AOC P/N : 41A50-144 service manual Clock Recovery Characteristics, Sampling Phase Adjustment

The table below summarizes the characteristics of the clock recovery circuit.

Table 7. Clock Recovery Characteristics

Patented digital clock synthesis technology makes the gmZAN1 clock circuits very immune to temperature/voltage drift.

2.2.1 Sampling Phase Adjustment

The ADC sampling phase is adjusted by delaying the Hsync input at the programmable delay cell inside the gmZAN1. The delay value can be adjusted in 64 steps, 0.5 ns/step. The accuracy of the sampling phase is checked by the gmZAN1 and the “score” can be read in a register. This feature will enable accurate auto-adjustment of the ADC sampling phase.

2.2.2 Source Timing Generator

The STG module defines a capture window and sends the input data to the data path block. The figure below shows how the window is defined.

For the horizontal direction, it is defined in SCLKs (equivalent to a pixel count). For the vertical direction, it is defined in lines.

All the parameters in the figure that begin with “Source” are programmed into the gmZAN1 registers. Note that the vertical total is solely determined by the input.

The reference point is as follows:

zThe first pixel of a line: the pixel whose SCLK rising edge sees the transition of the HSYNC polarity from low to high.

zThe first line of a frame: the line whose HSYNC rising edge sees the transition of the VSYNC polarity from low to high.

The gmZAN1 also supports the use of analog composite sync and digital sync signals as described in Section 2.3.2

Figure 5. Capture Window