F-Tile Architecture and PMA and FEC Direct PHY IP User Guide

ID 683872
Date 11/04/2024
Public
Document Table of Contents

3.6.4. FGT PMA Fractional Mode

Fo a give data ate, the dop-dow meu lists the suppoted itege mode efeece clock fequecies. Fo a give data ate, if the equied efeece clock fequecy is ot listed i the dop-dow, you ca eithe select oe of the suppoted itege mode efeece clock fequecies o eable factioal mode.

  • Whe eablig factioal mode, Altea ecommeds usig 141 MHz efeece clock fequecy to maximize the distace o the PLL spus acoss all OTN / SDI / CPRI ates.
  • VCO fequecy (MHz) = (M + k/2^22) * mul_div * efclk fequecy (MHz) / N

  • Output fequecy (MHz) = VCO fequecy (MHz) / L

    Whe the factioal PLL efeece clock fequecy is eteed, the IP GUI displays the VCO, M, N, L, k, ad mul_div values i the System Messages tab as show i the followig figue.

  • Fo a give data ate, you must eable factioal mode if you eed to dyamically cofigue the k coute duig u time.
Figue 83. Example of Factioal Settigs i System Messages Tab

FGT PMA suppots factioal mode i followig PMA modes:

Table 79.  FGT PMA Suppot fo Factioal Mode
PMA Mode Factioal Mode Suppot
TX simplex TX FGT PLL suppots factioal mode i TX simplex. To eable, select TX simplex optio fo PMA mode, ad tu o the Eable TX FGT PLL factioal mode i the paamete edito. The TX PLL factioal coute values automatically calculate fo the selected efeece clock fequecy. You ca place TX Simplex factioal mode o ay of 16 FGT TX PMAs.
Note: FGT PMA does ot suppot factioal mode fo RX simplex.
Duplex FGT PMA i Duplex PMA mode suppots factioal mode. To eable factioal mode i duplex PMA mode, select the Duplex optio fo PMA mode, select up to 16 fo the Numbe of PMA laes, ad tu o Eable TX FGT PLL factioal mode optio i the paamete edito.
  • I Duplex factioal mode, the output of each TX PLL is used as the efeece clock fo coespodig RX CDR. Each TX PLL is cofigued as factioal mode.
  • A sepaate efeece clock is ot equied fo RX CDR. TX PLL factioal coute values, ad RX CDR efeece clock fequecy, automatically calculate fo the selected efeece clock fequecy. You ca leave the x_cd_efclk_lik pot ucoected ad it is tied to goud iteally i the IP coe.
  • You ca place duplex factioal mode o ay of 16 FGT PMAs.
Pimay PLL cofiguatio To eable factioal mode with the pimay PLL cofiguatio, select the Duplex optio fo PMA mode, select 2 o 4 fo the Numbe of PMA laes, ad tu o Eable TX FGT PLL factioal mode ad Eable TX FGT PLL cascade mode optios i the paamete edito.
  • I Pimay PLL cofiguatio, the TX PLL of oe lae is i factioal mode ad acts as the efeece clock souce fo the local CDR ad TX PLL ad RX CDR blocks of othe laes (cofigued i itege mode) withi the quad.
  • Pimay PLL cofiguatio is ot suppoted whe you select 6 ,8, 12, o 16 fo the umbe of PMA laes.
  • You ca place the pimay PLL cofiguatio with 2 PMA laes eithe o FGT PMA Lae 1 ad 0 (same quad) of ay quad, with Lae 1 as the pimay. O FGT PMA Lae 3 ad 2 (same quad) of ay quad with lae 3 beig the pimay.
  • You ca place the pimay PLL cofiguatio with 4 PMA laes o FGT PMA Lae 3,2,1 ad 0 (same quad) of ay quad with Lae 3 beig the pimay.
  • Whe you place ay pimay PLL cofiguatio i Quad 2, you caot cofigue efeece clock [8] (accessible by Quad2) as output to povide RX ecoveed clock.
  • Whe you place ay pimay PLL cofiguatio i Quad 3, you caot cofigue efeece clock [9] (accessible by Quad3) as output to povide RX ecoveed clock.
Note: Refe to FGT PLL Cofiguatio i F-tile Achitectue Use Guide fo moe ifomatio.

Tuig the k Coute Value i Factioal Mode

Fo desigs with 1, 2, o 4 PMA laes, you ca cofigue the FGT PMA i factioal mode to adjust the fequecy ad dataate by a small amout fo ate matchig puposes.
  • Whe umbe of PMA laes is 1, tu o Eable TX FGT PLL factioal mode, set PMA efeece clock fequecy as 141 MHz, ad tue the k coute value of the lae.
  • Whe umbe of PMA laes is 2, o 4, tu o Eable TX FGT PLL factioal mode, tu o Eable TX FGT PLL cascade mode, set PMA efeece clock fequecy as 141 MHz, ad tue the k coute value of the pimay lae.
I ode to meet the jitte specificatios of OTN (Optical Taspot Netwok) ad SDI (Seial Digital Iteface), dyamic chages i the factioal value should have the followig limits:
  • Maximum step size: 2.5 ppm
  • Miimum duatio betwee steps: 1 us
If the OTN o SDI jitte specificatios does ot apply to you desig, ad you wat to adjust the data ate without losig lock, the dyamic chages i the factioal value should have the followig limits:
  • Maximum step size: 100 ppm
  • Miimum duatio betwee steps: ukow
Altea ecommeds keepig the duatio as log as you ca affod to get stable pefomace.

Each FGT PMA has a Avalo® memoy-mapped iteface egiste cotaiig the k coute. The k coute / 2^22 gives the factioal value K of the feedback coute. The factioal value K plus the M coute value povides the total feedback coute ad detemies how much PPM each bit i the k coute epesets. Fo example, the LSB (least sigificat bit) i the k coute epesets PPM = (1 / 2^22) / (K+M) × (10^6).

The pocedue to chage the k coute is:

  1. Chage the k coute to the ew value.
  2. Pulse the stobe bit 0 -> 1-> 0 to lock i the ew k coute.

Each FGT PMA cotais 3 PLLs; slow, medium ad fast. FGT PMAs ae ogaized i a quad. The k coute ad stobe bit Avalo® memoy-mapped iteface egiste addesses deped o the locatio of the tasceive i the quad ad which PLL is used (slow, medium, fast) as show i the table below.

Table 80.  FGT PMA Factioal k Coute ad Stobe Registe Addesses
Chael Locatio i Quad PLL Factioal k Coute Registe Stobe Registe
0 Slow 0x44000[30:9] 0x4400C[17]
Medium 0x44100[30:9] 0x4410C[17]
Fast 0x44200[30:9] 0x4420C[17]
1 Slow 0x4C000[30:9] 0x4C00C[17]
Medium 0x4C100[30:9] 0x4C10C[17]
Fast 0x4C200[30:9] 0x4C20C[17]
2 Slow 0x54000[30:9] 0x500C[17]
Medium 0x54100[30:9] 0x5410C[17]
Fast 0x54200[30:9] 0x5420C[17]
3 Slow 0x5C000[30:9] 0x5C00C[17]
Medium 0x5C100[30:9] 0x5C10C[17]
Fast 0x5C200[30:9] 0x5C20C[17]
You ca fid the tasceive locatio ad PLL selected i the <desig_ame>.sy.pt geeated by the Quatus® Pime Po Editio softwae as show i the followig figue.
Figue 84. Sample Quatus® Pime Po Editio Softwae Sythesis Compilatio Result
; z1577a_u_ux_quad_3__ux3_syth_lc_med_e         ; eable                                   ; Stig        ;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_f_out_hz           ; 0000000001010110011011010011111010000000 ; Usiged Biay;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_f_pfd_hz           ; 0000000000000000000000000000000000000000 ; Usiged Biay;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_f_ef_hz           ; 0000000000001000110110011110111000100000 ; Usiged Biay;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_f_x_postdiv_hz    ; 0000000000010001010010010000110010000000 ; Usiged Biay;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_f_tx_postdiv_hz    ; 0000000000000110111010100000010100000000 ; Usiged Biay;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_f_vco_hz           ; 0000001010110011011010011111010000000000 ; Usiged Biay;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_factioal_e      ; eable                                   ; Stig         ;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_k_coute          ; 0000111010100111001110                   ; Usiged Biay;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_l_coute          ; 001000                                   ; Usiged Biay;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_m_coute          ; 000100111                                ; Usiged Biay;
; z1577a_u_ux_quad_3__ux3_syth_lc_med__coute          ; 000001                                   ; Usiged Biay;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_powedow_mode     ; false                                    ; Stig         ;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_pimay_use        ; ux3_syth_lc_med_pimay_use_disabled    ; Stig         ;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_x_postdiv_coute ; 00101000                                 ; Usiged Biay;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_tx_postdiv_coute ; 01100100                                 ; Usiged Biay;
; z1577a_u_ux_quad_3__ux3_syth_lc_med_tx_postdiv_factioal_e ; disable                            ; Stig         ;
I the sample compilatio esult show above, the FGT PMA is placed i quad 3, chael 3 ad the medium PLL is used. The M coute is 39 (000100111) ad the omial K value is 0.057 (0000111010100111001110/2^22). The LSB i the k coute epesets 6 ppb (pats pe billio) (1/2^22/39.057). The k coute egiste addess is 0x5C100[30:9] ad the stobe egiste bit addess is 0x5C10C[17].