I am pretending that laplace does not exist because I am being tested on these concepts separately.
Essentially, I have solved for the step response of a first order circuit and found it to be:
$$v_{c}(t)=\left(\frac{-5}{99}e^{-5t}+\frac{106}{99}e^{\frac{-t}{20}}\right)u(t)$$
I'm only dealing with LTI systems so I know that the impulse is the derivative of the step, but I will be left with some terms attached to the delta function, and some terms attached to the unit step function.
$$h(t)=
\left( \frac{-5}{99}e^{-5t}+\frac{106}{99}e^{\frac{-t}{20}} \right)\delta(t)
+
\left( \frac{25}{99}e^{-5t}+\frac{53}{990}e^{\frac{-t}{20}} \right)u(t)$$
If I want to use the impulse response in the convolution integral, how do I handle these delta terms to make it less… convoluted? Do they reduce to a constant?
Best Answer
You don't have to worry about \$\delta(t)\$ since the integral of it results in \$u(t)\$. Even integrating it alone gives \$\int_0^x{\delta(\pm t)\text{d}t}=2u(x)-1\$. So whatever convolutions you'll have with \$h(t)\$ will include the step function in the result. BTW, the derivative is with \$-\frac{53}{990}\$ in the 2nd term.