UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - 0.1-2000 MHz Wide Band Amplifier ~£4

G6Tanuki · 20th Oct 2018, 8:46 pm

MMICs can be useful but they really need to have both their input and output terminated over their full design-bandwidth into a consistent impedance [usually 50 or 75 Ohms] or they can become unstable and sometimes oscillate.

(Remember that every amplifier ever buit has an aspiration to become an oscillator, by fair means or foul!)

Usual trick is to put a 3dB Pi-section resistive 'pad' on the output, using SMD resistors to minimise lead-inductance.

20th Oct 2018, 8:46 pm	#3
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: 0.1-2000 MHz Wide Band Amplifier ~£4 MMICs can be useful but they really need to have both their input and output terminated over their full design-bandwidth into a consistent impedance [usually 50 or 75 Ohms] or they can become unstable and sometimes oscillate. (Remember that every amplifier ever buit has an aspiration to become an oscillator, by fair means or foul!) Usual trick is to put a 3dB Pi-section resistive 'pad' on the output, using SMD resistors to minimise lead-inductance.