AKD4626A-B Datasheet, PDF (6/44 Pages) Asahi Kasei Microsystems – Multi-channel Audio CODEC.

ASAHI KASEI
„ Consideration for analog output circuit
3.0Vpp
AK4626A
ROUT1 28
LOUT1 27 ^{Same circuit}
22u
10k
ROUT2 26 ^{Same circuit}
LOUT2 25 ^{Same circuit}
ROUT3 24 ^{Same circuit}
LOUT3 23 ^{Same circuit}
NJM4580
+
-
4.7k
4.7k
220
330p
6.0Vpp
Signal
[AKD4626A-B]
1) Frequency response of HPF
The HPF is implemented on board to cancel the DC offset of analog output of AK4626A.
Frequency response of 1st-order HPF
| Amplitude |² = 1/{1+(fc/f)²}; fc=1/2πRC=0.7Hz@R=10k,C=22u
fin
20Hz
Frequency Response -0.006dB
2) Gain, S/N and frequency response of op-amp circuit
1st-order filter with non-inverting amp is implemented on board to double the analog output level and attenuate out-of-band
noise.
a) Gain
The gain is
1+4.7k/4.7k = +6.02dB.
Therefore the output level of this board is
0.51dBV(=3.0Vpp) + 6.02dB
= 6.53dBV = 6.00Vpp = 2.12Vrms.
b) S/N (Theory: BW=20k+A)
The output noise level of non-inverting amp
-110.36dBV = -116.89dB (0dB=6.53dBV)
S/N of DAC is
106.3dB (measurement)
Therefore total S/N of op-amp circuit and DAC is
105.94dB (measurement: 106.1dB).
<KM079800>
-6-
2005/11