GYRATOR COMPRISING VOLTAGE-CONTROLLED DIFFERENTIAL CURRENT SOURCES

• US 3,758,885 A
• Filed: 10/05/1972
• Issued: 09/11/1973
• Est. Priority Date: 10/09/1971
• Status: Expired due to Term

• Current Assignee: Arnoldus Biesheuvel, Johannes Otto Voorman
• Original Assignee: Arnoldus Biesheuvel, Johannes Otto Voorman
• Inventors: Voorman, Johannes Otto, Biesheuvel, Arnoldus
• Primary Examiner(s): Gensler, Paul L.
• Application Number:
  US05/295,208
• Time in Patent Office: 341 Days
• Field of Search: 333/8R,8T 307/295
• US Class Current: 333/215
• CPC Class Codes: H03H 11/42 Gyrators used in frequency selective networks H03H11/08

Abstract

The application relates to a gyrator which includes two voltagecontrolled differential current sources. Two equivalent npntransistors are used in one current source and two equivalent npn-transistors are used in the other current source. In addition steps have been taken in the gyrator to greatly reduce the D.C. offset currents at the input and output terminals.

Claims

1. Gyrator which comprises a first and a second voltagecontrolled differential current source, which current sources each include two input transistors and have two outputs, the control electrodes of the input transistors of the first differential current source also forming the inputs of the gyrator, whilst the control electrodes of the input transistors of the second differential current source also form the outputs of the gyrator, each of the outputs of the first differential current source being connected to an output of the gyrator, whilst each of the outputs of the second differential current source is connected to an input of the gyrator, at least one of the two inputs and both outputs of the gyrator being connected via high-resistance current sources to points of constant potential whilst each of the input transistors has a first and a second main electrode, characterized in that, at least in the second differential current source, a high-resistance current source is connected in each of the circuits between the first main electrodes of the two input transistors and a supply point, whilst each of the first main electrodes is connected via a current feedback path to the control electrode of a first transistor the main current path of which is connected in the circuit between the second main electrode of an input transistor and another supply point, the two outputs of the differential current source each being connected via the main current path of at least one auxiliary transistor to the second main electrode of the respective input transistor the main current path of which also forms part of the said circuit between the second main electrode of the respective input transistor and another supply point, means being provided to couple all the said highresistance current sources to the same current adjusting element.

2. Gyrator as claimed in claim 1, characterized in that in the second differential current source the first main electrode of each of the input transistors is the collector and the second main electrode of the respective transistor is the emitter, the collector of each of the input transistors being connected via the emitter collector path of a second transistor to the base of the first transistor, which transistor also is the auxiliary transistor, the emitter of the first transistor, which emitter also forms an output of the second differential current source, being connected via the collector emitter path of a transistor to the respective high-resistance current Source, whilst the base of the latter transistor is connected via at least one semiconductor diode to the base of the first transistor, at least one semiconductor diode being connected in parallel with the collector emitter path of the latter transistor.

3. Gyrator as claimed in claim 1, characterized in that the emitters of the input transistors of the first differential current source are each connected via the series combination of the emitter collector path of the first auxiliary transistor and the collector base path of a second auxiliary transistor to the collector of the respective input transistor, the collectors of the first auxiliary transistors each being connected via the base emitter path of at least one third auxiliary transistor to the base of the respective first auxiliary transistor, whilst the collector of the third auxiliary transistor is connected to an output of the first differential current source.