112 GBaud (224 Gb/s) large output swing InP DHBT PAM-4 DAC-driver

In this paper, we report on the design, optimisation and and electrical measurements of a PAM-4 DAC-driver fabricated in 0.7-μm InP/GaAsSb DHBT technology, with the capability to directly drive an electro-optical modulator. Circuit measurements in PAM-4 mode show high diagram quality at 90 GBaud (180 Gb/s) with a record 5.5–V
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differential output swing. An over 12-dB gain control capability is shown. Moreover, a record 3.35-V
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output swing is obtained in PAM-4 at 112 GBaud (224 Gb/s). Power consumption is 1.1 and 0.6 W for two operating symbol-rates respectively.