Questions tagged [band-pass]
Bandpass is an adjective that describes a type of filter or filtering process; it is to be distinguished from passband, which refers to the actual portion of affected spectrum. Hence, one might say "A dual bandpass filter has two passbands." A bandpass signal is a signal containing a band of frequencies not adjacent to zero frequency, such as a signal that comes out of a bandpass filter.
251 questions
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1 answer
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Building a Bandpass Filter for a Class D amplifer
I have built a class D amplifier with the following schematic however I need to replace the low pass LC filter that I have with a bandpass filter with the following requirements my class D supply is ...
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2 votes
2 answers
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How are the shunt coupling capacitors chosen in this double-tuned HF bandpass filter, and how do they affect the resonance and bandwidth?
I am studying a tunable double-tuned band-pass filter used as an HF preselector. A reference implementation is here: http://www.qrp.gr/hf_allband_filter.htm The topology is: Two LC resonators (left ...
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1 vote
3 answers
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Struggling to Tune My Multi Band Band-Pass Filter
I need to build a tunable band-pass filter for the 1–50 MHz range. However, I’m having trouble with the tuning part because the tuning range of the varicaps available on the market is very limited, ...
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1 vote
1 answer
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Combining differential high-pass Sallen-Key filter and differential amplifier into one op-amp stage?
This is a follow up of this question. I'm building a low-noise differential preamp for measuring PSU output noise with an oscilloscope. The design currently has three functional stages: Differential ...
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1 vote
1 answer
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Is it safe to connect virtual ground that created from 2 separate power supplies to GND on MCU?
I am building a cascaded band-pass filter followed by a comparator to convert the transducer signal into a signal readable by the MCU. To achieve a negative supply, I connected two separated power ...
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-1 votes
2 answers
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Ground Loops & Cascaded Sallen-Key Filters
I have designed a circuit composed of third-order Sallen-Key filters. The simple high-pass and low-pass filters are working without any issues. However, the band-pass filters don’t seem to output any ...
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5 votes
3 answers
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Design an RF front-end for the Si4705 integrated circuit
I am designing my first RF reception circuit. It's purpose is to receive European FM band broadcasts which operate at 87.5 - 108 MHz. The center frequency can be rounded to 98 MHz and bandwidth to 20 ...
2 votes
1 answer
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Why is my band pass filter not working as expected?
I made a band pass filter in ltspice using two op amps. It seems the active high pass filter works right, but the low pass filter is not working as expected. The cutoff frequencies I calculated to be ...
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4 answers
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Which one corresponds to the definition of Q factor?
For bandpass filter the Q factor is defined as: at resonance freq f0 of an LC call it X0(where at resonance X0=XL=Xc) the Q = X0 / R. But which circuit above the Q is defined for?
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1 vote
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Chebyshev bandwith filter realisation on microstrip coupled lines
i'm currently writing a diploma, in part of which i have to synthesize Chebyshev filter on microstrip coupled lines, on 6th degree and 9GGhz f0. I did it on on C and L elements using default formulas, ...
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6 votes
3 answers
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Designing a Sallen-Key Band Pass Filter
when studying about Band-Pass Filters, my notes wrote that the design procedure for a circuit (shown below) is that we first choose the centre frequency, ω0, C2, and Ra in the assumed non-inverting ...
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How to design bandpass filter for different input and output impedances
I have a bandpass filter that currently assumes an input and output impedance of 50 ohms. However, I want to design it to assume an input impedance of 100 ohms. My first idea was to use LC components ...
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2 votes
3 answers
220 views
Bandpass filter circuit design: combining active and passive stages
I want to design a bandpass filter circuit 150-20k Hz to filter signals in audio range. I chose the lower cutoff frequency to be 150Hz to remove powerline noise of 50Hz (it was a significant issue in ...
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0 votes
1 answer
58 views
Amplitude variation of RLC Bandpass Circuit
I'm simulating RLC Bandpass Circuit in LTSpice. At resonance, the output voltage should be 5V (=Vin), but why is my output voltage varying with the series resistance? Here in the image, the output ...
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0 votes
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How to improve a 3rd order passive Butterworth band pass filter?
I’ve built a 3rd-order Butterworth band-pass filter prototype centered at 98 MHz to use as the preselector in an FM receiver. The filter performs as expected within the intended range, but it exhibits ...
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