Leland Stanford Junior University

Hrl Laboratories, LLC

University of California

New Focus, Inc.

Mark J Rodwell

David M Bloom

Robert A Marsland

Susan L Morton

Ken Elliott

Scott Thomas Allen

Robert A Marsland, Jr

Robert Sylvester Williamson, Iii

Shrinivasan Jaganathan

Disclosed is a time delay generatorapparatus and method. The apparatus includes a time delay gate, a mixer(a Gilbert cell circuit), and a current digital to analog converter. The mixer, comprised of first and second transistor differential pairsand, receives an analog input signalwithout a delay as well as a delayed input signalproduced by the time gate delay. The digital to analog converter regulates the relative current flow between a first control signaland a second control signal, effectively altering the mixing of the undelayed input signaland the delayed input signalto generate a delayed output signalwith a time or phase delay substantially equal to the temporal delay represented by the digital signal input. The time delay generator exhibits reduced phase noise and a linear time delay response.

Time delay apparatus and method of using same

Described embodiments provide a method and apparatus for transmission of optical communications. An embodiment provides an optical transmitter which includes a control circuit to enhance the stability of output power levels, a modulator circuit with precise impedance matching for high frequency performance, and an optical coupling mechanism that relaxes the alignment tolerances between the laser and the fiber and decreases the sensitivity of the gain medium to feedback from devices coupled to the fiber. These features allow the transmitter to deliver an optical output beam which can be modulated over a wide range of frequencies, duty cycles and amplitudes with very precise definition of the rising and falling edges of the waveform. In combination these features result in an optical transmitter that may be fabricated with relatively low cost and a reduced form factor when compared with prior art optical transmitters.

Method and apparatus for optical transmission

A microwave power amplifier is comprised of a plurality of series connected amplifier stages. Each stage is provided with a local negative feedback. The addition of the local voltage feedback distribution networks provide correct voltage distribution and equal current distribution for all transistors, such that the peak-to-peak voltage and current swings of each transistor can be set simultaneously to the values required for efficient amplifier operation. The method applies to both FETs and bipolar transistors. The series connected microwave power amplifier is thus characterized as a stack with local voltage feedback networks which provide an equal distribution of voltage across the transistors in the stack. The amplifier stages can be biased and tuned to collectively operate either as a class A or B amplifier.

Series-connected microwave power amplifiers with voltage feedback and

A high bandwidth RF sampler using equivalent time sampling comprising an RF coplanar waveguide integrated with sampling diodes on a gallium arsenide substrate. A monolithic, integrated coplanar strip nonlinear transmission line is integrated on the same substrate to receive sample pulses. These pulses are reshaped by the nonlinear transmission line to have a very fast edge. This edge is differentiated by a shunt inductance of a short circuit termination of a slot line portion of the RF signal coplanar waveguide. The resulting delta function sample pulses cause the sample diodes and integrated capacitors to develop an intermediate output frequency which is a replica of the RF signal at a lower frequency and no voltage conversion loss. RF signals of up to 300 Ghz can be sampled using this circuit.

Gallium arsenide monolithically integrated sampling head using

A high bandwidth RF sampler using equivalent time sampling comprising an RF coplanar waveguide integrated with sampling diodes on a gallium arsenide substrate. A monolithic, integrated nonlinear transmission line is integrated on the same substrate to receive sample pulses. These pulses are reshaped by the nonlinear transmission line to have a very fast edge. This edge is differentiated by a shunt inductance of a short circuit termination of a slot line portion of the RF signal coplanar waveguide. The resulting delta function sample pulses cause the sample diodes and integrated capacitors to develop an intermediate output frequency which is a replica of the RF signal at a lower frequency and no voltage conversion loss. RF signals of up to 300 Ghz can be sampled using this circuit.

An integrated coplanar strip nonlinear transmission line comprising a substrate of gallium arsenide upon which a heavily doped buried layer and a lightly doped surface layer of epitaxially grown gallium arsenide are grown. Two parallel conductors are integ

Integrated coplanar strip nonlinear transmission line

There is disclosed herein a non linear transmission line comprised of a 50 ohm coplanar monolithic waveguide formed on top of a gallium arsenide substrate having a layer of lightly doped epitaxial gallium arsenide with a heavily doped buried layer, said epitaxial layer having spaced, electrically isolated islands. A self aligned Schottky diode junction is formed at the intersection of each isolation island with the center conductor of the transmission line. The second conductor of the transmission line is coupled through a contact window and an ohmic contact to the buried layer in each isolation island.

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Palo Alto, CA, United States of America

Mark J Rodwell