Consider the following system:
- The motherboard contains a LCD controller (SSD1963 from Solomon Systech) and other components (application processor, solenoid drivers, power supplies, etc.)
- The display board contains a white LED backlight driver and re-route LCD signals.
- The TFT LCD (AA050MC01 from Mitsubishi) has a digital RGB interface (24-bit of data).
- The pixel clock frequency is set to 30MHz.
- The electrical ground cannot be connected to the chassis ground.
I would like to reduce radiated noise and improve noise immunity at a maximum in order to pass EMC compliance tests and therefore I need your advices. For your information, I did EMC tests on the first prototypes which showed a few peaks near 70MHz and between 100MHz and 200MHz that overlap the pattern by ~5dB. Refer to my other post for an analysis of one of these peaks.
How can I calculate (or estimate) the required source terminator resistance of the RGB interace signals if I don't know the LCD controller output impedance nor the FFC cables characteristic impedances?
Is a source termination sufficient in this case or should I use other termination techniques?
What kind of noise suppression filters should I add and where (on the motherboard only, on both cards, etc.)? Shall I prefer ferrite beads or capacitor type filters?