100BASE-TX DIGITAL BLOCKS
KS8910 100/10 Mbps ETHERNET TRANSCEIVER
4-10
Preliminary Spec. ver
1.4
PHYSICAL MEDIUM ATTACHMENT (PMA)
SCRAMBLING
The Scrambler and Descrambler can be bypassed. This is controllable through a register bit.
Scrambler
The scrambler shall encode a plain-text bit stream derived from the TX_code_bit. The bit stream shall be encoded
by addition (modulo 2) of a key stream to produce a cipher-text bit stream. The key stream shall be the periodic
sequence of 2047 bits generated by the recursive linear function X[n] = X[n-11] + X[n-9] (modulo 2). The scrambler
shall generate the specified non-zero key stream whenever the Active Output Interface is required to transmit a
scrambled data stream.
The key steam sequence can be generated by an 11-bit Linear Feedback Shift Register(LFSR) whose input bit is
the exclusive-OR of its 11th and 9th previous bits, and which contains at least one non-zero bit. The functional
diagram for the LFSR is given Figure 4-5 whereas a functional block diagram of the scrambler s in Figure 4-6.
Figure 4-5. Linear Feedback Shift Register (LFSR)
Figure 4-6. Scrambler Function of KS8910
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
Q0
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Q8
Q9
Q10
Q11
Tx_en
Tx_clk
Rst
lfsr_out
cl/st
LFSR
Tx_en
Tx_clk
lfsr_out
TX_bit
cipher-text_out
Summary of Contents for KS8910
Page 1: ...20 8910 0599 USER S MANUAL KS8910 100 10 Mbps Ethernet Transceriver PHY Preliminary ...
Page 4: ...PRELIMINARY SPECIFICATION vi KS8910 100 10 Mbps ETHERNET CONTROLLER ...
Page 21: ...EXTERNAL SIGNALS KS8910 100 10 Mbps ETHERNET TRANSCEIVER 2 8 Preliminary Spec ver 1 4 MEMO ...
Page 89: ...APPLICATION NOTE KS8910 100 10 Mbps ETHERNET TRANSCEIVER 9 2 Preliminary Spec ver 1 4 MEMO ...
Page 91: ...MECHANICAL DATA KS8910 100 10 Mbps ETHERNET TRANSCEIVER 10 2 Preliminary Spec ver 1 4 MEMO ...
Page 99: ...A 8 APPENDIX KS8910 100 10 Mbps ETHERNET TRANSCEIVER Preliminary Spec ver 1 4 NOTES ...