Saturday, February 1, 2014

Small Signal RF Amp

I have had an idea for an small signal RF Amplifier that I want to try. LTSpice suggest the gain will be good and the linearity appears to be good, or at least that is what the LTSpice FFT plot suggests. This Amp is similar to those that I have used in my Digital 15 Watt Power Amp, but biased for linearity.

My Goal for this circuit is Low Part Count and good Performance. And, as always, a major goal for all of my projects is to make them as Small as my Eyes, Nerves and Methods permits. Yes, I know there are published circuits that may work better, but this is my attempt.

This layout is a single-sided board, with ground plane on the backside. The SMA connectors, connects all ground planes together at the circuit board edge. A layout for a commercial manufactured board would include many via's to assist with ground plane connections.

The first Toner Transfer (TT) version of the circuit had a schematic error (my screw up, I was just to quick on the print button). The second version is shown here.

Etched and
Toner was Removed Underwater with Scotch Bright

Solder Wiped
and Ready for Cut and Part Installation
But alas, I made the power pads too small and they pulled up with only a slight tug on the cable, layout will need to be re-done.

Circuit Complete
with Jury Rigged Power Cable

The PCB is 0.6 x 1.1 inches

The circuit performance tests will have to wait until tomorrow. I will have to devise some interesting tests. Noise Figure, Gain and Large Signal behavior are things I am interested in checking.

On this Rev 02, I forgot to add a Power LED, so I am now working on Rev 03, which will correct all of the known layout problems.


No comments:

Post a Comment