The TLV320ADC5140/PCM5140-Q1 device integrates an ultra-low noise front-end PGA with 120 dB dynamic range performance with a low noise, low-distortion, multi-bit delta-sigma (ΔΣ) ADC with a 108 dB dynamic range. The dynamic range enhancer (DRE) is a digitally assisted algorithm to boost the overall channel performance. The DRE monitors the incoming signal amplitude and adjusts the internal PGA gain accordingly and automatically. The DRE achieves a complete channel dynamic range as high as 120 dB. At a system level, the DRE scheme enables far-field, high-fidelity recording of audio signals in very quiet environments, and low-distortion recording in loud environments. This algorithm is implemented with very low latency (a few µs loop time), and all signal chain blocks are designed to minimize any audible artifacts that can occur resulting from dynamic gain modulation.

The block diagram in Figure 5-1 describes the complete signal chain performance with a high-performance analog microphone.

As shown in Figure 5-1, if the system uses the high performance analog microphone with effective dynamic range performance as high as 114 dB, along with a low-cost, 108 dB ADC without DRE, then the overall signal chain dynamic range gets limited to 106.8 dB (114 dB–7.20 dB) due to the 108 dB ADC. However, once the DRE scheme of the TLV320ADC5140 is enabled, an overall signal chain dynamic range of 112.97 dB (114dB–1.03dB) can be achieved in a very economical manner, even after using a low-cost, 108 dB ADC.

Figure 5-1 DRE Block Diagram