Hewlett-packard Company

Hewlett-packard Corporation

William J Anklam

Chung-Yi Su

Michael R Tan

William E Kunz

Michael R Ty Tan

Alan R Bloom

David J Schwartz

A digital baseband modulator having a flexible architecture that is readily adaptible to a variety of digital modulation types is provided. A symbol builder maps the input data to a series of modulation states corresponding to data symbols that are represented as state indexes. A pair of digital filters accepts the state indexes being generated by the symbol builder to provide both up-sampling and filtering functions. The digital filters are implemented using random access memory (RAM) to implement blocks of interpolating look-up multipliers which may be readily configured between fast, normal, and long modes. The filtered output data from the digital filters is provided to a resampler that converts the filtered output data to an output sample rate that corresponds to the sample rate of output DACs and corresponding analog low pass filters.

Digital baseband modulator adaptable to different modulation types

Varactor diodes having noncommensurate parametric values are utilized within respective cells of a nonlinear transmission line. By the appropriate selection of varactor cell parameters, the configuration of a nonlinear transmission line can be improved to alleviate problems associated with varactor turn-on and punch-through voltage limitations, soliton compression and inefficient use of varactor nonlinearity, reflections from mismatched load and source impedances, and rining and soliton generation.

Nonlinear transmission lines having noncommensurate varactor cells

A Monolithic Sampler is disclosed. The present invention overcomes the problem of inadequately low sampling rates that results from circuit designs or component limitations that constrain the bandwidths of previous instruments. The sampler includes five circuit stages: a local oscillator section that may be used to drive the system, a shock wave generator that produces high frequency edge-sharpened pulses, a reflection damping clamping section, a delay section, and a sampler section regulated by the stream of shock waves which produces an IF output. The local oscillator or a pulse generator (not shown) produces an input that propagates down a nonlinear transmission line. Once this input reaches the shock wave generator section, it encounters a series of hyperabrupt diodes which are employed as voltage dependent capacitors called varactors. These varactors deform the input pulses and generate a stream of spike-shaped waveforms known as shock waves. The shock waves successively energize sampling diodes in the sampling section of the circuit. When these diodes are energized, they open pathways from an RF input to sampling capacitors which charge up with small representative bits of current from the input. A sample or snapshot of the input is drawn from these capacitors through an IF output coupling network. The clamping and delay sections of the sampler minimize spurious ringing throughout the circuit and manage the timing of the oscillation of these reflections. The entire sampler is monolithically integrated on a single substrate using conventional semiconductor fabrication and packaging techniques.

Monolithic sampler

A pulse compressor consisting of a loaded transmission line having a pluraltiy of sections which have a ratio of dispersion to nonlinearity that decreases in the direction of pulse transmission.

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Santa Rosa, CA, United States of America

William J Anklam