Final answer:
An OPAMP-based first-order low-pass filter does not act as an integrator across different frequency ranges; it is designed to attenuate signals above the cutoff frequency. Replacing capacitors with inductors in an RLC circuit leads to a high-frequency filter, taking advantage of the inductor's properties. The correct option is: 1. Below the cutoff frequency
Step-by-step explanation:
An OPAMP-based first-order low-pass filter behaves differently across various frequency ranges. Below the cutoff frequency, the filter allows signals to pass with minimal attenuation; however, as you approach the cutoff frequency, the signals begin to be attenuated. Above the cutoff frequency, the filter strongly attenuates high-frequency signals.
When it comes to acting as an integrator, these filters are not designed to specifically perform integration over frequency ranges. Instead, an integrator circuit, which can be built using an OPAMP and a feedback capacitor, will accumulate a voltage over time proportional to the integral of the input signal. This will occur regardless of the specific frequency but is effective only up to the frequency where the phase shift approaches -90 degrees.
If the capacitors are replaced with inductors, an inductor-based filter would operate under different principles. Replacing the capacitor with an inductor in a low-pass filter would not turn it into a high-pass filter. Rather, the inductor's property to impede rapid changes in current would cause the circuit to behave differently and would typically provide high frequency filtering characteristics. An RLC series AC circuit containing inductors can thus act as high-frequency filters.The correct option is 1. Below the cutoff frequency