Circuits using transistors to provide variable phase shift

Claim 2

Apparatus for providing a variable phase shift, for an AC signal, comprising, a. first and second transistors having base, collector and emitter electrodes, having the collector electrode of said first coupled to the collector electrode of said second transistor, b. a first two terminal reactive network having one terminal coupled to the emitter electrode of said first transistor, c. a second two terminal reactive network having one terminal coupled to the emitter electrode of said second transistor, d. first means coupled to said other terminals of said first and second reactive networks for providing a ground return path for said emitter electrodes of said first and second transistors, e. second means coupled to said base electrodes of said first and second transistors for applying to said base electrodes said AC signal, and f. third means for varying the current through one of said transistors relative to the other to vary the effective complex impedance at said collector electrodes due to said first and second reactive networks and said first and second transistor impedances, for varying the phase shift of said AC signal.

Claim 3

The apparatus according to claim 1 wherein said first reactive network comprises, a. a first resistor coupled between the emitter electrode of said first transistor and said first means, and b. a capacitor in shunt with said resistor.

Claim 4

The apparatus according to claim 1 wherein said second reactive network comprises, a. a second resistor coupled between the emitter electrode of said second transistor and said first means, and b. an inductor in shunt with said resistor.

Claim 5

The apparatus according to claim 2 wherein said resistor and capacitor are selected to provide a phase angle having an absolute magnitude of relatively 60* at the frequency of said signal.

Claim 6

The apparatus according to claim 1 wherein, said first and second reactive networks are selected to provide a phase angle at said frequency of substantially the same absolute magnitude but of opposite polarity.

Claim 7

Apparatus to provide a variable phase shift with a constant amplitude for a AC signal comprising, a. first and second active devices each having input, output and common terminals, and each having an internal impedance between said common and output terminals which is dependent upon a current flowing therethrough, a coupling path between said common terminal of said first device and said common terminal of said second device, b. first and second reactive networks coupled in series between said output terminals of said first and second devices each network selected to provide a given phase shift at the frequency of said AC signal, c. means coupled between the junction of said first and second reactive networks and a point of reference potential to provide a return path for currents flowing through said first and second active devices, d. means coupled to the input terminals of said first and second active devices for applying said AC signal thereto, and, e. means coupled to one of said input terminals for varying the conduction of said devices in mutually opposing directions and therefore said internal impedance to cause a phase shift to be provided to said AC signal at said common terminal in accordance with said impedance variation and said given phase shift of said reactive networks, said impedance variation being in a direction to cancel any variation in amplitude of said AC signal at said common terminal due to the action of said reactive networks.

Claim 8

Apparatus to provide a variable phase shift with a constant amplitude for a AC signal comprising, a. first and second active devices each having input, output and common terminals, and each having an internal impedance between said common and output terminals which is dependent upon a current flowing therethrough, a coupling path between said common terminal of said first device and said common terminal of said second device, b. first and second reactive networks coupled in series between said output terminals of said first and second devices each network selected to provide a given phase shift at the frequency of said AC signal, c. means coupled between the junction of said first and second reactive networks and a point of reference potential to provide a return path for currents flowing through said first and second active devices, d. means coupled to the input terminals of said first and second active devices for applying said AC signal thereto, and, e. means coupled to one of said input terminals for varying the conduction of said devices in mutually opposing directions and therefore said internal impedance to cause a phase shift to be provided to said AC signal at said common terminal in accordance with said impedance variation and said given phase shift of said reactive networks, said impedance variation being in a direction to cancel any variation in amplitude of said AC signal at said common terminal due to the action of said reactive networks.

Claim 9

The apparatus according to claim 6 wheRein said first and second active devices are transistors, said common terminals being the collector electrodes thereof, said output terminals being the emitter electrodes thereof, and said input terminals being the base electrodes thereof.

Claim 10

Apparatus for providing a variable phase shift for predetermined AC signals, comprising, a. first and second active devices having input, output and common terminals, having said common terminals coupled one to another, b. first and second reactive networks coupled in series between said output terminals of said first and second devices, said first reactive network selected to provide a phase shift of a given magnitude and polarity, said second reactive network selected to provide a phase shift substantially equal to said given magnitude but of an opposite polarity, c. means coupled between said first and second reactive networks and a point of reference potential for providing a ground return path for current flowing through said first and second devices, d. means coupled to said input terminals of said first and second devices for applying said AC signal thereto, and e. means coupled to one of said input terminals of said first and second devices for varying the conduction of said first and second devices to cause a phase shift of said AC signal at said common terminal in accordance with said conduction variation and between a first phase angle determined substantially only by said conduction of said first device and said first reactive network and a second phase angle determined substantially only by said conduction of said second device and said second reactive network.

Claim 11

Apparatus for providing a variable phase shift for predetermined AC signals, comprising, a. first and second active devices having input, output and common terminals, having said common terminals coupled one to another, b. first and second reactive networks coupled in series between said output terminals of said first and second devices, said first reactive network selected to provide a phase shift of a given magnitude and polarity, said second reactive network selected to provide a phase shift substantially equal to said given magnitude but of an opposite polarity, c. means coupled between said first and second reactive networks and a point of reference potential for providing a ground return path for current flowing through said first and second devices, d. means coupled to said input terminals of said first and second devices for applying said AC signal thereto, and e. means coupled to one of said input terminals of said first and second devices for varying the conduction of said first and second devices to cause a phase shift of said AC signal at said common terminal in accordance with said conduction variation and between a first phase angle determined substantially only by said conduction of said first device and said first reactive network and a second phase angle determined substantially only by said conduction of said second device and said second reactive network.