Contents
What is the quantization noise power?
The quantization noise power is the area obtained from integrating the power spectral density function in the range of − f s / 2 to f s / 2 . Now let us examine the oversampling ADC, where the sampling rate is much larger than that of the regular ADC; that is f s > > 2 f max .
How noise is produced during quantization?
Image Noise Models Quantization noise results when a continuous random variable is converted to a discrete one or when a discrete random variable is converted to one with fewer levels. In images, quantization noise often occurs in the acquisition process.
What causes noise in ADC?
Internally, all ADC circuits produce a certain amount of rms noise due to resistor noise and “kT/C” noise. This noise, present even for dc input signals, accounts for the code-transition noise, now generally referred to as input-referred noise.
How do you keep quantization noise minimum?
The process of oversampling to reduce ADC quantization noise is straightforward. An analog signal is digitized at an fs sample rate that is higher than the minimum rate needed to satisfy the Nyquist criterion (twice the input analog signal’s bandwidth) and then lowpass filtered.
Which noise is present in DAC?
The noise from DAC can be considered as DAC intrinsic noise. It is a combination of thermal noise, flicker noise, switch noise, and other noise sources in DAC.
How to reduce quantization noise in a / D converters?
To reduce or eliminate the ill effects of quantization noise in analog-to-digital (A/D) converters ,. DSP practitioners can use two tricks to reduce converter quantization noise. Thoseschemesare called oversampling and dithering .
What is the average power of the quantization noise?
The analysis of A/D signal-to-noise ratio in Chapter 3 showed that the average power of the quantization noise is q2 /12. Due to the limits of sampling theory, in the frequency domain the spectrum is constrained to the frequencies between ± Fs /2. This characteristic is represented in Figure 5-8.
How is oversampling used to reduce quantization noise?
Oversampling reduces the quantization noise power contained within the input signal bandwidth. In digital signal processing applications, a digital low-pass filter at the A/D output could be used to effectively remove the quantization noise which is contained in the unwanted part of the Nyquist bandwidth.
How is RMS noise measured in an A / D converter?
While the ideal A/D only produces code hits in a single bin, an actual A/D will produce additional codes outside the main bin for any dc input value, due to the presence of noise. The number of codes that fall outside the main bin is the key to measuring the converter’s rms noise.