QSFP-DD 400GE SR8 100 m Optical Transceiver Module

QSFP-DD 400GE SR8 100 m Optical Transceiver Module


ETSC’s OM3680SX200 is a parallel 400GE Quad Small Form Factor Pluggable double density (QSFP-DD) SR8 optical module designed for optical communication applications. The optical module uses a 4- level pulse amplitude modulation (PAM4) format. The optical module provides point-to-point 400 Gigabit Ethernet links over eight pairs of multimode fiber, with a reach of up to 100 m for OM4 (MMF) and 70 m for OM3 (MMF).

It is compliant with QSFP-DD MSA standard and IEEE 802.3cm 400GBASE-SR8 standard and IEEE 802.3bs 400GAUI-8 standard. Digital diagnostics functions are available via the I2C interface, as specified by the QSFP-DD MSA.


  • QSFP-DD MSA compliant
  • QSFP-DD CMIS4.0 Management interface compliant
  • IEEE 802.3cm 400GBASE-SR8 standard compliant
  • IEEE 802.3bs 400GAUI-8 standard compliant
  • Digital diagnostic functions
  • 8 channels full-duplex transceiver module
  • 425 Gbit/s aggregate bit rate
  • Maximum link length of 70 m OM3, 100 m OM4 with FEC
  • Single MPO-16/APC receptacle
  • Maximum power dissipation < 10 W
  • Operating case temperature range 0 to 70℃
  • Single 3.3 V power supply
  • RoHS 2.0 compliant


  • 400G Ethernet
  • Data center network

Absolute Maximum Ratings

It has to be noted that the operation in excess of any individual absolute maximum ratings might cause permanent damage to this module.

Parameter Symbol Min Typ Max Unit Notes
Maximum supply voltage Vcc -0.3 3.3 3.6 V
Storage temperature Ts -40 85
Relative humidity RH 5 85 % 1
Damage threshold, each lane THd 5 dBm
  1. Non-condensing.

Operating Environments

Electrical and optical characteristics below are defined under this operating environment, unless otherwise specified.

Parameter Symbol Min Typ Max Unit Notes
Supply voltage Vcc 3.135 3.3 3.465 V
Case temperature Tc 0 70
Data rate, each lane 26.5625 GBd
Data rate accuracy -100 100 ppm
Modulation format PAM4
Link distance with OM3 MMF 70 m
Link distance with OM4 MMF 100 m
Link distance with OM5 MMF 100 m
  1. Initialization Flows: The Host Initialization Flows of CMIS Rev4.0 Standard Appendix C are recommended.

Electrical Characteristics

Parameter Symbol Min Typ Max Unit Notes
Power dissipation 9 10 W
Steady state current Icc 3189 mA 1
Instantaneous peak current 4000 mA
Sustained peak current 3300 mA
Module-to-Host electrical specifications at TP4 (module output)
Differential voltage pk-pk Vpp 900 mV
Common mode voltage Vcm -350 2850 mV 2
AC common-mode output voltage  (RMS) 17.5 mV
Parameter Symbol Min Typ Max Unit Notes
Transition time Trise/Tfall 9.5 ps 20%~80%
Differential termination resistance  mismatch 10 %
Near-end ESMW (eye symmetry  mask width) 0.265 UI
Near-end eye height, differential 70 mV
Far-end ESMW (eye symmetry  mask width) 0.20 UI
Far-end eye height, differential 30 mV
Far-end pre-cursor ISI ratio -4.5 2.5 %
Differential output return loss IEEE 802.3-2018 Equation  (83E-2) dB
Common to differential mode con- version return loss IEEE 802.3-2018 Equation  (83E-3) dB
Host-to-Module electrical specifications (module input)
Differential termination resistance  mismatch 10 %
Overload differential voltage pk-pk Vpp 900 mV TP1a
DC common mode voltage Vcm -350 2850 mV TP1
Single-ended voltage tolerance -0.4 3.3 V TP1a
Module stressed input test IEEE 802.3bs 120E.3.4.1 TP1a
Differential input return loss IEEE 802.3-2018 Equation  (83E-5) dB TP1
Differential to common mode input  return loss IEEE 802.3-2018 Equation  (83E-6) dB TP1
  1. The module must stay within its declared power class.
  2. DC common mode voltage is generated by the host. Specification includes effects of ground offset voltage.

Optical Characteristics

Parameter Symbol Min Typ Max Unit Notes
Center wavelength λc 840 868 nm
Host-to-Module electrical specifications (module input)
RMS spectral width 0.65 nm
Average launch power, each lane PAVG -6.5 4 dBm
Outer optical modulation amplitude  (OMA outer), each lane POMA -4.5 3 dBm
Launch power in OMA outer minus  TDECQ, each lane -5.9 dBm
Transmitter and dispersion eye clo-  sure for PAM4, each lane TDECQ 4.5 dB
TDECQ – 10log10 (Ceq), each lane 4.5 dB
Extinction ratio, each lane ER 3 dB
Transmitter transition time, each  lane 34 ps
Average launch power of OFF  transmitter, each lane POFF -30 dBm
RIN12OMA -128 dB/Hz
Optical return loss tolerance 12 dB
Encircled flux ≥ 86% at 19 um ≤ 30% at 4.5 um Encircled flux
Average receiver power, each lane -8.4 4 dBm
Receiver power, each lane (OMA) 3 dBm
Damage threshold, each lane THd 5 dBm
Receiver reflectance -12 dB
LOS assert LosA -24.6 dBm
LOS de-assert LosD -8 dBm
LOS hysteresis LosH 0.5 dB
Receiver sensitivity (OMA outer),  each lane Sen Max (– 6.5,SE  CQ –7.9) dB
Stressed receiver sensitivity  (OMA) , each lane SRS -3.4 dBm
Conditions of stressed receiver sensitivity test
Stressed eye closure for PAM4,  lane under test SECQ 4.5 dB
SECQ – 10log10 (Ceq), lane under  test 4.5 dB
OMA outer of each aggressor lane 3 dBm