Loading [MathJax]/extensions/MathMenu.js
Design of a 9-bit SAR ADC for Quad-channel VCSEL Transmitters | IEEE Conference Publication | IEEE Xplore

Design of a 9-bit SAR ADC for Quad-channel VCSEL Transmitters


Abstract:

A 9-bit current-mode SAR ADC for automatic power control of quad-channel vertical-cavity surface-emitting laser (VCSEL) optical transmitter is proposed in this paper. The...Show More

Abstract:

A 9-bit current-mode SAR ADC for automatic power control of quad-channel vertical-cavity surface-emitting laser (VCSEL) optical transmitter is proposed in this paper. The ADC consists of an input selector, a current comparator, a 9-bit current-mode DAC, and clock generation and SAR logic control circuits. The good static characteristics of ADC are mainly implemented by using segmented DAC structure with low mismatch design, and the dynamic characteristics are mainly optimized by lowering the noise of SAR timing sequence. Designed in 130 nm SiGe BiCMOS technology, the ADC occupies an area of 0.05 mm2, and consumes dynamic power of 2.9 mW under 1.8 V power supply. The simulation results show that the DNL and INL are within ±0.27 and ±0.26 LSB, respectively. At Nyquist frequency, its SFDR and ENOB are 50.87 dB and 7.29 bits, respectively.
Date of Conference: 20-23 October 2023
Date Added to IEEE Xplore: 25 December 2023
ISBN Information:
Conference Location: Nanjing, China

Funding Agency:


I. Introduction

With the rapid growth of data throughput in various industries, quad-channel optical transmitters has been widely studied and used for 100G to 400G optical communication applications. In these systems, ADC plays an important role in detecting working conditions based on some voltage or current parameters [1]. Vertical-cavity surface-emitting laser (VCSEL) is a typical directly modulated laser (DML). It has a positively biased PN junction structure which generates stimulated emission by a bias current and outputs optical signal by a modulation current [2]. However, the static optical power varies with temperature and device aging, which requires an automatic power control (APC) method to maintain the desired working condition [3]. One typical method is to use a monitor photodiode (mPD) to generate a current signal proportional to the output power of VCSEL. An ADC is integrated in the VCSEL transmitter to measure the current signal for subsequent control of VCSEL bias current through digital logic circuits and DACs.

References

References is not available for this document.