Regulators Optimized for RF Power Amplifiers

( 1 Sep 2009 )

austriamicrosystems’ AS1332-34 family of step down DC-DC regulators is optimized for noise sensitive RF power amplifiers in single cell Li-Ion battery powered applications. The three devices in the family deliver up to 650mA from an input voltage range of 2.7 to 5.5V, making them ideal for single Li-Ion cells. The AS1332 is optimized for low power RF amplifiers where the output power is dynamically scaled by the supply voltage to improve battery lifetime. An external analog reference voltage is applied to the Vcon input, upon which the output voltage follows the reference voltage within a period of 20µs (multiplied by an internal gain of 2.5), varying the output between 1.3 to 3.16V. This fast rise and fall time ensures plenty of operational margin. The output voltage of the AS1333 is fixed at 3.09V whereas the AS1334 is available in 1.2, 1.5, 1.8, 2.5, 3.0 and 3.3V output voltage versions. The family is designed for minimal space requirements in size-restricted battery-powered applications and is ideal for mobile phones and other portable wireless end equipment. The 2MHz fixed switching frequency minimizes PCB footprint by allowing the use of tiny, low profile inductors and capacitors. This constant frequency switching, together with internal noise reduction circuitry, results in an output voltage ripple of less than 2mV peak-to-peak.

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