Power Amp Touts Auto-Ramping Output

Said to offer the industry's first power amplifier with an auto-ramping capability, MAX2235 900-MHz, 1W silicon power amplifier is well-suited for use in AMPS, two-way pagers, and FSK-based systems in the 868/900 MHz ISM band. Its RF output is controlled during turn-on and turn-off by an external capacitor to gradually ramp up and down, minimizing unwanted output transient noise and spectral splatter found in pulsed TDMA systems. The power amp is said to offer the highest functionality when compared with existing GaAs MESFET or HBT solutions. Output power is 30.3 dBm at 3.6V with a power-added efficiency of 47%. A power control pin lets the gain be adjusted over a 37 dB range while the bias is automatically changed to maintain optimum efficiency, even at lower output power levels. A shutdown mode reduces the supply current to less than 10 µA with a supply switch. Operation is from a 2.7V to 5.5V supply, eliminating the negative bias and sequencing circuits required for GaAs MESFETs.