I am building an 8 bit VGA circuit and have 3 choices. One is to use a simple resistor network to convert digital to analog. The second is to use an op-amp. The third way to do this is to use a device like this CS4344. (This isn't suitable because of the frequency, but I am still looking for a low cost DAC.) I am looking for a cost effective but accurate way to do this. I know the pure resistor solution is probably the cheapest but the issue is it requires a lot of digital pins. However with a serial DAC I can use fewer pins. The data rate will be about 24Mhz at 30fps (it will be 640x480 resolution.) What is a good way to do this?
If I just use resistors in parallel, how do I impedance match for 75 ohm? Is this necessary or is it not needed?