I have to design a microwave amplifier in the frequency range of 0-15GHz. To this end, I need to be able to design circuits with HEMT/PHEMT transistors. Is there a comprehensible manual that teaches precisely how to deal with and manipulate such transistors? I prefer online manual, but books are also welcome. I'm not a professional electrical engineer, so, I need practical explanations of how to build circuits with such transistors.
There aren't many complete references for HEMTs or pHEMTs. It may be because they're relatively new and specialized. I think it's because they're just another variation in the FET family.
Most people learn to initially use FETs by studying MOSFETs and then MESFETs. HEMT/pHEMT usage is so similar to MESFETs, most MESFET techniques can be used without changing a thing. This is why most references are focused on a specific difference, and do not cover general HEMT usage.
Here are a few "RF 101" books I would start with... Pozar, Microwave Engineering
Ludwig, RF Circuit Design
If you still want something specific to HEMTs...
Golio, Microwave MESFETs and HEMTs