From the microphone Sensitivity of -30dBV and AOP of 110dBSPL, the largest input level the microphone can record is -14dBV which is equivalent to 199 mVrms single-ended. A 1KHz tone with 199mVrms is applied to the analog differential inputs of the device under test (DUT) with 0dB gain setting and the digital output is captured with Audio Precision APx555. The following are the results taken on these two devices.

Figure 3-15 Test Case 2: Microphone Maximum Input Level

Figure 3-16 ADC6120 Captured of Maximum mic Input With DRE Disable

Figure 3-17 ADC6120 Captured of Maximum Mic Input With DRE Enable

Here, the digital output level of the microphone maximum level is -20dBFS for differential configuration from the converter's full-scale. Based on the un-weighted Dynamic Range (DR) of the converter, the THDN is calculated by Equation 1 and summarized in Table 3-6 for these devices.