HDMP-1032 Datasheet, PDF (5/32 Pages) Agilent(Hewlett-Packard) – 1.4 GBd Transmitter/Receiver Chip Set with CIMT Encoder/Decoder and Variable Data Rate

HDMP-1032 Tx Block Diagram
The HDMP-1032 transmitter was
designed to accept 16 bit wide
parallel words and transmit them
over a high-speed serial line. The
HDMP-1032 performs the follow-
ing functions:
• Latching parallel word input
• Phase lock to TXCLK
• High speed clock multiplication
• Word encoding
• Parallel to Serial Multiplexing
PLL/Clock Generator
The Phase Lock Loop and Clock
Generator are responsible for
generating all the internal clocks
needed by the transmitter to
perform its functions. These
clocks are based on a supplied
word clock (TXCLK) and control
signals (TXDIV1/0, TCLKENB).
TXCLK is the incoming word
clock. The PLL/Clock Generator
locks on to this incoming
rate and multiplies the word
rate clock by 20 (16 word bits
+ 4 encoding bits). As lock is
achieved, LOCKED is set high.
The TXDIV1/0 pins configure the
transmitter to accept incoming
data words within the desired
frequency range.
By setting TCLKENB high, the
user may provide an external
TTL high speed serial clock at
TXCLK. This clock replaces the
internal VCO clock and is in-
tended for diagnostic purposes
only. This uncharacterized signal
is used directly by the high-speed
serial circuitry to output the se-
rial data at speeds that are not
within the VCO range.
C-Field and W-Field
Encoder Logic
This logic determines what infor-
mation is sent to the encoded
word mux. If TXCNTL is high, the
logic sends bits TX[0-13] and a
C-Field (coding field) encoded
as a control word regardless of
the state of TXDATA. If TXCNTL
is low and TXDATA is high,
the logic sends TX[0-15] and a
C-Field encoded as a data word.
If neither TXCNTL nor TXDATA
is set high, then the transmitter
assumes the link is not being
used. In this case, the logic sub-
mits an Idle Word to the encoded
word mux to maintain the DC
balance on the serial link and
allow the receiver to maintain
frequency and phase lock.
The C-Field logic, based on the
inputs at TXCNTL, TXDATA,
TXFLGENB and TXFLAG, sup-
plies the four bits of the C-field
to the encoded word mux. These
bits contain information regard-
ing the word type: Control, Data
or Idle. In order for the TXFLAG
bit to be used as an additional
data bit, TXFLGENB must be set
high on the Tx and RXFLGENB
must be set high on the Rx. If
scrambling of the encoding of the
flag bit is desired, ESMPXENB pin
must be set high on both the Tx
and Rx. See Flag Descrambler
section on next page for a more
detailed description of the
enhanced simplex mode.
The W-Field logic (word field)
presents either bits TX[0-15]
or an Idle Word to the encoded
word mux.
Encoded Word Mux
The Word Mux accepts the four
encoding bits from the C-Field
and 16 data bits from the
W-Field. These 20 bits of parallel
information are then multiplexed
to a serial line based on the
internal high-speed serial clock.
TXFLAG
TXDATA
TXCNTL
TX[0-15]
FLAG
ENCODER
C-FIELD
ENCODER
SIGN
W-FIELD
ENCODER
Figure 3. HDMP-1032 Transmitter Block Diagram.
5
INVERT
WORD
MUX
PLL / CLOCK
GENERATOR
TXCAP0
TXCAP1
HSOUT ⁺