CX11656 HomePlug 1.0 PHY Data Sheet
3.4
AFE Interface
The CX11656 provides a simple parallel interface to the analog front end (AFE). The
analog data is clocked into or out of the CX11656 on a 10-bit bi-directional parallel data
bus under control of transmit or receive enable signals and sample clock references
provided to the AFE from the CX11656. The CX11656 also provides a parallel byte-wide
automatic gain control interface.
3.4.1
ADC/DAC Interface
The CX11656 outputs a sequential stream of digital time samples of the OFDM
waveforms for transmission. The digital transmit signal is passed on to the A/D
Converter. The ADC digitizes the analog OFDM receive signal for input to the CX11656.
The DAC converts digital samples into analog waveforms.
3.4.1.1
ADC/DAC Timing Diagrams
AFE TX and RX activity is illustrated in Figure 3-19.
AFE clock waveforms are illustrated in Figure 3-20.
AFE transmit and receive timing is illustrated in Figure 3-21 and Figure 3-22,
respectively.
Figure 3-19. AFE TX and RX Activity
DAC_CLK
TX_EN
ADIO[9:0]
ADC_CLK
RX_EN
TX DATA
TX DATA
TX DATA
RX DATA
RX DATA
RX DATA
102069_023
Figure 3-20. AFE Clock Waveforms
tAFE_H
2.0 V
1.5 V
0.8 V
DAC_CLK,
ADC_CLK
tAFE_L
tAFE_R
tAFE_FT
tAFE_PW
102069_024
102069A
Conexant Proprietary and Confidential Information
3-17
CONEXANT [ CONEXANT SYSTEMS, INC ]
