I'm designing a circuit that will allow me to do transistor testing (similar to a curve tracer). One part of the circuit is a power supply that will apply different voltages to the collector / emitter.
** I have posted a question regarding the same circuit, however this is a completely different question. **
I need to monitor the current following into the transistor so I'm using high side sensing because:
- I want to detect possible shorts at the power supply (I>250mA)
- I have a few AD8418 current sense amplifiers that fit the job.
The AD8418 has a gain of 20 V/V so I can get the range I'm interested in using a stable 1 Ohm resistor. Some online reading and searching brought to my attention that "high" values such as 1 Ohm are rarely used for current sensing. However, using a much lower values resistor will result in a much lower output voltage which will have to go additional amplification before being sampled by an ADC. I'm afraid that another stage will add noise, offset error and gain error.
Should I go ahead and use a "stable" 1 Ohm resistor or try another, more complex, solution?