LOCld65, A Dual-Channel VCSEL Driver ASIC For Detector Front-End Readout

TL;DR

LOCld65 is a dual-channel VCSEL driver ASIC designed in 65-nm CMOS, capable of 14 Gbps operation, with programmable features and radiation tolerance, suitable for high-energy physics detector readout systems.

Contribution

This paper introduces LOCld65, a novel dual-channel VCSEL driver ASIC with integrated programmable features, radiation protection, and high-speed operation tailored for detector front-end readout.

Findings

Operates up to 14 Gbps per channel

Power consumption of approximately 62-68 mW per channel

Survives radiation doses up to 4.9 kGy(SiO2)

Abstract

We present the design and the test results of a dual-channel Vertical-Cavity Surface-Emitting Laser (VCSEL) driver ASIC LOCld65 for detector front-end readout. LOCld65 is designed in a commercial 65-nm CMOS technology with a power supply of 1.2 V. LOCld65 contains two separate channels with the same structure and the two channels share an I2C slave. Each channel consists of an input amplifier, four stages of limiting amplifiers (LAs), a high-current output driver, and a bias-current generator. In order to extend the bandwidth, the input amplifier uses an inductive peaking technique and the LAs use a shared inductive peaking technique. The input amplifier and the output driver each utilize a Continuous-Time Linear Equalizer (CTLE). The LAs employ active feedback. The modulation current, the bias current, the peaking strength of the CTLEs, and the feedback strength of LAs are programmable through an I2C interface. In order to protect from the radiation damage, the I2C slave is implemented with triple modular redundancy. Each channel of LOCld65 is tested to operate up to 14 Gbps with typical power dissipations (the VCSEL included) of 68.3 mW/channel and 62.1 mW/channel at the VCSEL voltages of 3.3 V and 2.5 V, respectively. LOCld65 survives 4.9 kGy(SiO2). LOCld65 is an excellent match for the serializer-deserializer ASIC lpGBT in single- or dual-channel optical transmitters in HL-LHC upgrade applications.