A method of varying the gain of an amplifier and an amplifier array are provided. The amplifier array includes two or more amplifier stages ( 201, 202 ) connected in parallel with each amplifier stage having a gain control means. Input signal means ( 203, 204 ) are provided for each amplifier stage with the input signals of the amplifier stages being of different amplitude. Means for enabling and disabling an amplifier stage ( 216 ) are provided and means for summing the outputs of the enabled amplifier stages obtain an output signal ( 212 ). The gain of the amplifier array has a range from a low gain setting with a first amplifier stage ( 202 ) enabled, through increasing gain settings as the gain of the first amplifier stage is increased from a minimum to a maximum gain, a second amplifier stage ( 201 ) can then be enabled in addition to the first amplifier stage and the gain of the second amplifier stage increased from a minimum to a maximum gain, further amplifier stages are enabled as available up to a maximum gain setting for the amplifier array. Each amplifier stage that is enabled has a decreasingly attenuated input signal and a final amplifier stage to be enabled has a full input signal ( 203 ).

Variable gain amplifier

A high-speed serrodyne digital frequency translator utilizes a digital phase-shifter, for example, of series coupled Schiffman type cells, which have reference and delay paths which are switched by three-terminal devices of the gallium arsenide FET type. No bias voltages are used and the FETS are driven by the output of a binary divider network which in turn is composed of GaAs FETS as active elements. Thus switching in the picosecond range results.

High speed serrodyne digital frequency translator

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 phase shifter comprises a coarse phase tuning arrangement and a fine phase tuning arrangement. The coarse phase tuning arrangement provides a discrete number of phase shifts. The fine phase tuning arrangement includes a RLC network, having a resistor, an inductor and a capacitor. The fine phase tuning arrangement also comprises an optical arrangement for varying the resistance value of the resistor. This phase shifter is able to obtain broadband, continuous 360° phase shifting also at Gigahertz frequencies. It also allows close to linear phase shift versus frequency resulting in true time delay capability, very low insertion loss and high value of maximum phase adjust.

Continuously tunable MEMs-based phase shifter

A phase shift circuit used in a regenerating repeater, includes a separating unit for separating an input signal into two separate signals having a phase difference of a phase angle of 90° therebetween, one separated signal having a "0" phase and the other separated signal having a "π/2" phase. A distributing unit distributes the "0" phase separated signal and "π/2" phase separated signal as three distributed signals having phase difference of phase angles of 90° and 180° therebetween, one distributed signal having a "0" phase and the others being a "π/2" phase distributed signal and a "π" phase distributed signal. A weighting/compounding unit analyzes the "0" phase distributed signal, "π/2" phase distributed signal, and "π" phase distributed signal regarding a plurality of phase signals each having a phase shift extent, compounds each of the phase signals after being weighted by each amplitude, the weighting being performed by a weight control signal applied from an external stage, and generates an output signal adding a phase shift proportional to the weight to the input signal.

Phase shift circuit

An adjustable phase shifter for adjustably providing a 360° range of phase shift to RF signals by dividing the RF signals into three equal parts, adjusting the relative amplitudes of the parts of the RF signals and combining the three parts of the RF signals at relative phase angles of 0°, 120° and 240°.

Erwin F. Belohoubek

Papers

Adjustable phase shifter