pixel clock (PCLK)

The pixel clock (PCLK) is a measure of the resolution of displays. It results from the display format and the refresh rate of a display and characterizes the clock frequency for successive pixels. In the case of image sensors, the pixel frequency indicates how often the charge of the pixels can be shifted by one pixel.

For displays, the pixel frequency is calculated from the sum of the lines, the number of pixels per line and the refresh rate. For the pixel clock, the horizontal blanking interval during the line return must be taken into account. For example, for Super- VGA( SVGA) with a resolution of 800 x 600 pixels at a refresh rate of 75 Hz and a blanking interval safety value of 20%, the pixel clock is 800 x 600 x 75 x 1.2, i.e. 43.2 MHz; for Ultra-XGA( UXGA), displayed at 85 Hz, the pixel clock is over 190 MHz. The pixel clock is directly related to the video bandwidth. This corresponds to half the pixel clock.

For CCD sensors, the pixel clock determines the time needed to transport the charge from one pixel to the next. The frequency for the pixel clock is about 50 MHz.