YDA131

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Description of operation functions

Refer to "Connection circuit example" on page 11, when reading the following descriptions.

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Gain setting

This IC consists of the first stage inversion operational amplifier, and the fixed-gain digital power amplifier.

The gain of the digital power amplifier is fixed at 8 dB.

driving capability of the operational amplifier is limited.

operational amplifier is set at 16 dB, as described in "Figure 1: First stage inversion operational amplifier input circuit

example". Therefore, the total gain at this case is given as described below.

8dB (fixed gain of the digital power amplifier) + 16dB (gain of the first stage inversion operational amplifier) = 24dB

in "Figure 1: First stage inversion operational amplifier input circuit example", whereby the value can be adjusted as

constitute a high pass filter.

The cut off frequency fc of this high pass filter is set as necessary, and can be decided by "Formula 2".

When low band boost function is needed due to a reason such as small diameter speaker, the low boost function can be

realized by making the circuit of the first stage operational amplifier as shown in "Figure 2: Low band boost circuit

example". For this circuit, the gain is increased by +3dB at the frequency fb of "Formula 3", and the low band boost

quantity Ab is decided by "Formula 4". At this time, the frequency characteristic is as shown in "Figure 3: Frequency

characteristic at low band boost".