Datasheet

1 +

= 18 dB = 7.9

LMV793

LMV793, LMV794

www.ti.com

SNOSAX6D –MARCH 2007–REVISED MARCH 2013

Figure 52. LMV796 Response Gain = +2

The response shown in Figure 51 is close to the response shown in Figure 49. The part is actually slightly faster

in the non-inverting configuration. Decreasing the value of R

to around 200Ω can decrease the negative

overshoot but will have slightly longer rise and fall times. The other option is to add a small resistor in series with

the input signal. Figure 52 shows the performance of the LMV796 with no compensation. Again the

decompensated parts are almost 2.5 times faster than the fully compensated op amp.

The most difficult op amp configuration to stabilize is the gain of +1. With proper compensation the

LMV793/LMV794 can be used in this configuration and still maintain higher speeds than the fully compensated

parts. Figure 53 shows the gain = 1, or the buffer configuration, for these parts.

Figure 53. LMV793 with Lead-Lag Compensation for Non-Inverting Configuration

Figure 53 is the result of using Equation 8 and additional experimentation in the lab. R

is not part of Equation 8,

but it is necessary to introduce another pole at the input stage for good performance at gain = +1. Equation 8 is

shown below with R

= ∞.

(11)

Using 2 kΩ for R

and solving for R

gives R

= 2000/6.9 = 290Ω. The closest standard value for R

is 300Ω.

After some fine tuning in the lab R

= 330Ω and R

= 1.5 kΩ were choosen as the optimum values. R

together

with the input capacitance at the non-inverting pin inserts another pole into the compensation for the

LMV793/LMV794. Adding this pole and slightly reducing the compensation for 1/F (using a slightly higher resistor

value for R

) gives the optimum response for a gain of +1. Figure 54 is the response of the circuit shown in

Figure 53. Figure 55 shows the response of the LMV796 in the buffer configuration with no compensation and R

= R

= 0.

Product Folder Links: LMV793 LMV794