AD9135 Datasheet, PDF (41/117 Pages) Analog Devices – Digital-to-Analog Converters

Data Sheet
AD9135/AD9136
L RECEIVE LANES
(EARLIEST ARRIVAL)
K
K
K
R
D
D
DDARQC
C
DDARDD
L RECEIVE LANES
(LATEST ARRIVAL)
K
K
K
K
K
K
K
R
D
D
DDARQC
C
DDARDD
0 CHARACTER ELASTIC BUFFER DELAY OF LATEST ARRIVAL
4 CHARACTER ELASTIC BUFFER DELAY OF EARLIEST ARRIVAL
L ALIGNED
RECEIVE LANES
K
K
K
K
K
K
K
R
D
D
DDARQC
C
K = K28.5 CODE GROUP SYNCHRONIZATION COMMA CHARACTER
A = K28.3 LANE ALIGNMENT SYMBOL
F = K28.7 FRAME ALIGNMENT SYMBOL
R = K28.0 START OF MULTIFRAME
Q = K28.4 START OF LINK CONFIGURATION DATA
C = JESD204B LINK CONFIGURATION PARAMETERS
D = Dx.y DATA SYMBOL
Figure 52. Lane Alignment During ILAS
DDARDD
JESD204B Serial Link Establishment
A brief summary of the high speed serial link establishment
process for Subclass 1 is provided. See Section 5.3.3 of the
JESD204B specifications document for complete details.
Step 1: Code Group Synchronization
Each receiver must locate K (K28.5) characters in its input data
stream. After four consecutive K characters are detected on all
link lanes, the receiver block deasserts the SYNCOUTx± signal
to the transmitter block at the receiver LMFC edge.
The transmitter captures the change in the SYNCOUTx± signal,
and at a future transmitter LMFC rising edge, starts the initial
lane alignment sequence (ILAS).
Step 2: Initial Lane Alignment Sequence
The main purposes of this phase are to align all the lanes of the
link and to verify the parameters of the link.
Before the link is established, write each of the link parameters
to the receiver device to designate how data is sent to the
receiver block.
The ILAS consists of four or more multiframes. The last character
of each multiframe is a multiframe alignment character, /A/.
The first, third, and fourth multiframes are populated with
predetermined data values. Note that Section 8.2 of the
JESD204B specifications document describes the data ramp that
is expected during ILAS. By default, the AD9135/AD9136 do
not require this ramp. Register 0x47E[0] can be set high to
require the data ramp. The deframer uses the final /A/ of each
lane to align the ends of the multiframes within the receiver.
The second multiframe contains an R (K28.0), Q (K28.4), and
then data corresponding to the link parameters. Additional
multiframes can be added to the ILAS if needed by the receiver.
By default, the AD9135/AD9136 use four multiframes in the ILAS
(this can be changed in Register 0x478). If using Subclass 1,
exactly four multiframes must be used.
After the last /A/ character of the last ILAS, multiframe data
begins streaming. The receiver adjusts the position of the /A/
character such that it aligns with the internal LMFC of the
receiver at this point.
Step 3: Data Streaming
In this phase, data is streamed from the transmitter block to the
receiver block.
Optionally, data can be scrambled. Scrambling does not start
until the very first octet following the ILAS.
The receiver block processes and monitors the data it receives
for errors, including
 Bad running disparity (8-bit/10-bit error)
 Not in table (8-bit/10-bit error)
 Unexpected control character
 Bad ILAS
 Interlane skew error (through character replacement)
If any of these errors exist, they are reported back to the
transmitter in one of a few ways (see the JESD204B Error
Monitoring section for details).
 SYNCOUTx± signal assertion: resynchronization
(SYNCOUTx± signal pulled low) is requested at each error
for the last two errors. For the first three errors, an optional
resynchronization request can be asserted when the error
counter reaches a set error threshold.
 For the first three errors, each multiframe with an error in
it causes a small pulse on SYNCOUTx±.
 Errors can optionally trigger an IRQ event, which can be
sent to the transmitter.
Various test modes for verifying the link integrity can be found
in the JESD204B Test Modes section.
Rev. A | Page 41 of 117