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DS992F1 21

CS53L30

4.4 Capture-Path Inputs

Fig. 4-4 shows details of the various analog input gain settings, including control register fields.

Figure 4-4. Input Gain Paths

4.4.1 Analog Input Configurations

The CS53L30 implements fully differential analog input stages, as shown in Fig. 4-5. In addition to accepting fully

differential input signals, the inputs can be used in a pseudodifferential configuration to improve common mode noise

rejection with single-ended signals. In this configuration, a low-level reference signal is sensed at the ground point of the

internal mic or external mic jack and used as a pseudodifferential reference for the internal input amplifiers. Sitting between

the preamp and the PGA is an internal antialias filter with a first-order pole at 95 kHz and a first-order pole at 285 kHz.

Figure 4-5. Op-Amp Level Schematic—Analog Inputs

Fig. 4-6 shows the INx interface and the related connections recommended for a fully differential internal mic. These

connections are truncated in Fig. 4-6.

–6 to +12 dB

with 0.5-dB

steps

Bypass, +10,

or +20 dB

0 or +20 dB

and/or

–96 to +12 dB

with 1-dB steps or

– dB (mute)

INx±,

(x=1,2)

Gain Adjust

Digital Gain

Adjust

ADC1xPGA

...

(Note 1)

Bypass, +10,

or +20 dB

INx±,

(x=3,4)

Gain AdjustDigital Gain

Adjust

ADC2xPGA

...

(Note 1)

1. Gains within analog blocks vary with supply voltage, with temperature, and from part to part. The gain values listed for these blocks

are typical values with nominal parts and conditions.

ADC1x_PREAMP

on p. 54

ADC1x_DIG_BOOST on p. 53

ADC1x_VOL on p. 54

ADC2x_PGA_VOL

on p. 56

ADC2x_PREAMP

on p. 56

ADC1x_PGA_VOL

on p. 54

ADC2x_DIG_BOOST on p. 55

ADC2x_VOL on p. 56

–

Preamp+

–

Preamp–

INx–

INx+

100 k

900 k

100 k

Quick-

Ref

700 k 700 k

Weak-VCM