UHF-Satcom.com - GaAsFET Bias board design                                                                                                      (17/02/2012 22:29:41 -0000)

This is a simple bias board design using the ICL7660 dc-dc converter IC, designed to support 2 gaasfets. A suitable power supply was needed for use with the surplus LNA boards that are sold by www.rfmicrowave.it. It’s designed to run from 7 to 24 volts and provide an adjustable negative supply as well as a ‘select on test’ positive supply current.

The component values for the bias board are as follows:

C1 – Electrolytic 10uF 25v
R1 – 150 or 200 ohm (150 ohm)
R2 – 4.7 to 10K (10k)
VR1 – 5 to 20K (10k)
REG - 78l05 (5 volt)
DC-DC - ICL7660 8pin DIL

The diode is for reverse polarity protection, a 1N4001 or similar is fine. 78L05 and ICL7660 are obtainable from Maplin electronics in the UK. The artwork is available here - its 300dpi and will result in a print that is 5.3 cm X 1.8 cm.