KSZ9021GN TR Micrel Inc, KSZ9021GN TR Datasheet - Page 17

• Manufacturer Part Number: KSZ9021GN TR
• Description: Specifications: Number of Drivers/Receivers: 8/8 ; Type: Transceiver ; Voltage - Supply: 3.135 V ~ 3.465 V ; Package / Case: 64-VFQFN Exposed Pad ; Packaging: Tape & Reel (TR) ; Protocol: Gigabit Ethernet ; Lead Free Status: Lead Free ; RoHS Stat
• Manufacturer: Micrel Inc

Micrel, Inc.
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.
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
SIGNAL
XTAL
SIGNAL
RX
TX
ANALOG
HYBRID
NEGOTIATION
GENERATION
TRANSMIT
CLOCK
AUTO-
BLOCK
Figure 2. KSZ9021GN 1000Base-T Block Diagram – Single Channel
COMPENSATION
BASELINE
WANDER
PMA STATE
MACHINES
ADC
RX-
CANCELLER
ECHO
CLOCK & PHASE
RECOVERY
+
17
REGISTERS
NEXT Canceller
NEXT Canceller
MII
CHANNELS
CANCELLER
OTHER
FFE
NEXT
DFE
ALIGN UNIT DESCRAMBLER
PAIR SWAP
SYMBOL ENCODER
&
SIDE-STREAM
SCRAMBLER
PCS STATE
MACHINES
MANAGEMENT
SLICER
CONTROL
&
LED DRIVER
MII
DECODER
+
M9999-091010-1.1
KSZ9021GN