QN8006B/8006LB
1.5dB step) to optimize the SNR and linearity. The gain setting can be controlled automatically by integrated AGC or
manually set through serial interface.
In receive mode, the single ended audio output level is 1V peak to peak and will be AC coupled to external audio driver.
Digital Audio Interface
With digital audio, the interface operates in slave mode and supports MSB-Justified, LSB-Justified, I2S, DSP1, and DSP2.
The four interface lines are MCK, DIN, DOUT, and WS. MCK and WS can be tri-stated to allow for multiplexing.
4.5 Audio Processing
The QN8006 supports both transmit and receive mode audio processing.
In transmit mode, audio AGC, programmable pre-emphasis, and soft clipping are supported. The AGC state machine will
detect the signal level and control the VGA gain to optimize both SNR and THD. A saturation indicator is also integrated
which will be asserted when the input signal is out of the range of AGC. A soft clipping feature provides graceful
performance degradation when the signal level is higher than a pre-determined level.
Stereo signal is generated by the MPX circuit. It combines the left and right channel signals in the following way:
m(t) = L(t) + R(t) + L(t) − R(t) sin(4π ft + 2θ ) +α sin(2π ft +θ ) + d(t)sin(6π ft + 3θ )
[
] [
0
0
0
Here, L(t) and R(t) correspond to the audio signals on left and right channels respectively, f = 19 kHz, θ is the initial phase
of pilot tone and α is the magnitude of pilot tone, and d(t) is RDS signal. In mono mode, only the L+R portion of audio
signal is transmitted. The 19 kHz pilot tone is generated by the MPX circuit which contributes 9% of peak modulation,
and RDS signal will contribute 2.1% of peak modulation.
In receive mode, stereo noise cancellation (SNC), high cut control (HCC) and soft mute (SM) are supported. Stereo noise
suppression is achieved by gradually combining the left and right signals to be a mono signal as the received signal quality
degrades. SNC, HCC and SM are controlled by SNR and multipath channel estimation results.
Pre-emphasis and de-emphasis functions are also integrated with both 75μs and 50μs time constants. The time constant
can be programmed through the serial control interface.
Rev 2.08 (04/10)
Copyright ©2010 by Quintic Corporation
Page 22
Confidential A
Confidential Information contained herein is covered under Non-Disclosure Agreement (NDA).
QUANTUM [ QUANTUM RESEARCH GROUP ]
