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What is an oversampling filter?
Oversampling is capable of improving resolution and signal-to-noise ratio, and can be helpful in avoiding aliasing and phase distortion by relaxing anti-aliasing filter performance requirements. A signal is said to be oversampled by a factor of N if it is sampled at N times the Nyquist rate.
What does an anti aliasing filter do?
This filter is an anti-alias filter because by attenuating the higher frequencies (greater than the Nyquist frequency), it prevents the aliasing components from being sampled. Because at this stage (before the sampler and the ADC) you are still in the analog world, the anti-aliasing filter is an analog filter.
Can a decimation filter change the sampling rate?
Further decimation processes can change the oversampling rate back to the desired sampling rate for the output digital signal w ( m ). To examine the SDM, we need to develop a DSP model for the discrete-time analog filter described in Figure 12.29.
How is the high pass filter used in the decimation filter?
In Equation (12.26), the indicated highpass filter pushes quantization noise to the high-frequency range, where later the quantization noise can be removed by the decimation filter. Thus we call this highpass filter (1 − z − 1) the noise shaping filter (illustrated in Figure 12.31 ). FIGURE 12.31. Noise shaping of quantization noise for SDM ADC.
What is the max1402 decimation filter used for?
The MAX1402 can provide 16-bit accuracy at 480 samples per second and 12-bit accuracy at 4,800 samples per second. The chip finds wide application in sensors and instrumentation. The MAX1402 data sheet contains detailed figure information (Maxim Integrated Products, 2007).
How is a decimation filter used in a switched capacitor?
Then the difference is sent to the discrete-time analog integrator, which is implemented by the switched-capacitor technique, for example. The output from the discrete-time analog integrator is converted using an m-bit ADC to produce the oversampled digital signal. Finally, the decimation filter removes outband quantization noise.