Space Systems/loral, LLC

Precision Microwave Inc.

Ming L Yung

Bernard M Albrecht, Jr

Nicholas L Muhlhauser

Andrew M Kennedy, Ii

Elizabeth C Townley

Stephen T Herbusky

An improved accuracy phase shifter having cascaded phase shifting modules is provided for phase shifting a pulse train which rather than utilizing two pairs of control voltage leads for each phase shifting module, utilizes only one pair to significantly reduce the electromagnetic interference between the cascaded phase shifting modules. The result is that the phase of an incoming pulse train can be shifted from 0 to 360&deg; in 3&deg; increments with &plus;/&minus;1&deg; accuracy. When the subject phase shifter is utilized in long haul fiber-optic cable networks operating at 10 gigabits/sec. for correcting phase offsets of data streams transmitted over ultra long distances, the utilization of the subject phase shifter plays a part in obviating the necessity of having regeneration units every 70 to 100 miles, thus permitting error-free transmission over as many as 2500 miles without the requirement for regeneration.

Method and apparatus for improving the accuracy of a phase shifter

A multifunction microwave modulator circuit has an input signal splitter to provide two equal amplitude signal components. A phase quadrature relationship between the two signal components is obtained by constructing the splitter as a Lange coupler. There is pair of circuit cells, each of which operates separately on one of the two signal components to electronically adjust a vector representation of the signal to provide a vector having a desired amplitude, ranging over both positive and negative values of amplitude, including zero amplitude. The signal vectors of the two cells are combined by means of a Wilkinson combiner to provide an output signal represented by a resultant vector which may have any direction within 360 degrees, and an amplitude scale factor which varies from unity to zero. Each circuit cell has a Lange coupler with output terminals terminated with an impedance, such as back-biased transistors, variable in response to a control voltage to reflect power via a second input terminal to the Wilkinson combiner. The circuit may be operated in reciprocal fashion by applying an input microwave signal to the Wilkinson combiner and extracting the output signal from the Lange coupler of the power splitter.

Microwave modulator having adjustable couplers

A variable electronically controlled phase shift circuit including a phase splitter stage including a 90 degree phase divider to split an RF input signal into 0 and 90 degree components. Each split signal is further split into two pairs that are displaced in phase by 180 degrees to provide, 0 degree, 180 degree and degree, 270 degree pairs. Four signals of the signal pairs are applied to a phase controller subcircuit wherein one of each of the two signal pairs may be attenuated by a control signal. The signal pairs from the phase controller sub-circuit are then summed and the summed pairs are combined into a single output signal. The phase of the output signal is controlled by varying the relative amplitudes of at least one of the component signals of the 0 degree, 180 degree and 90 degree, 270 degree pairs by means of the control signals on the phase control sub-circuit.

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Los Altos, CA, United States of America

Ming L Yung