A 6-bit, 4 GSa/s ADC fabricated in a GaAs HBT process

Poulton, K.; Knudsen, K.L.; Corcoran, J.J.; Wang, Keh-Chung; Nubling, R.B.; Pierson, R.; Chang, M.-C. Frank; Asbeck, P.M.; Huang, Rong‐Ting

doi:10.1109/gaas.1994.636976

Cited by 20 publications

(2 citation statements)

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“…A survey of A/D conversion systems conducted by Walden highlights this problem, indicating that most high-speed systems' performance corresponds to a phase error value 500 fs [2]. As an alternative, research on GaAs-and InP-based circuits for mixed-signal systems has occurred in order to take advantage of the higher speed of III-V technologies, but advances have been slow, with the additional drawback of high power consumption for these systems [4]- [6].…”

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confidence: 99%

Photonic A/D conversion using low-temperature-grown gaas msm switches integrated with Si-CMOS

Urata

Nathawad²,

Takahashi

et al. 2003

J. Lightwave Technol.

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By linking the unique capabilities of photonic devices with the signal processing power of electronics, photonically sampled analog-to-digital (A/D) conversion systems have demonstrated the potential for superior performance over all-electrical A/D conversion systems. We adopt a photonic A/D conversion scheme using low-temperature (LT)-grown GaAs metal-semiconductor-metal (MSM) photoconductive switches integrated with Si-CMOS A/D converters. The large bandwidth of the LT GaAs switches and the low timing jitter and short width of mode-locked laser pulses are combined to accurately sample input frequencies up to several tens of gigahertz. CMOS A/D converters perform back-end digitization, and time-interleaving is used to increase the total sampling rate of the system. In this paper, we outline the development of this system, from optimization of the LT GaAs material, speed and responsivity measurements of the switches, bandwidth and linearity characterization of the first-stage optoelectronic sample-and-hold, to integration of the switches with CMOS chips. As a final proof-of-principle demonstration, a two-channel system was fabricated with LT GaAs MSM switches flip-chip bonded to CMOS A/D converters. When operated at an aggregate sampling rate of 160 megasamples/s, the prototype system exhibits 3.5 effective number of bits (ENOB) of resolution for input signals up to 40 GHz. Index Terms-Photonic analog-to-digital (A/D) conversion, low-temperature (LT)-grown GaAs, metal-semiconductor-metal (MSM) devices, optical data processing, sample-and-hold circuits. I. INTRODUCTION W ITH rapidly increasing signal bandwidths along with the predominance of digital technologies and techniques, the need for higher speed analog-to-digital (A/D) conversion arises in order to interface between the analog and digital domains. Applications for A/D conversion at tens of gigasamples/s

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mentioning

confidence: 99%

Photonic A/D conversion using low-temperature-grown gaas msm switches integrated with Si-CMOS

Urata

Nathawad²,

Takahashi

et al. 2003

J. Lightwave Technol.

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“…Fig. 5 presents a chip photograph of an integrated 6-bit 4-GS/s flash ADC, implemented with GaAs HBTs [25]. An InP HBT 3-bit flash ADC has been fabricated, which operates up to 18 GS/s, with 1.7 effective bits over the full Nyquist bandwidth.…”

Section: B Analog-to-digital Converters (Adcs)mentioning

confidence: 99%

Digital signal processing - up to microwave frequencies

Asbeck

Galton

Wang³

et al. 2002

IEEE Trans. Microwave Theory Techn.

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Digital logic integrated circuits are advancing toward ever higher speeds of operation. Clock frequencies already exceed 1 GHz in some Si CMOS-based consumer products, and even higher speeds are attainable in specialized technologies, such as those based on GaAs, InP, and SiGe bipolar and field-effect transistors. Digital approaches may be used to carry out a variety of functions important in microwave systems, including signal generation, filtering, and frequency conversion. The digital implementation provides a variety of potential benefits, including lack of sensitivity to aging and component inaccuracies, flexibility, and programmability. The dynamic range and degree of nonlinearity can be specified by design. Signal storage and memory functions are easily accomplished. Single-chip integration of digital and microwave systems are also facilitated. The application of digital techniques in domains previously considered to be analog is an important ongoing technology thrust, which may be expected to accelerate. Critical interfaces between the digital and analog domains are provided by analog-to-digital converters, digital-to-analog converters, and fractional-frequency synthesizers. This paper reviews the prospects of digital techniques for microwave systems, and briefly describes the state-of-technology and future possibilities. Index Terms-Analog-to-digital conversion, digital signal processing, digital-to-analog conversion, high-speed digital integrated circuits. I. INTRODUCTION S IGNAL processing (including amplification, filtering, frequency generation, frequency conversion, and modulation) at microwave frequencies has traditionally been carried out with analog circuits. However, digital circuits are steadily advancing in capabilities. The technology advances promise to allow digital techniques to be used at frequencies well into the microwave region.

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