MAX2235

19-1463; Rev 0; 5/99 ANUAL N KIT M EET IO T A U EVAL TA SH WS DA FOLLO +3.6V, 1W Autoramping Power Amplifier for 900MHz Applications Features o 800MHz to 1000MHz Operation o High Output Power at 836MHz +32.5dBm at +5.0V +30dBm at +3.6V +29dBm at +3.0V +28dBm at +2.7V o +2.7V to +5.5V Single-Supply Operation o Automatic Power-Up/Power-Down Ramp o Direct On/Off Keying (OOK) without Intersymbol Interference or VCO Pulling o 37dB Power-Control Range o 47% Efficiency o <1µA Supply Current in Shutdown Mode o Small 20-Pin TSSOP Package with Heat Slug General 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 noi...