IC227 datasheet(3/22 Pages) ICHAUS

3 / 22 page

preliminary

iC227

DUAL 11 GHz SAMPLING OSCILLOSCOPE

Rev B1, Page 3/22

BLOCK DIAGRAM AND THEORY OF OPERATION

iC227 is a simple yet very fast and accurate oscillo-

scope, consisting of a micro-controller and high speed

ECL differential circuitry.

The micro-controller receives commands and re-

sponds via an isolated USB interface running in full

speed mode at 12 Mbit/s.

The sequential scope works by inserting incremental

delays between trigger and sample circuit.

ADC conversion can not start without a trigger event.

Once the trigger has been ﬁred, a high-speed ﬂip ﬂop

is set and the programmable delay lines starts count-

ing time in 10 ps increments.

A ﬁne tuning voltage adjusts ﬁnal time delay with

one picoseconds resolution using DAC calibration data

from micro-controller ﬂash memory.

A Sample is taken on both channels simultaneously

after delay line counting is completed.

It is important to note, that each ADC conversion re-

quires multiple trigger events, limiting the scope usage

to repetitive signals only.

Achieving highly accurate and repeatable time base is

done using proprietary self calibration and ﬁne tuning

techniques.

The device time base is calibrated after assembly and

users have the option to run auto time base calibration.

Time base calibration takes long time, since time base

is scanned with 1 ps intervals and multiple cycles are

repeated, compared to time generated by the crystal

and stored in a ﬂash calibration look up table.

There is no need for frequent time base calibration

since the ECL logic is stable over temperature.

Figure 1: Block Diagram

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