A DC to 40 GHz, High Linearity Monolithic GaAs Distributed Amplifier with Low DC Power Consumption as a High Bit-Rate Pre-Driver

This paper presents the design and the performance of a six stage GaAs MMIC distributed amplifier (DA) for optical driver applications. The DA is fabricated in a commercially available 0.15 µm GaAs p-HEMT technology. The amplifier exhibits 13 dB of small gain over 40 GHz of 3 dB bandwidth with a power consumption equal to 550 mW. Group delay time variation up to 30 GHz is only ±7 ps. The output power is higher than 16 dBm (4 Vpp), which makes the circuit suitable as a preamplifier for lithium-niobate (LiNbO3) optical modulator driver. The DA is demonstrated as a part of the modulator driver in a 12.5 GBps PAM-4 (25Gbps) optical system by using the eye diagram as a figure of merit.