Q:

Is input impedance of an opamp independent from its input's frequency components?

If input impedance of an op-amp is infinite (theoretically), does frequency of an input signal have any effect on input impedance of the op-amp?

A:

If something has an infinite impedance then  any frequency cannot affect it however, it's never going to be infinite and as frequency rises the small amount of capacitance associated with the input will start to become significant even if the input resistance stays in the Giga ohm range.
The frequency won't affect the capacitance but the amplitude of the voltage may cause this capacitance to change slightly on some devices. See varactor diodes and miller capacitance changes with applied voltages.

A:

Theoretically, or more precisely, ideally, the answer is no.  If
$$Z_{in}(\omega) \rightarrow \infty$$
for an ideal op-amp, then there is zero input current for any input voltage of any frequency.
But, this isn't surprising or, for that matter, very interesting.  Ideal op-amps are an abstraction that, in the appropriate context, are a good approximation to physically realizable op-amps.
In other words, for real op-amps, the input impedance is finite (though relatively large) and varies with frequency.

