This article appeared in Electronic Design and has been published here with permission.
Despite all of the justified attention given to the part of gigahertz spectrum ranging from upper single-digit, lower double-digit, and even higher frequencies, there’s still lots of important activity at the very lowest end of that gigahertz world. And that means that RF components such as power amplifiers are still important.
Qorvo maintains this is highest-gain, 100-W output L-band compact solution available. The two-stage amplifier operates at pulsed RF CW in frequency range of 1.2 to 1.4 GHz, typically providing 50 dBm of saturated output power with 29 dB of large-signal gain. It operates from a 50-V supply and offers 60% power added efficiency (PAE) with a resultant circuit size that’s claimed to be 70% smaller than equivalent two-stage solutions.
The 13-page datasheet contains the necessary graphs and tables, including the four figures that RF designers often use for their “first-pass” assessment (Fig. 2).
The QPA2511 is matched to 50 Ω with integrated bias circuits and a dc-blocking capacitor at its input port. The robust, rectangular, 48-pin surface-mount package measures just 25 × 12.5 × 3.5 mm, thus simplifying system design, board assembly, and testing (don’t worry, most of those 48 pins are devoted to RF and power grounds). Operating temperature range is −40 to +85°C.
The datasheet also shows a basic evaluation board, approximately 75 × 90 mm, using Rogers 4350B PCB material, along with its schematic and bill of materials consisting of the RF PA; an array of bypass capacitors and two bulk-filtering capacitors; test points and jumpers; a ferrite bead; and two SMA connectors. In addition, there’s an image of the board, both populated and bare (Fig. 3). It’s also available on request as the QPA2511EVBPLPR2 evaluation board.