Analog Devices

About: Analog Devices is a company organization based out in Norwood, Massachusetts, United States. It is known for research contribution in the topics: Signal & Amplifier. The organization has 3986 authors who have published 5715 publications receiving 84695 citations. The organization is also known as: Analog Devices, Inc..

Impedance specifications for stable DC distributed power systems

Abstract: In a DC distributed power system, the interaction between individually designed power modules/subsystems may cause the instability of the whole system. In a small-signal sense, system level stability is determined by the impedance ratio Z/sub o//Z/sub i/. Here, Z/sub o/ is the output impedance of the source module/subsystem, and Z/sub i/ is the input impedance of the load module/subsystem. As a result, an effective way to prevent system instability is defining impedance specifications for modules/subsystems. This paper briefly summarizes existing works and introduces the authors' contribution in defining impedance specifications. A new forbidden region for impedance ratio Z/sub o//Z/sub i/ on the S-plane is proposed as the system stability margin requirement. Based on this proposed forbidden region, the impedance specifications of individual loads are established. Further, a very practical measurement approach is developed to examine whether or not the system stability margin requirement of the forbidden region is satisfied.

A simple three-terminal IC bandgap reference

Abstract: A new configuration for realization of a stabilized bandgap voltage is described. The new two-transistor circuit uses collector current sensing to eliminate errors due to base current. Because the stabilized voltage appears at a high impedance point, the application to circuits with higher output voltage is simplified. Incorporation of the new two-transistor cell in a three-terminal 2.5-V monolithic reference is described. The complete circuit is outlined in functional detail together with analytical methods used in the design. The analytical results include sensitivity coefficients, gain and frequency response parameters, and biasing for optimum temperature performance. The performance of the monolithic circuit, which includes temperature coefficients of 5 ppm//spl deg/C over the military temperature range, is reported.

Translinear circuits: a proposed classification

Abstract: An important and expanding branch of analogue circuits is the `translinear? group. Their primary function arises from the exploitation of the precise proportionality of transconductance to collector current in bipolar transistors so as to result in fundamentally exact, temperature-insensitive behaviour. The basic translinear principle is derived and several examples given.

A 27-mW CMOS fractional-N synthesizer using digital compensation for 2.5-Mb/s GFSK modulation

Abstract: A digital compensation method and key circuits are presented that allow fractional-N synthesizers to be modulated at data rates greatly exceeding their bandwidth. Using this technique, a 1.8-GHz transmitter capable of digital frequency modulation at 2.5 Mb/s can be achieved with only two components: a frequency synthesizer and a digital transmit filter. A prototype transmitter was constructed to provide proof of concept of the method; its primary component is a custom fractional-N synthesizer fabricated in a 0.6-/spl mu/m CMOS process that consumes 27 mW. Key circuits on the custom IC are an on-chip loop filter that requires no tuning or external components, a digital MASH /spl Sigma/-/spl Delta/ modulator that achieves low power operation through pipelining, and an asynchronous, 64-modulus divider (prescaler). Measurements from the prototype indicate that it meets performance requirements of the digital enhanced cordless telecommunications (DECT) standard.

27.6% Conversion efficiency, a new record for single-junction solar cells under 1 sun illumination

Abstract: Alta Devices, Inc. has fabricated a thin-film GaAs device on a flexible substrate with an independently-confirmed solar energy conversion efficiency of 27.6%, under AM1.5G solar illumination at 1 sun intensity. This represents a new record for single-junction devices under non-concentrated sunlight. This surpasses the previous record, for conversion efficiency of a single-junction device under non-concentrated light, by more than 1%. This is due largely to the high open-circuit voltage (V oc ) of this device. The high V oc results from precise control of the dark current. The fact that this record result has been achieved with a thin-film shows that, for GaAs material systems, the majority of the growth substrate is not needed for device performance. This allows one to consider amortizing the potentially high cost of a GaAs growth substrate by growing a thin-film, lifting it off, and reusing the same substrate multiple times. This technology therefore has the potential to be a novel high-performance, thin-film option for terrestrial photovoltaics.