Chapter 28, Problem 73PP

A filter is a circuit designed to pass AC signals in some frequency range and to attenuate others. Common filters include low-pass filters, which allow low-frequency signals to pass but attenuate high frequencies; high-pass filters, which do the opposite; and band-pass filters, which pass a range of frequencies while attenuating signals with frequencies outside the band. Filters are widely used in electronics. Applications include tone and equalizer controls in audio equipment; filters to separate nearby frequencies at cell phone towers; and filters to eliminate unwanted electrical noise in biomedical instruments such as electrocardiographs. A simple design for an RC filter is shown in Fig. 28.27.

Figure 28.27 An RC filter (Passage Problems 73–76)

The circuit shown in Fig. 28.27 is

1. a. a low-pass filter.
2. b. a high-pass filter.
3. c. a band-pass filter.
4. d. impossible to tell without knowing the component values.

in series with the output, whereas in this case it is in parallel.