KSZ9021GN View Datasheet(PDF) - Micrel
Part Name
Description
Manufacturer
KSZ9021GN Datasheet PDF : 53 Pages
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Micrel, Inc.
KSZ9021GN
Functional Description: 1000Base-T Transceiver
The 1000Base-T transceiver is based-on a mixed-signal / digital signal processing (DSP) architecture, which includes
the analog front-end, digital channel equalizers, trellis encoders/decoders, echo cancellers, cross-talk cancellers,
precision clock recovery scheme, and power efficient line drivers.
The following figure shows a high-level block diagram of a single channel of the 1000Base-T transceiver for one of the
four differential pairs.
XTAL
CLOCK
GENERATION
TX
SIGNAL
TRANSMIT
BLOCK
ANALOG
HYBRID
BASELINE
WANDER
COMPENSATION
RX
SIGNAL
ECHO
CANCELLER
RX-
ADC
+
OTHER
CHANNELS
SIDE-STREAM
SCRAMBLER
&
SYMBOL ENCODER
PCS STATE
MACHINES
NEXT
NECXATNCCaEnLcLeEllRer
NEXT Canceller
PAIR SWAP
&
ALIGN UNIT
LED DRIVER
DESCRAMBLER
+
DECODER
FFE
SLICER
CLOCK & PHASE
RECOVERY
DFE
AUTO-
NEGOTIATION
PMA STATE
MACHINES
MII
REGISTERS
MII
MANAGEMENT
CONTROL
Figure 2. KSZ9021GN 1000Base-T Block Diagram – Single Channel
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.
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.
Analog-to-Digital Converter (ADC)
In 1000Base-T mode, the analog-to-digital converter (ADC) digitizes the incoming signal. ADC performance is essential
to the overall performance of the transceiver.
This circuit is disabled in 10Base-T/100Base-TX mode.
September 2010
17
M9999-091010-1.1
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