Amplifier bandwidth determination.

Dear Ankur,

Ankur Chauhan said:

I want to simulate a model design in which I want to distribute a ramp signal through a buffer amplifier. With this, I want to analyze what bandwidth I need in order that my ramp signal should not degrade.

Unfortunately, every amplifier has some bandwidth limitation, and hence your request that your "ramp signal should not degrade" is not realistic....sorry to write this! Without any details about your ramp signal in your post, you need to establish its frequency components and the extent to which it can be bandlimited without degrading it more than your circuit requirements dictate. This will form the specification for your amplifier's large signal bandwidth if the ramp signal will cause your amplifier show any non-linear behavior ( such as slew-rate limiting). If the amplifier behaves in a totally linear fashion (not likely), then a small-signal AC simulation might suffice to assure its bandwidth met your derived bandwidth requirement. More likely, there will some error between your input ramp with slope S and the output of your amplifier as shown in Figure 1 from reference:

https://ocw.mit.edu/resources/res-6-010-electronic-feedback-systems-spring-2013/textbook/MITRES_6-010S13_chap03.pdf

If so, you can run a series of transient simulations were you measure the difference between several input ramps whose slopes are centered about your ramp's desired slope, to measure the resulting error between the input ramp and amplifier output. You might consider plotting the error magnitude as a function of the slope of your input ramp. This might form an alternative to deriving the signal bandwidth your ramp requires and performing a number of transient simulations over frequency to determine the large signal bandwidth of your amplifier.

Do any of these thoughts hlp Ankur?

Shawn

Figure 1

from reference: ocw.mit.edu/.../MITRES_6-010S13_chap03.pdf