next up previous
Next: Solution: Maximize the Input Up: Analog to Digital Conversion Previous: Analog to Digital Conversion

Problem: Noise

Because the ADC outputs only tex2html_wrap_inline2066 levels there is inherently noise in the quantized output signal. The ratio of the signal to this quantization noise is called SQNR. The SQNR in dB is approximately equal to 6 times the number of bits of the ADC:


So for a 16 bit ADC this means that the SQNR is approximately equal to 96dB. There are, of course, other sources of noise that corrupts the output of the ADC. These include noise from the sensor, from the signal conditioning circuitry, and from the surrounding digital circuitry

Tim Stilson
Thu Oct 17 11:25:23 PDT 1996