Hi TI,
I have a few questions concerning Quad architecture.
I've measured the voltage on the laser diode (specifically cathode of D12) and I've found out, that each quad consists of both frequencies (for dual modulation frequency). Unlike my initial idea, that each quad is measured for only one mod. f. The modulation frequencies were set to f1=40 MHz and f2=80 MHz. The screenshot from the oscilloscope of one quad is depicted on figure 1 - In the upper part you can see the whole quad, the first half has a frequency of 40 MHz, the second half has frequency of 80 MHz and about 20 % lower amplitude. In the lower part there is the focused transition between those frequencies.
Figure 1 - Quad for 40 and 80 MHz
1) Is the amplitude of the higher frequency really significantly lower or is there only a problem in my measurements? (I am using a 500 MHz probe)
2) How different are the quads within one sub-frame? I will specify my question in the next paragraph.
In your User's guide (from May 2014) you are presenting the following model of the pixel (figure 2). Thus my first assumption was, that two phase windows (180° shifted form each other - controlled by signals DMIX0 and DMIX1) are measured within one quad. But with the information, that there are both frequencies in one quad I am not sure anymore.
So are there really two frequencies AND two phase windows measured within one quad?
If so, then how? There would be 4 different information - f1φ, f2φ, f1(φ+180°),f2(φ+180°). I can imagine it with either two additional "capacitors" to store the information OR additional read-out and reset after the f1 is finished.
Figure 2 - Simple model of the pixel
3) Which phase windows are being used for both single and dual modulation frequency?
All my assumptions here are essentially dependent on the answer on the previous question.
But just for Illustration of what I mean:
Lets say that for single mod.f we have 4 quads within one sub-frame and the pixels are working according to figure 2. Is it then correct that in the first quad there are windows of 0° & 180 ° shift from the reference signal, then for second quad 90° & 270 for the third 180° & 360° for the fourth 270° & 90°?
Wouldn't the 3. and 4. quad be redundant when they are actually the same as 1. and 2.?
And which phase windows are used for 6 quads and dual modulation frequency?
Thank you very much for your answer.
Martin
