Ascent Communication Technology

400G QSFP-DD ER8 40 km

Ascent’s QSFP-DD-ER8-40 is a 400 Gb/s Quad Small Form Factor Pluggable-double density (QSFP-DD) optical module designed for 40 km optical communication applications. It converts 8x 50G 400GAUI-8 PAM4 (Pulse-Amplitude Modulation) electrical input channels (each 53.125Gbps) into 8 Single Lambda 50G PAM4 LAN-WDM optical signals which are multiplexed for transmission over single fiber. On the receiver side, the optical signal is received and de-multiplexed and then QSFP-DD ER8 transceiver converts 8 Single Lambda 50G PAM4 LAN-WDM optical signals into 8x 50G 400GAUI-8 electrical inputs.

• Compliant with IEEE std 802.3cnTM-2019:

• 400GBASE-ER8 optical interface

• 400GAUI-8 electrical interface

• Compliant with QSFP-DD MSA HW Rev 5.1 with duplex LC connector

• Compliant with QSFP-DD CMIS Rev 4.0

• Case operating temperature 0°C to 70°C

• Two wire serial Interface with digital diagnostic monitoring

• Complies with EU Directive 2011/65/EU (RoHS compliant)

• Class 1/1M Laser

Absolute Maximum Ratings

Parameter	Symbol	Min.	Max.	Unit	Note
Storage Temperature	T_S	‑40	85	°C
Supply Voltage	V_CC	‑0.5	3.6	V
Relative Humidity (non‑condensing)	RH	5	95	%	Non‑condensing
Data Input Voltage Differential	lV_DIP‑V_DINl	‑	1	V
Control Input Voltage	V_I	‑0.3	V_CC+0.5	V
Control Output Voltage	V_O	‑20	20	V

Recommended Operating Conditions

Parameter	Symbol	Min.	Typ.	Max.	Unit	Note
Operating Case Temperature	T_OPR	0	‑	70	°C
Power Supply Voltage	V_CC	3.135	3.3	3.465	V
Instantaneous Peak Current at Hot Plug	I_{CC_IP}	‑	‑	5600	mA
Sustained Peak Current at Hot Plug	I_{CC_SP}	‑	‑	4620	mA
Maximum Power Dissipation	P_D	‑	‑	14	W
Maximum Power Dissipation, Low Power Mode	P_DLP	‑	‑	1.5	W
Signaling Rate per Lane	SRL	‑	26.5625	‑	GBd
Control Input Voltage High	V_IH	V_CC*0.7	‑	V_CC+0.3
Control Input Voltage Low	V_IL	‑0.3	‑	V_CC*0.3
Two Wire Serial Interface Clock Rate	‑	‑	‑	400	kHz
Power Supply Noise Tolerance	‑	‑	‑	66	mV
Rx Differential Data Output Load	‑	‑	100	‑	Ω
Operating Distance	‑	0.002	‑	40	km	1

Notes:

1. Channel insertion loss is 18 dB for 40 km

Transmitter Optical Characteristics

Parameter	Symbol	Min.	Typ.	Max.	Unit	Note
Wavelength L0	λ_C0	1272.55	1273.55	1274.54	nm
Wavelength L1	λ_C1	1276.89	1277.89	1278.89	nm
Wavelength L2	λ_C2	1281.25	1282.26	1283.27	nm
Wavelength L3	λ_C3	1285.65	1286.67	1287.68	nm
Wavelength L4	λ_C4	1294.53	1295.56	1296.59	nm
Wavelength L5	λ_C5	1299.02	1300.06	1301.09	nm
Wavelength L6	λ_C6	1303.54	1304.59	1305.63	nm
Wavelength L7	λ_C7	1308.09	1309.14	1310.19	nm
Side Mode Suppression Ratio	SMSR	30	‑	‑	dB
Total Average Launch Power	AOP_T	‑	‑	14.6	dBm
Average Launch Power, each Lane	AOP_L	‑0.6	‑	5.6	dBm	1
Outer Optical Modulation Amplitude (OMA_outer), each Lane	T_OMA	2.4	‑	6.4	dBm
Difference in Launch Power between any Two Lanes (OMA_outer)	D_{T_OMA}	‑	‑	4	dB
Launch Power in OMAouter minus TDECQ, each Lane	T_OMA‑TDECQ	1	‑	‑	dBm
Transmitter and Dispersion Eye Closure for PAM4 (TDECQ), each Lane	TDECQ	‑	‑	3.4	dB
TDECQ –10log10(Ceq)	‑	‑	‑	3.4	dB
Average Launch Power of OFF Transmitter, each Lane	T_OFF	‑	‑	‑30	dBm
Extinction Ratio	ER	6	‑	‑	dB
RIN₁₅OMA	RIN	‑	‑	‑132	dB/Hz
Optical Return Loss Tolerance	ORL	‑	‑	15	dB
Transmitter Reflectance	T_R	‑	‑	‑26	dB	2

Notes:

1. Average launch power, each lane (min) is informative and not the principal indicator of signal strength

2. Transmitter reflectance is defined looking into the transmitter

Receiver Optical Characteristics

Parameter	Symbol	Min.	Typ.	Max.	Unit	Note
Wavelength L0	λ_C0	1272.55	1273.55	1274.54	nm
Wavelength L1	λ_C1	1276.89	1277.89	1278.89	nm
Wavelength L2	λ_C2	1281.25	1282.26	1283.27	nm
Wavelength L3	λ_C3	1285.65	1286.67	1287.68	nm
Wavelength L4	λ_C4	1294.53	1295.56	1296.59	nm
Wavelength L5	λ_C5	1299.02	1300.06	1301.09	nm
Wavelength L6	λ_C6	1303.54	1304.59	1305.63	nm
Wavelength L7	λ_C7	1308.09	1309.14	1310.19	nm
Damage Threshold, each Lane	AOP_D	‑3.4	‑	‑	dBm
Average Receive Power, each Lane	AOP_R	‑18.6	‑	‑4.4	dBm
Receive Power (OMA_outer), each Lane	OMA_R	‑	‑	‑3.6	dBm
Difference in Receive Power between any Two Lanes (OMA_outer)	D_{R_OMA}	‑	‑	5.8	dB
Receiver Reflectance	RR	‑	‑	‑26	dB
Receiver Sensitivity (OMA_outer), each Lane	S_OMA	‑	‑	Max(–16.1, SECQ – 17.5)	dBm	1
Stressed Receiver Sensitivity (OMA_outer), each Lane	SRS	‑	‑	‑14.1	dBm	2
Conditions of Stressed Receiver Sensitivity Test
Stressed Eye Closure for PAM4 (SECQ), Lane Under Test	‑	‑	3.4	‑	dB
SECQ – 10log10(Ceq), Lane Under Test			‑	3.4	dB
OMA_outer of each Aggressor Lane	‑	‑	‑8.3	‑	dBm

Notes:

1. Receiver sensitivity (OMA_outer), each lane (max) is informative and is defined for a transmitter with SECQ of 1.4 dB.

2. Measured with conformance test signal at TP3 for the BER = 2.4 x 10^‑4

Electrical Specification High Speed Signal (Compliant with IEEE 802.3bs 400GAUI‑8)

Parameter	Symbol	Min.	Typ.	Max.	Unit	Notes
Receiver (Module Output)
AC Common‑Mode Output Voltage (RMS)		‑	‑	17.5	mV
Differential Output Voltage		‑	‑	900	mV
Near‑End Eye Height, Differential		70	‑	‑	mV
Far‑End Eye Height, Differential		30	‑	‑	mV
Far End Pre‑Cursor Ratio		‑	‑	2.5	%
Differential Termination Mismatch		‑	‑	10	%
Transition Time (Min., 20% To 80%)		9.5	‑	‑	ps
DC Common Mode Voltage		‑350	‑	2850	mV
Transmitter (Module Input)
Differential pk‑pk Input Voltage Tolerance		900	‑	‑	mV
Differential Termination Mismatch		‑	‑	10	%
Single‑Ended Voltage Tolerance Range		‑0.4	‑	3.3	V
DC Common Mode Voltage		‑350	‑	2850	mV

Electrical Specification Low Speed Signal (compliant with QSFP‑DD HW Rev 5.1)

Parameter	Symbol	Min.	Max.	Unit	Note
Module Output SCL and SDA	V_OL	0	0.4	V
Module Input SCL and SDA	V_IL	‑0.3	V_CC*0.3	V
	V_IH	V_CC*0.7	V_CC+0.5	V
InitMode, ResetL, and ModSelL	V_IL	‑0.3	0.8	V
	V_IH	2	V_CC+0.3	V
IntL	V_OL	0	0.4	V
	V_OH	V_CC‑0.5	V_CC+0.3	V

Timing for Soft Control and Status Functions

Parameter	Symbol	Min.	Max.	Unit	Note
MgmtInit Duration		‑	2000	ms
ResetL Assert Time	t_reset_init	10	‑	µs
IntL Assert Time	ton_IntL	‑	200	ms
IntL Deassert Time	toff_IntL	‑	500	µs
Rx LOS Assert Time	ton_losf	‑	100	ms
Flag Assert Time	ton_flag	‑	200	ms
Mask Assert Time	ton_mask	‑	100	ms
Mask Deassert Time	toff_mask	‑	100	ms
Module Select Wait Time	ModSelL Wait Time	‑	N/A		Not supported

I/O Timing for Squelch and Disable

Parameter	Symbol	Min.	Max.	Unit	Notes
Rx Squelch Assert Time	ton_Rxsq	‑	50	ms
Tx Squelch Assert Time	ton_Txsq	‑	400	ms
Tx Squelch Deassert Time	toff_Txsq	‑	1500	ms	Based on modulation
Tx Disable Assert Time (fast mode)	ton_Txdisf	‑	3	ms
Tx Disable Deassert Time (fast mode)	toff_Txdisf	‑	10	ms
Rx Output Disable Assert Time	ton_Rxdis	‑	100	ms
Rx Output Disable Deassert Time	toff_Rxdis	‑	100	ms
Squelch Disable Assert Time	ton_sqdis	‑	N/A	ms	Not supported
Squelch Disable Deassert Time	toff_sqdis	‑	N/A	ms	Not supported

Digital Diagnostics

Parameter	Range	Accuracy	Unit	Calibration
Temperature	0 to 70	±3	°C	Internal
Voltage	0 to V_CC	0.1	V	Internal
Tx Bias Current (Each Lane)	0 to 100	10 %	mA	Internal
Tx Output Power (Each Lane)	‑0.6 to +5.6	±3	dB	Internal
Rx Receive Power (Each Lane)	‑18.6 to ‑4.4	±3	dB	Internal