How to increase the speed of comparator

[kevinwang123]

if i don't increase the tail current,how to improve the speed of comparator?

 

[feier0251]

decrease the output capacitor

 

[holddreams]

decrease the output capacitor

Then how can we do if the output capacitance is stable?

 

[sisc1525]

you can get a new type for reducing the cap

 

[leomecma]

Sometimes you can put a capacitor frequency compesation capacitor (between input and output) to acelerate the response. Positive feedback increase it too.

leomecma

 

[sunking]

reduce the size (such as L) of the comparator.
and most you can use the latched comparator

 

[huojinsi]

leomecma's post is a good idea. Introduce a positive feedback!

 

[kevinwang123]

thanks all of you!
I use the positive feedback comparator,but the problem can't be solved.

 

[leomecma]

I think you have to choose a new serie of comparator more fast, what speed do you need? Maybe anyone can suggest one ....

leomecma

 

[kevinwang123]

thanks a lot
input range : 0 to 1.2v
frequency: 40MHz
a voltage comparator

 

[leomecma]

Use TLV3501/3502 from Texas Instruments, this works in 80 MHz troggle frequency. For more fast try use ADCMP565 from Analog Devices, it's a 5GHz comparator.

leomecma

 

[muralikrishnap]

I think the speed can be increased by reducing the output resistance of the circuit.
This inturn leads to reduction in gain which can again be increased by increasing the transconductance by choosing appropriate way . ie either by increasing the aspect ratio ( frequency of operation may be affected but good current matching possible) or by increasing the overdrive voltage.

If someone feels I am wrong,, i request the to reply and correct my mistake.

thanks,
Muralikrishna
KPIT Cummins Infosystems Ltd, INDIA