HWD2190 Datasheet, PDF (20/32 Pages) List of Unclassifed Manufacturers – 1 Watt Audio Power Amplifier

Application Information (Continued)
As stated in the External Components section, R_IN in con-
junction with C_IN create a highpass filter.
C_IN ≥ 1/(2π*20 kΩ*20Hz) = 0.397µF; use 0.39µF
With a A_VD = 3 and f_H = 100kHz, the resulting GBWP =
300kHz which is much smaller than the HWD2190 GBWP of
2.5MHz. This calculation shows that if a designer has a need
to design an amplifier with a higher differential gain, the
HWD2190 can still be used without running into bandwidth
limitations.
The high frequency pole is determined by the product of the
desired frequency pole, f_H, and the differential gain, A_VD.
HIGHER GAIN AUDIO AMPLIFIER
FIGURE 2.
The HWD2190 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 (C4) may be
needed as shown in Figure 2 to bandwidth limit the amplifier.
This feedback capacitor creates a low pass filter that elimi-
nates possible high frequency oscillations. Care should be
taken when calculating the -3dB frequency in that an incor-
rect combination of R₃ and C₄ will cause rolloff before
20kHz. A typical combination of feedback resistor and ca-
pacitor that will not produce audio band high frequency rolloff
is R₃ = 20kΩ and C₄ = 25pf. These components result in a
-3dB point of approximately 320 kHz.