transistor mixer circuit

i have so many notes ,and theories:

"use a mixer with in put x(t) and Acos(ft) and out put of x(t)XAcos(ft) is the x(t) signal shifted by f in frequency domain",

any how i want to know what are the practical circuit to implement this mixer(or the multiplier)?


PLEASE !

thanx

Yes, the output spectrum will be shifted by f at frequency domain.
For practical mixer implementation, one way is to use the non-linearity of certain devices as diodes or transistors to generate |n*f1±m*f2| where n, m are integers and f1, f2 are the required drequenciese ti be mixed together.
Another way to perform the mixing function is to use the carrier frequency to drive switches to reverse the polarity of the input signal.
For more information concerning mixer circuits you may refer to "RF microelectronics" by Behzad Razavi, chapter 6.

thanks.
do you have any circuit that i can build.


simple one.

check single transistor mixer , it is qyite simple

khouly

by using a single transistor and biasing two of the ports you can easily make a mixer(which is a king of multiplier).

Please can any one give me a sample schematic of one transistor mixer?

thx

check out this.....

http://www.aaroncake.net/circuits/mixer1.asp

if you want better characteristics try this....

http://www.geocities.com/tomzi.geo/mixer/mixer.htm

I need RF mixer(Multiplyer,actually multiply two wave forms),not a audio mixer

A=x(t)
B=Ecos(2ft)
AXB<----i want this

tanks

dude one of the circuits that i posted (the FET model) have 2 inputs and you just have to feed the two waves that you are talking about....

hope it is helpful....

actually i need a multiplier,not adder
(in Rf terms we called mixer for multiplier)

Added after 1 minutes:

a good name is "modulator"
sorry for my wrong words in earlier posts
thx

if you're trying to build on transistor level, I normally design my mixer with a differential amplifier type.

try this circuit....

See whether this tutorial help you
This is a microwave mixer.
Abhishekabs