Figure 15 shows a method of generating the standard definition YPBPR signals from an RGB source using a pair of LT6550 triple amplifiers. It should be noted that to ensure Y includes a correct sync, correct syncs should be present at all three inputs or else added directly at the Y output (gated 8.5mA current sink or 350Ω switched to –3.3V). This circuit does not deliberately reduce bandwidth on the color component outputs, but most display devices will nonetheless apply a Nyquist filter at the digitizer section of the “optical engine” in the display unit. The circuit is shown as DC-coupled, so ideally black level is near ground for best operation with the low-voltage supplies shown. Adding input coupling capacitors will allow processing source video that has substantial offset.
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.