Along with the programmable channel gain and digital volume, this device also provides programmable channel gain calibration. The gain of each channel can be finely calibrated or adjusted in steps of 0.1 dB for a range of –0.8-dB to 0.7-dB gain error. This adjustment is useful when trying to match the gain across channels resulting from external components and microphone sensitivity. This feature, in combination with the regular digital volume control, allows the gains across all channels to be matched for a wide gain error range with a resolution of 0.1 dB. Table 12 shows the programmable options available for the channel gain calibration.
|P0_R63_D[7:4] : CH1_GCAL[3:0]||CHANNEL GAIN CALIBRATION SETTING FOR INPUT CHANNEL 1|
|0000 = 0d||Input channel 1 gain calibration is set to –0.8 dB|
|0001 = 1d||Input channel 1 gain calibration is set to –0.7 dB|
|1000 = 8d (default)||Input channel 1 gain calibration is set to 0 dB|
|1110 = 14d||Input channel 1 gain calibration is set to 0.6 dB|
|1111 = 15d||Input channel 1 gain calibration is set to 0.7 dB|
Similarly, the channel gain calibration setting for input channel 2 to channel 6 can be configured using the CH2_GCAL (P0_R68) to CH6_GCAL (P0_R88) register bits, respectively.