Synchronous OEIC integrating receiver for optically reconfigurable gate arrays

A monolithically integrated optoelectronic receiver with a low-capacitance on-chip pin photodiode is presented. The receiver is fabricated in a 0.35µm opto-CMOS process fed at 3.3V and due to the highly effective integrated pin photodiode it operates at µW. A regenerative latch acting as a sense amplifier leads in addition to a low electrical power consumption. At 400 Mbit/s, sensitivities of -26.0dBm and -25.5dBm are achieved, respectively, for ¿ = 635nm and ¿ = 675nm (BER =10-9) with an energy efficiency of 2 pJ/bit

Synchronous OEIC integrating receiver for ORGA applications

This work presents a monolithically integrated synchronous optical receiver fabricated in a standard 0.35 mu m CMOS process. The receiver consists of a regenerative latch acting as a sense amplifier; two highly effective, low-capacitance pin photodiodes connected to its output nodes (one of them blocked to the light); and an adjustable reference current to compensate the dynamic offset created by the asymmetries between the parasitic capacitances of the photodiodes. For lambda = 635 nm, a sensitivity of -25.8 dBm, -26.0 dBm, and -28.4dBm is obtained, respectively, for 400 Mbit/s, 350 Mbit/s, and 250 Mbit/s (BER = 10(-9)). The power consumption is 670 mu W, which translates to an energy efficiency of 1.7 pJ/bit at 400 Mbit/s

Parallel reconfigurable single photon avalanche diode array for optical communications

There is a pressing need to develop alternative communications links due to a number of physical phenomena, limiting the bandwidth and energy efficiency of wire-based systems or economic factors such as cost, material-supply reliability and environmental costs. Networks have moved to optical connections to reduce costs, energy use and to supply high data rates. A primary concern is that current optical-detection devices require high optical power to achieve fast data rates with high signal quality. The energy required therefore, quickly becomes a problem. In this thesis, advances in single-photon avalanche diodes (SPADs) are utilised to reduce the amount of light needed and to reduce the overall energy budget. Current high performance receivers often use exotic materials, many of which have severe environmental impact and have cost, supply and political restrictions. These present a problem when it comes to integration; hence silicon technology is used, allowing small, mass-producible, low power receivers. A reconfigurable SPAD-based integrating receiver in standard 130nm imaging CMOS is presented for links with a readout bandwidth of 100MHz. A maximum count rate of 58G photon/s is observed, with a dynamic range of ≈ 79dB, a sensitivity of ≈ −31.7dBm at 100MHz and a BER of ≈ 1x10−9. We investigate the properties of the receiver for optical communications in the visible spectrum, using its added functionality and reconfigurability to experimentally explore non-ideal influences. The all-digital 32x32 SPAD array, achieves a minimum dead time of 5.9ns, and a median dark count rate (DCR) of 2.5kHz per SPAD. High noise devices can be weighted or removed to optimise the SNR. The power requirements, transient response and received data are explored and limiting factors similar to those of photodiode receivers are observed. The thesis concludes that data can be captured well with such a device but more electrical energy is needed at the receiver due to its fundamental operation. Overall, optical power can be reduced, allowing significant savings in either transmitter power or the transmission length, along with the advantages of an integrated digital chip

Center for space microelectronics technology

The 1992 Technical Report of the Jet Propulsion Laboratory Center for Space Microelectronics Technology summarizes the technical accomplishments, publications, presentations, and patents of the center during the past year. The report lists 187 publications, 253 presentations, and 111 new technology reports and patents in the areas of solid-state devices, photonics, advanced computing, and custom microcircuits

A low-voltage CMOS-compatible time-domain photodetector, device & front end electronics

During the last decades, the usage of silicon photodetectors, both as stand-alone sensor or integrated in arrays, grew tremendously. They are now found in almost any application and any market range, from leisure products to high-end scientific apparatuses, including, among others, industrial, automotive, and medical equipment. The impressive growth in photodetector applications is closely linked to the development of CMOS technology, which now offers inexpensive and efficient analog and digi-tal signal processing capabilities. Detectors are often integrated with their respective front end and application-specific digital circuit on the same silicon die, forming complete systems on chip. In some cases the detector itself is not on the same chip but often part of the same package. However, this trend of co-integration of analog front end and digital circuits complicates the design of the analog part. The ever-decreasing supply voltage and the smaller transistors in advanced processes (which are driven by the development of digital cir-cuits) negatively impact the performance of the analog structures and complicates their design. For photodetector systems, the effect most importantly translates into a degradation of dynamic range and signal-to-noise ratio. One way to circumvent the problem of low supply voltages is to shift the operation from voltage domain to time domain. By doing so, the signal is no longer constrained by the supply rails and analog amplification is avoided. The signal takes the form of a time-based modulation, such as pulse-width modulation or pulse-frequency modulation. Another advantage is that the output signal of a time-domain photodetection system is directly interfaceable with digital circuits. In this work, a new type of CMOS-compatible photodetector displaying intrinsic light-to-time conversion is proposed. Its physical structure consists of a MOS gate interleaved with a PN junction. The MOS structure is acting as a photogate. The depletion region shrinks when photogenerated carriers fill the potential well. At some point, the anode of the PN structure is de-isolated from the rest of the detector and triggers a positive-feedback effect that leads to a very steep current increase through the PN-junction. This translates into a signal of very high amplitude and independent from light-intensity, which can be almost directly interfaced with digital circuits. This simplifies the front end circuit compared to photodiode-based systems. The physical behavior of the device is analyzed with the help of TCAD simulations and simple behavioral and shot-noise models are proposed. The device has been co-integrated with its driver and front end circuit in a standard CMOS process and its characteristics have been measured with a custom-made measurement system. The effect of bias parameters on the performance of the sensor are also analyzed. The limitations of the device are discussed, the most important ones being dark current and linearity. Techno-logical solutions, such as the implementation of the detector on Silicon-on-Insulator technology, are proposed to overcome the limitations. Finally, some application demonstrators have been realized. Other applications that could benefit from the detector are suggested, such as digital applications taking advantage of the latching behavior of the device, and a Photoplethysmography (PPG) system that uses a PLL-based control loop to minimize the emitting LED-current

Optical Communication

Optical communication is very much useful in telecommunication systems, data processing and networking. It consists of a transmitter that encodes a message into an optical signal, a channel that carries the signal to its desired destination, and a receiver that reproduces the message from the received optical signal. It presents up to date results on communication systems, along with the explanations of their relevance, from leading researchers in this field. The chapters cover general concepts of optical communication, components, systems, networks, signal processing and MIMO systems. In recent years, optical components and other enhanced signal processing functions are also considered in depth for optical communications systems. The researcher has also concentrated on optical devices, networking, signal processing, and MIMO systems and other enhanced functions for optical communication. This book is targeted at research, development and design engineers from the teams in manufacturing industry, academia and telecommunication industries