Michael

My first post, and greetings to all at his site, I have been stuck on what may be an easy problem, but I haven't thus far found a good solution. I am making a circuit , which most of is controlled by a ATmega32 chip. I realize there is a forum for chips, but this is more concerned with the surrounding circuity. The chip has 8 ports which can be used as ADC with 8 bit resolution. All I want to do is measure the voltage level on two lines. Sounds easy you might say. However I have two problems. One I dont really want to sample at a very high rate which uses up much of the micro resources. And secondly the resolution I would like would be from around 15 - 20 dB to -40 or -50 dB . OK, so what I thought was use two ADC for each line, one with an amplifier at the begining the other with reduction so the two ports would give a better range, each with with a sample and hold circuit leading into the ADC. My problem is the circuit doesn't work to well, and well...any suggestions?