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circuit - RF Cafe Forums
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pkvije
Post subject: circuit
Unread postPosted: Mon Jul 18, 2005
9:53 am
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Joined: Mon Jul 18, 2005 9:44
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Posts: 1
kindly answer the difference between the following
circuits mixer, AM modulator, multiplier , sampling
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IR
Post subject:
Unread postPosted: Mon Jul
18, 2005 12:51 pm
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Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Hello,
Multuplier is a device or circuit that multiplies the input frequency,
usually is implemented with Schottky diodes. This device or circuit
should reject the fundamental and odd/even harmonics at its output and
pass only the second harmonic.
Mixer is a device or circuit that
converts a frequency to another frequency by means of doing a multiplication
with a local oscillator frequency. The output of the mixer are the sum
and difference of the local oscillator and input frequency. The mixer
should reject the other frequency (would it be the sum or difference),
this is usually done by connecting a BPF (Band-Pass Filter) at the output
of the mixer. Mixer can be used for up-conversion and for down-conversion.
Mixers can be implemented with Schottky dioes and Baluns or with active
devices such as FETs
AM Modulator is a circuit or device that
performs amplitude modulation over an input signal (Usually some kind
of information signal: data, image or voice). The inputs to the AM Modulator
are the information signal and a constanst frequency carrier signal.
The modulation is done by changing the amplitude of a carrier signal
according to the information signal (mixing). The output is a signal
at the carrier frequency with amplitude that follows that shape of the
information signal.
Sampling is the process which is used to
sample any kind of information. According to the nyquist theorem it
should be done at a frequency that is at least twice high than the frequency
of the sampled signal: fs=2*fm
Where:
fs- sampling signal
fm - sampled signal
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Best regards,
- IR
Posted 11/12/2012
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