What are the critical issues regarding PCB layout for the DAC?
• For differential clock input circuits, the transformer should be situated close to the DAC so that the PCB tracking is kept as short as possible. (Tracks should be 25 ohm impedance, but 50 ohm is acceptable with short track lengths). • Power supply noise should be kept to an absolute minimum (less that 10mV) to the analog, reference and clock supplies, as any supply variation will produce clock input to analog output delay variations. This will cause phase modulation on the DAC output, which will tend to dominate the output amplitude changes (amplitude modulation) with output frequencies > 1MHz. A very low impedance supply should be used for these blocks, with as much decoupling as possible. • Power supply tracks should be kept as short and wide as possible. Ground and supply tracks should run adjacent to each other as much as possible.
Related Questions
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