speakers used in portable systems, whether internal or ex-

ternal, have little ability to reproduce signals below 150Hz.

Applications using speakers with this limited frequency re-

sponse reap little improvement by using high value input and

output capacitors.

As shown in Figure 1, the internal input resistor, R

input capacitors, C1 and C2, produce a -3dB high-pass filter

cutoff frequency that is found using Equation (2).

f

(Hz)

(2)

The value of R

tics tables.

13

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