HIGHER GAIN AUDIO AMPLIFIER

The LM4877 is unity-gain stable and requires no external

components besides gain-setting resistors, an input coupling

capacitor, and proper supply bypassing in the typical appli-

cation. However, if a closed-loop differential gain of greater

than 10 is required, a feedback capacitor may be needed as

shown in Figure 2 to bandwidth limit the amplifier. This feed-

back capacitor creates a low pass filter that eliminates

possible high frequency oscillations. Care should be taken

when calculating the -3dB frequency in that an incorrect

combination of R

typical combination of feedback resistor and capacitor that

will not produce audio band high frequency rolloff is R

20k

Ω and C

point of approximately 320 kHz. It is not recommended that

the feedback resistor and capacitor be used to implement a

band limiting filter below 100kHZ.

DS101290-24

Figure 2

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