Hi,
I need to convert the output current (up to 2uA) of a micro-channel plate, MCP, (with 32 anode strips) into a suitable voltage (5V max) for our data acquisition system. The required gain for the transimpedance amplifier is around 2megahoms and the bandwidth 300kHz, in order to see the signal shape (not the single pulses of the MCP, but the whole bunch of particles arriving the detector). For that purpose, I have designed a transimpedance amplifier based on a 50ohms termination resistor and a two stages voltage amplifier (see attached images). In the lab tests, the amplifier doesn't show a brilliant signal/noise ratio but it allows me to do good enough measurements of a test signal. When I connect it to the MCP (through 45 metre of URM-43 50ohm cable, as the detector is within a high ionization radiation area), the amplifier oscillates at about 33kHz. Does anybody know how to stop this oscillation? Is it caused by the cable capacitance? Any ground loop perhaps?
Many thanks
I need to convert the output current (up to 2uA) of a micro-channel plate, MCP, (with 32 anode strips) into a suitable voltage (5V max) for our data acquisition system. The required gain for the transimpedance amplifier is around 2megahoms and the bandwidth 300kHz, in order to see the signal shape (not the single pulses of the MCP, but the whole bunch of particles arriving the detector). For that purpose, I have designed a transimpedance amplifier based on a 50ohms termination resistor and a two stages voltage amplifier (see attached images). In the lab tests, the amplifier doesn't show a brilliant signal/noise ratio but it allows me to do good enough measurements of a test signal. When I connect it to the MCP (through 45 metre of URM-43 50ohm cable, as the detector is within a high ionization radiation area), the amplifier oscillates at about 33kHz. Does anybody know how to stop this oscillation? Is it caused by the cable capacitance? Any ground loop perhaps?
Many thanks
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