±0.8dB accuracy at the highest output power level. An accurate automatic level control (ALC) function can be easily implemented using this detector circuit.
The PA also features an external bias control pin. Through the use of an external DAC, the current can be throttled back at lower output power levels while maintaining sufficient ACPR performance. As a result, the highest possible efficiency is maintained at all power levels. The device operates over a single +2.7V to +3.6V power-supply range. An on-chip shutdown feature reduces operating current to 0.5µA, eliminating the need for an external supply switch.
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