This paper considers the design of robust logarithmic μ-law companding quantizers for the use in analog-to-digital converters in communication system receivers. Quantizers are designed for signals with the Gaussian distribution, since signals at the receivers of communication systems can be well modeled by this type of distribution. In order to reduce energy consumption, low-resolution quantizers are considered (up to 5 bits per sample). The main advantage of these quantizers is a high robustness - they can provide approximately constant SNR in a wide range of signal power (this is very important since the signal power at receivers can vary in wide range due to the fading and other transmission effects). The logarithmic μ-law companding quantizers eliminate the need of using AGC (automatic gain control), which reduces the implementation complexity and increases the speed of the analog-to-digital converters (ADC) due to the absence of AGC delay. Numerical results show that the proposed model achieves a good performance, better than a uniform quantizer, especially in a wide range of signal power. The proposed low-bit ADCs can be used in MIMO and 5G massive MIMO systems, where due to high operating frequencies and a large number of receiving channels (and consequently a large number of ADCs), the reduction of ADC complexity and energy consumption becomes a significant goal.
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