How to simulate a comparator circuit?

[holddreams]

comparator sensitivity simulation

How to simulate a comparator circuit?
Which parameters should be measured?
Anyone can give a spice stimulus netlist for example?

 

[snoop835]

comparator input bias current measuring circuit

Hi holdreams,

You should run a transient analysis to test your comparator functionality. This can be done by inputting Pulse signal at the + pin, and a reference DC voltage at the - pin. If + signal is greater than your DC reference voltage, you should get a high out and vice-versa.

Another characterisation is your input offset voltage of your comparator. Run DC sweep to see your offset voltage. For example, if you are using normal Op-amp as a comparator with Vdd=3.3V (single supply). You tie your - pin to say 1.65 DC and sweep + pin from 0V to 3.3V. For ideal case, if your input is at 1.65V then you should get the same value for the output. Unfortunately this is not true, your output should deviate slightly from ideal value. This deviation is your offset voltage.

You might need to simulate for your comparator sensitivity as well. You can read 'CMOS Mixed-Signal' by J. Baker for more details.

All the best.

-snoop835-

 

[tsanlee]

how to simulate comparator

How to simulate a comparator circuit?
Which parameters should be measured?
Anyone can give a spice stimulus netlist for example?

1.speed of comparator
2.application (VDD ) voltage.
3.quiescent currcnt (bias current )
4.Hystersis or Offset voltage

 

[holddreams]

comparator circuits examples

Thanks for your kindly help!

I referred a datasheet of LinCMOS QUADRUPLE DIFFERENTIAL COMPARATORS(TLC354,TI) in order to know which parameters should be measured during simulation.
Here are my questions:

〈1〉"wide range of supply voltages:1.4v～18v"
Does this mean the same circuit structure can work during 1.4V～18v?Or should the W/L be modified during different supply voltages?

〈2〉How to measure Input Impedance?

〈3〉How to mearure Input Bias Current and Input Offset Current?What's the difference of these two current?

〈4〉In testing the "Response ,Rise and Fall times",Some resistors like 5.1Kohms,50ohms and capacitors 1uF,0.1uF are connected to the comparator circuits.
How much should these resistors and capacitors be? Are they chosen randomly?
I have read another datasheet ,it seems that 5.1Kohms is a special value.why?

〈5〉How to measure Common-mode input voltage range?

〈6〉How much Cload should be added in the comparator output?

〈7〉How to measure High-level output current?

Best Regards.

 

[tandy]

Re: comparator circuits examples

Thanks for your kindly help!

I referred a datasheet of LinCMOS QUADRUPLE DIFFERENTIAL COMPARATORS(TLC354,TI) in order to know which parameters should be measured during simulation.
Here are my questions:

〈1〉"wide range of supply voltages:1.4v～18v"
Does this mean the same circuit structure can work during 1.4V～18v?Or should the W/L be modified during different supply voltages?

〈2〉How to measure Input Impedance?

〈3〉How to mearure Input Bias Current and Input Offset Current?What's the difference of these two current?

〈4〉In testing the "Response ,Rise and Fall times",Some resistors like 5.1Kohms,50ohms and capacitors 1uF,0.1uF are connected to the comparator circuits.
How much should these resistors and capacitors be? Are they chosen randomly?
I have read another datasheet ,it seems that 5.1Kohms is a special value.why?

〈5〉How to measure Common-mode input voltage range?

〈6〉How much Cload should be added in the comparator output?

〈7〉How to measure High-level output current?

Best Regards.

1 the input supply voltage range is 1.4-18v, that means the comparator can operated both single supply and dual supplies. for example -9V- 9V is still acceptable.
2 it is the same as the input-impedance measurement of operation amplifier. you can get the method in baker's book.
3 i have no idea about this. you can refer to other experts.
4 these value should be chose according to the impedance of the test equipment. which also reflects the drive capability of the comparator.

5 you can sweep the input common mode voltage until the comparator is not functional.
6. it is still the impedance of your measurement equipment.
7. sorry i have no idea about this.


regards