Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would
be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate
that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views.
It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if
you would like to post something on RF Cafe's
page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: circuit
Unread postPosted: Mon Jul 18, 2005 9:53 am
Joined: Mon Jul 18, 2005 9:44 am
kindly answer the difference between the following circuits
mixer, AM modulator, multiplier , sampling
postPosted: Mon Jul 18, 2005 12:51 pm
Joined: Mon Jun 27, 2005
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
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
fs- sampling signal
fm - sampled signal