A Digital-to-Analog Converter (DAC) is a device that converts digital data to an analog signal. It takes the binary input bits, weights and adds these together. Electrically SHF DACs do much more because of the on-chip 3R regeneration (re-timing, re-shaping & re-amplification) but logically this is the only operation a DAC does.
To have it less abstract, let’s assume a 3 Bit DAC in symmetric configuration (i.e. with equal amplitudes steps between the output levels) and for the sake of getting an overview, let’s normalize the voltage contributions. The output amplitude can be realized by adding the individual levels (basically it is just like counting binary). The table below shows a typical 3-Bit DAC scheme:
|D2||D1||D0||Norm. Voltage||Output of a DAC|
This scheme holds true for the 3-Bit DAC as above as well as for the 6-Bit DAC. However, for a 6-Bit DAC one has 26=64 instead of the 23=8 output levels shown above. There is no other difference between a 6 and a 3-Bit DAC. The more bits are used, the more levels the output has (with means greater resolution).