plz help,how this circuit work

Many logic ICs can be used as frequency multipliers. One example is shown in the schematic. The LC filter is then used to peak 50 MHz out of other harmonics.

I have used a 74F04 as a frequency multiplier, too; from 26 MHz input I generated 1040 MHz for the use as a receiver LO.

It isn't multiplying the frquency, it works because the fast falling and rising edges of the gates output signal contain a lot of harmonics. The filtering afterwards removes all but the one you need. In this case the fifth harmonic.

Brian.

could you explain it in detail sir
i really cant understand how the 10MHZ signal go into mc10116 and whats output
does L33(10uF)stop the signal and nosignal goes into mc10116'leg12,10,5,11
is output square wave？

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could you explain it in detail sir
i really cant understand how the 10MHZ signal go into mc10116 and whats output
does L33(10uF)stop the signal and nosignal goes into mc10116'leg12,10,5,11
is output square wave？

The MC10116 is a line receiver, it detects small changes between the input pins of each amplifier and uses it to switch the logic state at the output pins.

L33 and C167 are there to make sure the input signal does not reach the other amplifer input but they are kept at the same DC potential. Under these conditions it is most sensitive. The output pins switch very rapidly and produce lots of harmonics, the network after T3 is a 50MHz filter so that only the 5th harmonic (50MHz) passes through. The output from T4 contains the unfiltered signal so it will be rich in harmonics.

I'm not sure that either R84 or R88 are wired properly in the schematic. It would seem more sensible to load the outputs symetrically.

Brian.

The IC is a digital device. It produces Square waves. Sqaure Waves have many Harmonics to change the
Sine wave to a squares wave. (Go read up on Fourier analysis http://en.wikipedia.org/wiki/Fourier_series).
So at the output the have a very narrow/High-Q Band Pass Filter to attenuate all the other Frequencies/Harmonics except for 50MHz.

FYI: I could not see the whole schematic, and did not look at the IC's Data sheet. So my post just
gives the general theory. You will need to investigate. Try changing RF in freq from 10 MHz to 5-20MHz.
Have fun.

THANK YOU FOR YOUR HELP,SIR.so 10MHZ signal input pin13 ,but ,i cant understand what is pin 12&11's input ,if they are dc signal ,where is dc come from,is pin14 a feedback?

Check the data sheet. Pin 11 is reference voltage output which is used to set the bias on all three amplifiers. If you look closely, all three amplifiers have their inputs in parallel, L33 makes sure that all the inputs have the same DC bias conditions on them. C167 ensures that one of th inputs has no signal on it while the inductance of L33 isolates the other input from also being grounded by it. It doesn't matter which input of each amplifier is used for this application, I would guess the reason one amplifier has it's input's swapped is to do with PCB layout.

All three stages have the same output signal, a harmonic rich square wave. The bottom amplifier isn't used, the middle one is unfiltered and the top one feeds a 50MHz filter.

Brian.

To "change the Sine wave to .... "

A very strange concept.

A square wave "changes" nothing.

However, it may be shown that a square wave consists of a sine wave at the frequency of the square wave, plus the sum of odd harmonics up to infinity, the magnitude of each harmonic being inversely proportional to its order.

In other words, the third harmonic has an amplitude of one third that of the sine, the fifth harmonic of one fifth that of the sine etc.

The assumption was that the input is a sine wave, and the output is a square wave.

Yes. So what? A square wave "changes" nothing.

50MHz output is at least sine wave. A resonant tank makes it so at resonant frequency. Frequency selection is also feature of the this filter combination in output.