Uri Cummings

The design of an asynchronous MIPS R3000 microprocessor

The design of an asynchronous clone of a MIPS R3000 microprocessor is presented. In 0.6 /spl mu/m CMOS, we expect performance close to 280 MIPS, for a power consumption of 7 W. The paper describes the structure of a high-performance asynchronous pipeline, in particular precise exceptions, pipelined caches, arithmetic, and registers, and the circuit techniques developed to achieve high throughput.

An asynchronous pipelined lattice structure filter

We derive an asynchronous, delay-insensitive CMOS circuit to implement a finite impulse response lattice structure filter. Simulation indicates a performance in the range of 380 million multiplications and 980 million additions per second in Hewlett-Packards 0.8 /spl mu/m technology (/spl lambda/=0.5 /spl mu/m). We obtain high throughput by using deep pipelines and buffering the carry chains of adders and multipliers. Our work demonstrates that formal design can easily yield circuits which are safe and fast.

Bandwidth of linearized electrooptic modulators

Many schemes have been proposed to make high dynamic range analog radio frequency (RF) photonic links by linearizing the transfer function of the links modulator. This paper studies the degrading effects of finite transit time and optical and electrical velocity dispersion on such linearization schemes. It further demonstrates that much of the lost dynamic range in some modulators may be regained by segmenting and rephasing the RF transmission line.

Antenna-coupled millimeter-wave electro-optic modulators for 20 to 100 GHz

Coupling the signal to the electrodes of an integrated electro-optical modulator with an array of antennas is used to velocity-match the modulation and optical waves, greatly extending-the length-to-modulation frequency product of the modulator. In addition, antenna coupling eliminates the parasitic elements associated with coax connectors, matching transformers and bond wires. This paper summarizes the results obtained to date with this technique at 20 to 100 GHz, with phase modulators, Mach-Zehnder modulators, and delta-beta directional coupler modulators.

Linearized modulators for analog photonic links

The potential applications of high dynamic range analog RF photonic links include antenna remoting, photonic-coupled phased-array antennas, and cable-television transmission. This paper compares the results obtained with a number of different electro-optic modulator types and link configurations assuming an ideal velocity-matched modulator. The degrading effects of velocity mismatching are also presented for some of the modulators studied.

Effects of velocity mismatch and transit time on linearized electro-optic modulators

The program written for this study allows calculations for periodically-rephased modulators since the modulator is already broken up into a series of incremental matrices. Thus if the modulator is allowed to be mismatched for a few matrices and then rephased for the next few and so on, we have the results shown for a four segment modulator (3 rephasings). modulators are considered.