Description
●The MAX2235 low-voltage, silicon RF power amplifier (PA) is designed for use in the 900MHz frequency band. It operates directly from a single +2.7V to +5.5V supply, making it suitable for use with 3-cell NiCd or 1-cell Li-Ion batteries. The device delivers +30dBm (1W) typical output power from a +3.6V supply or +28dBm from a +2.7V supply.
●The MAX2235"s gain is adjustable over a 37dB range. A power-control pin controls gain and bias to maintain optimum efficiency, even at lower output power levels, thus extending the operating life of the battery. At +30dBm output power, efficiency is typically 47%. An additional power-saving feature is a shutdown mode that typically reduces supply current below 1µA.
●A key feature of this PA is its autoramping capability. During turn-on and turn-off periods, the RF envelope is controlled to approximate a raised cosine on the rising and falling edge, thereby minimizing transient noise and spectral splatter. The ramp time is set by selecting the value of an external capacitor.
●The MAX2235 is intended for use in constant envelope applications such as AMPS, two-way paging, or FSK-based communications in the 900MHz ISM band. The device is available in a thermally enhanced 20-pin TSSOP package with a heat slug.
