Hi All...
A strange thing has popped out while SPICE modelling. I hope someone can explain this - I wouldn't normally ask about random SPICE moments, except this weird thing is producing almost exactly the signal I want... but it's popped out in the weirdest place!
I'll try to explain briefly and accurately:
1. I have a comparator which is picking when one signal is higher than another (nothing weird there).
2. This is supposed to then send a logic signal to a couple of inverted CMOS switches to open and close and swap between signals... Cool - I've made that work before...
3. NOW - when I add a resistor in between a buffer and the Comp's input, and read a voltage from between this resistor and the input, I see that the signals are combining at the INPUT side... in a really interesting way too...
4. If I increase one resistor, it changes the amount and way that the signals combine at the input side too. In fact - it's almost doing the exact switching I was after, but a lot smoother than I expected my actual design to do it - and I can't help but want to use this signal now haha...
Can someone please explain if this is unusual or a typical outcome - i.e. what's going on here?!... It's naturally only there when I pop the resistor(s) in there at the inputs (as otherwise the buffers smash out whatever the comparators need which overrides this subtle combining of signals feeding back from the comparator.
If interested, please have a look at the attachment...
The two comparator inputs PRE resistors (out of buffers) are in Red and Blue.
The green line is in between the resistor and the comparator input.
When you look at the green line carefully, you notice that it has a non linear relationship with the others until it ultimately matches back into the blue line... It's basically a super smooth combination of the two, with very little phase delay. Notice also that at high peaks where red is above blue, the green line tracks relatively close, but then further along between 410.4s to 411s it's tracking quite far off, before sliding back into to match the blue line once the signals are no longer close enough to interact...
This is basically the exact control signal I'm after in this new design; it's just at the wrong end of the circuit haha...!
Please let me know if you understand this!
A strange thing has popped out while SPICE modelling. I hope someone can explain this - I wouldn't normally ask about random SPICE moments, except this weird thing is producing almost exactly the signal I want... but it's popped out in the weirdest place!
I'll try to explain briefly and accurately:
1. I have a comparator which is picking when one signal is higher than another (nothing weird there).
2. This is supposed to then send a logic signal to a couple of inverted CMOS switches to open and close and swap between signals... Cool - I've made that work before...
3. NOW - when I add a resistor in between a buffer and the Comp's input, and read a voltage from between this resistor and the input, I see that the signals are combining at the INPUT side... in a really interesting way too...
4. If I increase one resistor, it changes the amount and way that the signals combine at the input side too. In fact - it's almost doing the exact switching I was after, but a lot smoother than I expected my actual design to do it - and I can't help but want to use this signal now haha...
Can someone please explain if this is unusual or a typical outcome - i.e. what's going on here?!... It's naturally only there when I pop the resistor(s) in there at the inputs (as otherwise the buffers smash out whatever the comparators need which overrides this subtle combining of signals feeding back from the comparator.
If interested, please have a look at the attachment...
The two comparator inputs PRE resistors (out of buffers) are in Red and Blue.
The green line is in between the resistor and the comparator input.
When you look at the green line carefully, you notice that it has a non linear relationship with the others until it ultimately matches back into the blue line... It's basically a super smooth combination of the two, with very little phase delay. Notice also that at high peaks where red is above blue, the green line tracks relatively close, but then further along between 410.4s to 411s it's tracking quite far off, before sliding back into to match the blue line once the signals are no longer close enough to interact...
This is basically the exact control signal I'm after in this new design; it's just at the wrong end of the circuit haha...!
Please let me know if you understand this!