3.16 Filters Flashcards
What is a filter circuit?
A circuit designed to perform frequency selection by selectively filtering one frequency or a range of frequencies from a mix of different frequencies.
What are the three main functions of electronic filters?
- Allow certain electrical frequencies to pass through
- Block certain frequencies from passing through
- Completely block direct current electrical energy
What is a two-port network?
A circuit with an input port and an output port, often analyzed as a ‘black box’ with unknown contents.
What are the four different groups of filters?
- Low-pass Filters (LPF)
- High-pass Filters (HPF)
- Band-pass Filters (BPF)
- Band-stop Filters (BSF)
What is the series connection of a high-pass filter and a low-pass filter called?
Band-pass filter.
What is the parallel connection of a high-pass filter and a low-pass filter called?
Band-stop filter.
What is the principle of operation of low-pass filters?
They let low frequencies pass, including DC voltages, but block frequencies above the upper cut-off level.
What are the two basic kinds of circuits used for low-pass filters?
- Inductive low-pass filter
- Capacitive low-pass filter
How does an inductive low-pass filter work?
The inductor’s impedance increases with increasing frequency, blocking high-frequency signals.
How does a capacitive low-pass filter work?
The capacitor’s impedance decreases with increasing frequency, shorting out high-frequency signals.
What is the principle of operation of high-pass filters?
They let high frequencies pass but block frequencies below the lower cut-off level.
What are the two versions of high-pass filters?
- Inductive high-pass filter
- Capacitive high-pass filter
How does a capacitive high-pass filter work?
The capacitor’s impedance increases with decreasing frequency, blocking low-frequency signals.
How does an inductive high-pass filter work?
The inductor’s impedance decreases with decreasing frequency, shorting out low-frequency signals.
What is a band-pass filter?
A filter that only lets frequencies of a particular band pass, with an upper and a lower cut-off frequency.
What is a common application of band-pass filters?
Used in wireless transmitters and receivers to limit the bandwidth of the output signal.
What is a band-stop filter?
A filter that lets all frequencies pass except for a particular frequency band.
When would a band-stop filter be used?
To remove a specific interfering frequency, such as in radio receivers close to a transmitter.
What is the Q factor in filter circuits?
The ratio of oscillating energy to lost energy in the circuit, influenced by component resistance.
What is bandwidth in the context of filters?
The range of frequencies that are allowed to pass, typically measured between points where amplitude is 70.7% of peak.
True or False: Bandwidth is a sudden cut-off point in frequency response.
False.
What was the original bandwidth channel separation in radio communications?
50 kHz.
What is the current bandwidth channel separation due to technological improvements?
8.33 kHz.
