1. Some ideas about using one 20-bit Serializer to transmit 40-bit data words and about possible channel synchronization GM

2. SER and SLVS TX/RX Characteristics
Max Clock Frequency = 2 GHz
Area = 100um x 56um
Power Dissipation (estimated) < 2.5 mW
SLVS TX/RX
Max Signal Frequency = 3 GHz
Standard SLVS => 0V-400mV
Size = to be checked in the layout
Power Dissipation (estimated) < 10mW

3. 40-bit words & One 20-bit SER (1)
The Serializer provides a Data Strobe output (DS) – i.e. a clock with frequency FDS = F/20 that can be used as read clock of a FIFO containing the data words
FIFO
SER CK
WR_CK
RD_CK DS
SER_OUT
WR_DATA
RD_DATA
PAR_IN

4. 40-bit words & One 20-bit SER (2)
The 40-bit data word can be stored in two 20-bit FIFO
FIFO_L_WR_DATA = DATA[19:0}
FIFO_H_WR_DATA = DATA[39:20]
In Run Mode the SER alternatively selects FIFO_H and FIFO_L as data sources
A flip flop with D = Q_BAR and CK = DS could generate the read enable for the two FIFOs – e.g.: FIFO_L_RD_EN = Q, FIFO_H_RD_EN = Q_BAR
FIFO_H M U X
SER
FIFO_L

5. 40-bit words & One 20-bit SER (3)
Time evolution of Controls and Data

6. Channel Synchronization
A simple and robust option to guarantee channel synchronization on the Deserializer side could be to transmit the 40-bit word COMMA+NW
COMMA = K character from the 16b/20b encoder
NW = Number of 40-bit words (Hamming encoded)
If the input FIFO is empty the transmitted data id COMMA+NW=0
If the input FIFO is not empty the number of words associated to the current event k is read from a NW_FIFO and NW data word are read and transmitted after the HEADER word COMMA+NW(k)

7. Channel Synchronization
Time evolution of Controls and Data