AKD4586 Datasheet, PDF (3/46 Pages) Asahi Kasei Microsystems – Evaluation board Rev.B for AK4586

ASAHI KASEI
[AKD4586]
„ Consideration for analog output circuit
3.0Vpp
AK4586
ROUT1 31
LOUT1 30 ^{Same circuit}
22u
10k
ROUT2 29 ^{Same circuit}
LOUT2 28 ^{Same circuit}
ROUT3 27 ^{Same circuit}
LOUT3 26 ^{Same circuit}
NJM5532
+
-
4.7k
4.7k
220
330p
6.0Vpp
Signal
1) Frequency response of HPF
The HPF is implemented on board to cancel the DC offset of analog output of AK4586.
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
outband 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
105.90dB (measurement: 105.8dB).
<KM065102>
3
2005/7