Help me understand this clock circuit

Thread Starter

AndrewAK

Joined May 12, 2019
12
Hello every one! i'm new here and i need your help.
Can some one please explain me how this clock circuit works?
My goal is to build circuit that will apply 20MHZ clock to the CLK circuit that on the image.
The main confusion for me is understanding how the circuit work? is it differential clock? and what ic i need to choose in order to accomplish my goal,
my plan right now is connecting evaluation board (DEO-CV) to AD847 that will be configured as buffer and connecting it as mentioned on the picture with ZS and ZO 100 ohm it's going to work?

I don't have any information on the u2 all i know it's deferential amp

thank you :)
 

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MrChips

Joined Oct 2, 2009
23,932
Welcome to AAC!

What you have shown in the circuit diagrams do not generate the 20MHz clocks. They simply condition and relay the signal from another source.
The simple way to source a 20MHz clock is to use a 3 or 4-pin quartz crystal clock module.
 

AnalogKid

Joined Aug 1, 2013
9,290
The circuit is a signal level converter.

The incoming signal is differential. U2C is a differential receiver with a single-ended ECL output. A clue is that R6-R11 form a voltage divider with a 2 V output, which is the termination voltage for ECL. The incoming signals might not be ECL, which would explain the AC coupling and attenuation networks.

What is the U2C part number?

ak
 

Thread Starter

AndrewAK

Joined May 12, 2019
12
The circuit is a signal level converter.

The incoming signal is differential. U2C is a differential receiver with a single-ended ECL output. A clue is that R6-R11 form a voltage divider with a 2 V output, which is the termination voltage for ECL. The incoming signals might not be ECL, which would explain the AC coupling and attenuation networks.

What is the U2C part number?

ak
Hi,
you was right! it's a differential signal(pic-channel 1 is the central pin of coax [notice:there is dc offset] channel 2 is the the coax shield the red channel is the subtraction of this two channels/ the measurement was made by two 100MHZ probes without connecting the ground of the probes ).
the weird part is this signal is applied thru 100ohm impedance coax cable and not twisted wire like differential signal should be, also according the books the clock signal suppose to be 20MHZ square wave 1.6v ~_~ and i got sine in my measurement.
i didn't found any part number or other information about u2 all i know it's differential amplifier.
my goal of this project is to build a circuit that will source the circuit with u2.

guys i need your help!
 

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