A2327
AUDIO AMPLIFIER
AiT Semiconductor Inc.
www.ait-ic.com
2.6W MONO FILTER-FREE CLASS-D
Component Recommended
Due to the weak noise immunity of the single-ended input application, the differential input application should
be used whenever possible. The typical component values are listed in the table:
RI
CI
CS
150k
3.3nF
2uF
(1) CI should have a tolerance of ±10% or better to reduce impedance mismatch.
(2) Use 1% tolerance resistors or better to keep the performance optimized, and place the RI close to the
device to limit noise injection on the high-impedance nodes.
Input Resistors (RI) & Capacitors (CI)
The input resistors (RI) set the total voltage gain of the amplifier according to Eq1
2 x 150kΩ V
Gain =
Eq1
RI
V
The input resistor matching directly affects the CMRR, PSRR, and the second harmonic distortion
cancellation.
If a differential signal source is used, and the signal is biased from 0.5V ~ VDD-0.8V (shown in Figure3), the
input capacitor (CI) is not required.
If the input signal is not biased within the recommended common-mode input range in differential input
application (shown in Figure4), or in a single-ended input application (shown in Figure5), the input coupling
capacitors are required.
If the input coupling capacitors are used, the RI and CI form a high-pass filter (HPF). The corner frequency (fC)
of the HPF can be calculated by Eq2
1
Hz
fC =
Eq2
2 x RI x CI
Decoupling Capacitor (CS)
A good low equivalent-series-resistance (ESR) ceramic capacitor (CS), used as power supply decoupling
capacitor (CS), is required for high power supply rejection (PSRR), high efficiency and low total harmonic
distortion (THD). CS is 2μF, placed as close as possible to the device VDD pin.
REV2.1 - NOV 2008 RELEASED, SEP 2016 UPDATED -
- 8 -
AITSEMI [ AiT Semiconductor ]
