Architecture
LatticeECP2/M Family Data Sheet
Lattice Semiconductor
Each Transmit and Receive channel has its independent power supplies. The Output and Input buffers of each
channel also have their own independent power supplies. In addition, there are separate power supplies for PLL,
terminating resistor per quad.
Figure 2-40. Simplified Channel Block Diagram for SERDES and PCS
SERDES (Analog)
PCS (Digital)
RX REFCLK
Recovered Clock
Receiver
Elastic Buffer
Read Clock
Down
Sample
FIFO
Byte Boundary
Detect, 8b/10b
Decoder
CTC
FIFO
Deserializer
1:8/1:10
Polarity
Adjust
Equalizer
16/20 bits
Receive Data
TX REFCLK
FPGA Receive Clock
FPGA Transmit Clock
To FPGA Core
TX PLL
Up
Sample
FIFO
8b/10b
Encoder
Serializer
8:1/10:1
Polarity
Adjust
8/10 bits or
16/20 bits
Transmit Data
Transmit
From Transmit PLL
(In Common Block)
PCS
As shown in Figure 2-40, the PCS receives the parallel digital data from the deserializer receivers and adjusts the
polarity, detects, byte boundary, decodes (8b/10b) and provides Clock Tolerance Compensation (CTC) FIFO for
changing the clock domain from receiver clock to the FPGA Clock.
For the transmit channel, the PCS block receives the parallel data from the FPGA core, encodes it with 8b/10b,
adjusts the polarity and passes the 8/10 bit data to the transmit SERDES channel.
The PCS also provides bypass modes that allow a direct 8-bit or 10-bit interface from the SERDES to the FPGA
logic. The PCS interface to FPGA can also be programmed to run at 1/2 speed for a 16-bit or 20-bit interface to the
FPGA logic.
SCI (SERDES Client Interface) Bus
The SERDES Client Interface (SCI) is a soft IP interface that allow the SERDES/PCS Quad block to be controlled
by registers as opposed to the configuration memory cells. It is a simple register configuration interface.
The ispLEVER design tools from Lattice support all modes of the PCS. Most modes are dedicated to applications
associated with a specific industry standard data protocol. Other more general purpose modes allow users to
define their own operation. With ispLEVER, the user can define the mode for each quad in a design.
Popular standards such as 10Gb Ethernet and x4 PCI-Express and 4x Serial RapidIO can be implemented using
IP (provided by Lattice), a single quad (Four SERDES channels and PCS) and some additional logic from the core.
For further information about SERDES, please see the list of additional technical documentation at the end of this
data sheet.
2-47
LATTICE [ LATTICE SEMICONDUCTOR ]
