Ahmedalboshra
Junior Member level 1
I am designing a GPS L1 band Direct RF sampling receiver and the front-end goes like this :
(passive antenna + LNA(25dB) + GBA + jumper + BPF(L1) + GBA(23dB) + GBA(23dB) + VGA(-13.5 to +18 Gain Control in 0.5 dB Steps) )
supplied with a +5 V power with decoupling capacitors and a circuit switch after each component to view the signal.
I printed the circuit PCB but when it comes to testing I keep seeing this noise peak through the RF line test points just by turning ON the power supply +5V without any RF input signal ( L1 test signal ).
But when I remove the jumper this noise disappear. I have no idea what's going on and I am thinking there is a feedback noise from the amplification but I still don't know what to do with it.
I have tried different solutions and one of them is adding more decoupling capacitors and still did not work.
if you have any suggestions I would really appreciate it
(passive antenna + LNA(25dB) + GBA + jumper + BPF(L1) + GBA(23dB) + GBA(23dB) + VGA(-13.5 to +18 Gain Control in 0.5 dB Steps) )
supplied with a +5 V power with decoupling capacitors and a circuit switch after each component to view the signal.
I printed the circuit PCB but when it comes to testing I keep seeing this noise peak through the RF line test points just by turning ON the power supply +5V without any RF input signal ( L1 test signal ).
But when I remove the jumper this noise disappear. I have no idea what's going on and I am thinking there is a feedback noise from the amplification but I still don't know what to do with it.
I have tried different solutions and one of them is adding more decoupling capacitors and still did not work.
if you have any suggestions I would really appreciate it