Datasheet

 2016-2017 Microchip Technology Inc. DS00002117F-page 15
KSZ9031RNX
FIGURE 3-2: KSZ9031RNX 1000BASE-T BLOCK DIAGRAM - SINGLE CHANNEL
3.2.1 ANALOG ECHO-CANCELLATION CIRCUIT
In 1000BASE-T mode, the analog echo-cancellation circuit helps to reduce the near-end echo. This analog hybrid circuit
relieves the burden of the ADC and the adaptive equalizer.
This circuit is disabled in 10BASE-T/100BASE-TX mode.
3.2.2 AUTOMATIC GAIN CONTROL (AGC)
In 1000BASE-T mode, the automatic gain control (AGC) circuit provides initial gain adjustment to boost up the signal
level. This pre-conditioning circuit is used to improve the signal-to-noise ratio of the receive signal.
3.2.3 ANALOG-TO-DIGITAL CONVERTER (ADC)
In 1000BASE-T mode, the analog-to-digital converter (ADC) digitizes the incoming signal. ADC performance is essen-
tial to the overall performance of the transceiver.
This circuit is disabled in 10BASE-T/100BASE-TX mode.
3.2.4 TIMING RECOVERY CIRCUIT
In 1000BASE-T mode, the mixed-signal clock recovery circuit together with the digital phase-locked loop is used to
recover and track the incoming timing information from the received data. The digital phase-locked loop has very low
long-term jitter to maximize the signal-to-noise ratio of the receive signal.
The 1000BASE-T slave PHY must transmit the exact receive clock frequency recovered from the received data back to
the 1000BASE-T master PHY. Otherwise, the master and slave will not be synchronized after long transmission. This
also helps to facilitate echo cancellation and NEXT removal.
3.2.5 ADAPTIVE EQUALIZER
In 1000BASE-T mode, the adaptive equalizer provides the following functions:
• Detection for partial response signaling
• Removal of NEXT and ECHO noise
• Channel equalization
Signal quality is degraded by residual echo that is not removed by the analog hybrid because of impedance mismatch.
The KSZ9031RNX uses a digital echo canceler to further reduce echo components on the receive signal.
In 1000BASE-T mode, data transmission and reception occurs simultaneously on all four pairs of wires (four channels).
This results in high-frequency cross-talk coming from adjacent wires. The KSZ9031RNX uses three NEXT cancelers on
each receive channel to minimize the cross-talk induced by the other three channels.
CLOCK
GENERATION
BASELINE
WANDER
COMPENSATION
ECHO
CANCELLER
TRANSMIT
BLOCK
NEXT Canceller
NEXT Canceller
NEXT
CANCELLER
RX-
ADC
AGC
+
FFE SLICER
CLOCK AND PHASE
RECOVERY
AUTO -
NEGOTIATION
PMA STATE
MACHINES
MII
REGISTERS
MII
MANAGEMENT
CONTROL
DFE
ANALOG
HYBRID
PCS STATE
MACHINES
PAIR SWAP
AND
ALIGN UNIT
DESCRAMBLER
+
DECODER
SIDE-STREAM
SCRAMBLER
AND
SYMBOL ENCODER
LED DRIVER
XTAL
OTHER
CHANNELS
TX
SIGNAL
RX
SIGNAL