What is the noise specification of a digital potentiometer?
Noise specs were removed from the digital pot data sheets in 1999. In a study by the Georgia Institute of Technology, performed under the supervision of Professor P.E. Allen, the DS1267, DS1666, DS1667, and DS1669 were measured for noise. The conclusions of this report were the following: • The equivalent input noise voltage is proportional to the resistance. • The test data of input noise voltages are greater than the calculated thermal noise. • This implies that other noise sources including the test system noise, power supply noise, and parasitic noise caused from board and wiring are coupled into the system. • There exists residual noise in the chips of approximately 10nv/sqrt(Hz) exists in the chips.
