Hello
Good Afternoon,
My name is Ali I work at Quantum Dimension as a RF design engineer. We at Quantum Dimension are doing research and design for SPAWAR, we are designing a highly efficient and linear Class E RF power amplifier for a Handset application for JTRS and the MUOS program.
In order to get more efficiency we need to have a Drain voltage on the power amplifier that follows the Envelope of the input WCDMA signal. I can achieve this by using two back to back NPN transistors to scale the Envelope signal and then use a N MOS source follower ckt to handle the load current. This would turn out to be highly inefficient.
A better option is to have a Switching Boost regulator do the same thing but with much higher efficiency. unfortunately I was not able to make it work. I have no experience in
power supply design and would really like your help and support on this.
The requirement is to have a input range of 10V thru 18Vdc, with a nominal 12Vdc input and a Voltage output which can move from 12V thru 28Vdc (following the changes in the envelope), so that the highest value on the envelope corresponds to 28Vdc and the lowest voltage goes to 9Vdc. The current rating is min 2A.
Some other researchers have used a Class S or Class D amplifiers or Audio amplifiers to attain the above requirement but again this is limited to research papers and no reference design exists. I am not sure how an Audio amplifier can modulate the Drain voltage to vary with the incoming envelope.
MUOS (Mobile user objective system) is a well funded program and will be taking over JTRS in the future, so any design that we make work will be part of their system in the future.
Thanks and best regards
Ali
RF Design Engineer
Quantum Dimension