Specifications

Bluegiga Technologies Oy
Page 39 of 64
R1
R2
C1
C2
WT32i
AUDIO_IN_N_LEFT
AUDIO_IN_P_LEFT
Line input P
Line input N
Figure 20: Differential line input example
9.1.5 Output Stage
The output stage digital circuitry converts the signal from 16-bit per sample, linear PCM of variable sampling
frequency to bit stream, which is fed into the analogue output circuitry. The output stage circuit comprises a
DAC with gain setting and class AB output stage amplifier.
The output is available as a differential signal between AUDIO_OUT_N_LEFT and AUDIO_OUT_P_LEFT for
left channel and AUDIO_OUT_N_RIGHT and AUDIO_OUT_P_RIGHT for right channel.
The output stage is capable of driving a speaker directly when its impedance is at least 16Ω.
Figure 21 show an example of differentially connected speaker and Figure 22 show an example of speaker
connected single-ended. Differential (balanced) connection provides perfect common mode rejection ratio with
effectively 3 dB higher amplitude so it is recommended to use differential signaling always when possible.