1 Introduction

TLV320ADC5140, TLV320ADC6140, PCM5140-Q1, and PCM6140-Q1 devices from TI’s Audio ADC portfolio features an algorithm called Dynamic Range Enhancer (DRE) that can be used to improve the far-field recording performance by improving the dynamic range of the ADC channel at low signal levels. The DRE is a digitally-assisted algorithm that dynamically adjusts the front-end programmable gain amplifier (PGA) to improve the signal-to-noise ratio of low-level signals while preventing high-level signals from saturating the PGA and ADC. Far-field recording performance can also be improved by using a high PGA gain, but it can degrade near-field recording performance since a dynamic change to high-input levels combined with a high fixed-gain PGA can saturate the PGA and ADC. The DRE provides the ability to improve the far-field recording performance without degrading the near-field recording performance. Figure 1-1 shows the improvements in channel performance with DRE. With DRE, the ADC channel performance is not limited by the ADC noise floor and improves the recording performance even for signals below the noise floor of the ADC. Every 6 dB improvement in dynamic range increases the far-field recording distance by a factor of two.

DRE is supported on all ADC channels of TLV320ADC5140, TLV320ADC6140, PCM5140-Q1, and PCM6140-Q1 devices. This application note describes the operation of the DRE, the tunable parameters, and the device configurations required to use DRE.