Ascent Communication Technology

400G QSFP-DD LR4 1310 nm 10 km

Ascent’s QSFP-DD-400G-LP-10 is a 400 Gb/s Quad Small Form Factor Pluggable-double density (QSFP-DD) optical module designed for 10km optical communication applications. The module converts 8 channels of 50 Gb/s (PAM4) electrical input data to 4 channels of CWDM optical signals, and multiplexes them into a single channel for 400 Gb/s optical transmission. Reversely, on the receiver side, the module optically de-multiplexes a 400 Gb/s optical input into 4 channels of CWDM optical signals, and converts them to 8 channels of 50 Gb/s (PAM4) electrical output data.

• Compliant to QSFP-DD MSA

• 4 CWDM lanes MUX/DEMUX design

• 100G Lambda MSA 400G-LR4 specification compliant

• Duplex LC connector

• Up to 10 km transmission distance on single-mode fiber (SMF) with FEC

• 8 × 53.125 Gb/s electrical interface (400GAUI-8)

• 106.25 Gbps (PAM4) data rate per channel

• Case temperature range: 0 °C to +70 °C

• Max. power consumption 12 W

• RoHS compliant

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
Storage Temperature	T_S	‑40		+85	°C
Operating Case Temperature	T_OP	0		+70	°C
Relative Humidity	RH	0		85	%
Power Supply Voltage	V_CC	‑0.5		3.6	V
Damage threshold, Each Lane	THd	5.0			dBm

Recommended Operating Conditions

Parameter	Symbol	Min.	Typ.	Max.	Unit	Notes
Operating Case Temperature	T_OP	0	‑	+70	°C
Power Supply Voltage	V_CC	3.135	3.3	3.465	V
Data Rate, Each Lane			26.5625		GBd	PAM4
Data Rate Accuracy		‑100		100	ppm
Pre‑FEC Bit Error Ratio				2.4 × 10^‑4
Post‑FEC Bit Error Ratio				1 × 10^‑12		1
Transmission Distance	D	0.002		10	km	2

Notes

1. FEC Provided by host system.

2. FEC required on host system to support maximum distance

Optical Characteristics

Parameter	Symbol	Min	Typ.	Max	Unit	Notes
Wavelength Assignment	L0	1264.5	1271	1277.5	nm
	L1	1284.5	1291	1297.5	nm
	L2	1304.5	1311	1317.5	nm
	L3	1324.5	1331	1337.5	nm
Transmitter
Modulation Format			PAM4
Data Rate, Each Lane		53.125 ± 100 ppm			GBd
Side‑Mode Suppression Ratio	SMSR	30			dB
Total Average Launch Power	P_T			10.0	dBm
Average Launch Power Each Lane		‑2.8			dBm	1
Outer Optical Modulation Amplitude (OMA_outer), Each Lane	P_AVG	0.2		4.2	dBm	2
Launch Power in OMA_outer ‑ TDECQ, Each Lane	P_OMA	‑1.2			dB	ER ≥ 4.5 dB
	P_OMA	‑1.1			dB	ER < 4.5 dB
Transmitter and Dispersion Eye Closure for PAM4, Each Lane	TDECQ			3.9	dB
TDECQ – 10*log₁₀(Ceq), each lane				3.9	dB	3
Extinction Ratio	ER	3.5			dB
Difference in Launch Power between any Two Lanes (OMA_outer)				4	dB
RIN_15.6OMA	RIN			‑136	dB/Hz
Optical Return Loss Tolerance	TOL			15.6	dB
Transmitter Reflectance	R_T			‑26	dB
Transmitter Transition Time				17	ps
Average Launch Power of OFF Transmitter, Each Lane	P_off			‑20	dBm
Receiver
Modulation Format		PAM4
Data Rate, Each Lane		53.125 ± 100 ppm			GBd
Damage Threshold, Each Lane	TH_d	5.0			dBm	4
Average Receive Power, Each Lane		‑9.1		4.0	dBm	5
Receive Power (OMA_outer), Each Lane				4.2	dB
Difference in Launch Power between any Two Lanes (OMA_outer)				4.6	dBm
Receiver Sensitivity (OMA_outer), Each Lane	SEN	Equation (1)			dBm	6
Stressed Receiver Sensitivity (OMA_outer), Each Lane	SRS			‑4.1	dBm	7
Receiver Reflectance	R_R			‑26	dB
LOS De‑Assert	LOSD	‑20			dBm
LOS Assert	LOSA			‑12.1	dBm
LOS Hysteresis	LOSH	0.5			dB
Stressed Conditions for Stress Receiver Sensitivity (Note 8)
Stressed Eye Closure for PAM4 (SECQ), Lane under Test			3.9		dB
SECQ – 10 * log₁₀(Ceq), Lane under Test				3.9	dB
OMA_outer of each Aggressor Lane			0.5		dBm

Notes:

1. Average launch power, each lane (min) is informative and not the principal indicator of signal strength. A transmitter with launch power below this value cannot be compliant; however, a value above this does not ensure compliance.

2. Even if the TDECQ < 1.4 dB for an extinction ratio of 4.5 dB or TDECQ < 1.3 dB for an extinction ratio of <4.5 dB, the OMA_outer (min) must exceed the minimum value specified here.

3. C_eq is a coefficient defined in IEEE Std 802.3‑2018 clause 121.8.5.3 which accounts for reference equalizer noise enhancement.

4. Average receive power, each lane (min) is informative and not the principal indicator of signal strength. A received power below this value cannot be compliant; however, a value above this does not ensure compliance.

5.The receiver shall be able to tolerate, without damage, continuous exposure to an optical input signal having this average power level.

6.Receiver sensitivity (OMA_outer), each lane (max) is informative and is defined for a transmitter with a value of SECQ up to 3.9dB. It should meet Equation (1), which is illustrated in the Illustration of Receiver Sensitivity Mask for 400G‑LR4 seen below.

Equation 1: RS = max(‑6.6, SECQ ‑ 8.0) dBm

Where:

RS is the receiver sensitivity, and

SECQ is the SECQ of the transmitter used to measure the receiver sensitivity.

7. Measured with conformance test signal at TP3 for the BER equal to 2.4 x 10^‑4.

8. These test conditions are for measuring stressed receiver sensitivity. They are not characteristics of the receiver.

Illustration of Receiver Sensitivity Mask for 400G‑LR4

Electrical Characteristics

Parameter	Symbol	Min	Typ.	Max	Unit	Notes
Power Consumption				12	W
Supply Current	Icc			3.64	A
Transmitter (Each Lane)
Signaling Rate, Each Lane	TP1	26.5625 ± 100 ppm			GBd
Differential pk‑pk Input Voltage Tolerance	TP1a	900			mVpp	1
Differential Termination Mismatch	TP1			10	%
Differential Input Return Loss	TP1	IEEE 802.3‑2015 Equation (83E‑5)			dB
Differential to Common Mode Input Return Loss	TP1	IEEE 802.3‑2015 Equation (83E‑6)			dB
Module Stressed Input Test	TP1a	See IEEE 802.3bs 120E.3.4.1				2
Single‑Ended Voltage Tolerance Range (Min.)	TP1a	‑0.4 to 3.3			V
DC Common Mode Input Voltage	TP1	‑350		2850	mV	3
Receiver (Each Lane)
Signaling Rate, Each Lane	TP4	26.5625 ± 100 ppm			GBd
Differential pk‑pk Output Voltage	TP4			900	mVpp
AC Common Mode Output Voltage	TP4			17.5	mV
AC Common Mode Output Voltage, RMS	TP4			10	%
Differential Termination Mismatch	TP4	IEEE 802.3‑2015 Equation (83E‑2)
Differential Output Return Loss	TP4	IEEE 802.3‑2015 Equation (83E‑2)
Common to Differential Mode Conversion Return Loss	TP4	IEEE 802.3‑2015 Equation (83E‑3)
Transition Time, 20 % to 80 %	TP4	9.5			ps
Near‑End Eye Symmetry Mask Width (ESMW)	TP4		0.265		UI
Near‑End Eye Height, Differential	TP4	70			mV
Far‑End Eye Symmetry Mask Width (ESMW)	TP4		0.2		UI
Far‑End Eye Height, Differential	TP4	30			mV
Far‑End Pre‑Cursor ISI Ratio	TP4	‑4.5		2.5	%
Common Mode Output Voltage (Vcm)	TP4	‑350		2850	mV	3

Notes:

1. With the exception to IEEE 802.3bs 120E.3.1.2 that the pattern is PRBS31Q or scrambled idle.

2. Meets BER specified in IEEE 802.3bs 120E.1.1.

3. DC common mode voltage generated by the host. Specification includes effects of ground offset voltage.

Digital Diagnostic Monitoring Information

Parameter	Symbol	Min	Max	Unit	Notes
Temperature Monitor Absolute Error	DMI_Temp	‑3	3	°C	Over operating temperature range
Supply Voltage Monitor Absolute Error	DMI_VCC	‑0.1	0.1	V	Over full operating range
Channel RX Power Monitor Absolute Error	DMI_RX_Ch	‑2	2	dB	1
Channel Bias Current Monitor	DMI_Ibias_Ch	‑10 %	10 %	mA
Channel TX Power Monitor Absolute Error	DMI_TX_Ch	‑2	2	dB	1