Hi, I've just started getting into electronics and I stumbled across this forum and was very impressed by the knowledge and enthusiasm of the community. I'm excited to learn from you guys!
I was reading a design application on generating sine waves: http://www.national.com/an/AN/AN-263.pdf
On page 8, there's a circuit describing how to approximate a sine using logarithmic shaping. I think I get most of the circuit, but the part I don't understand is the diode section. I can sort of see how it functions as a clamper, but I have no idea why it is "temperature compensated", as they say in the paragraph above.
I'm also confused as to why there appears to be an extra diode in the clamping section (circled). At best, it seems like it will make the clamping section asymmetrical, and at worst it seems to me that when the lm311 swings high, lots of current will flow through that diode to ground. (going right through another diode, then left through the zener, then down through another diode to ground).
Thanks for your help!
Kyle
I was reading a design application on generating sine waves: http://www.national.com/an/AN/AN-263.pdf
On page 8, there's a circuit describing how to approximate a sine using logarithmic shaping. I think I get most of the circuit, but the part I don't understand is the diode section. I can sort of see how it functions as a clamper, but I have no idea why it is "temperature compensated", as they say in the paragraph above.
I'm also confused as to why there appears to be an extra diode in the clamping section (circled). At best, it seems like it will make the clamping section asymmetrical, and at worst it seems to me that when the lm311 swings high, lots of current will flow through that diode to ground. (going right through another diode, then left through the zener, then down through another diode to ground).
Thanks for your help!
Kyle
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