THREE-AMPLIFIER GYRATOR

• US 3,643,183 A
• Filed: 05/19/1970
• Issued: 02/15/1972
• Est. Priority Date: 05/19/1970
• Status: Expired due to Term

• Current Assignee: Philip R. Geffe
• Original Assignee: Philip R. Geffe
• Inventors: Geffe, Philip R.
• Primary Examiner(s): Saalbach, Herman Karl
• Assistant Examiner(s): Gensler, Paul L.
• Application Number:
  US05/038,709
• Time in Patent Office: 637 Days
• Field of Search: 333/80,8T 330/12,85,139
• US Class Current: 333/215
• CPC Class Codes: H03H 11/42 Gyrators used in frequency selective networks H03H11/08

Abstract

Three identical inverting amplifiers are connected in a circuit combination of two amplifiers in cascade across the remaining amplifier. The circuit configuration, accomplishes wide banding in a gyrator.

Claims

1. A gyrator comprising, in combination:

first, second and third amplifiers with substantially the same single dominant pole and each being of the inverting type with high input and output impedance;

said second and third amplifiers being connected in cascade combination directly between input and output terminals of said first amplifier, said terminals also being the input and output terminals of the gyrator; and

a gain-controlling resistor connecting the common junction of said second and third amplifiers to a point of reference potential.

2. The combination of claim 1 wherein said first amplifier provides an inverting transconductance;

said second and third amplifiers connected in cascade providing a noninverting transconductance.

3. The combination of claim 2 wherein said gain-controlling resistor is selected to provide said transconductance of opposite sense to be directly proportional to the magnitude of said resistor.

4. The combination of claim 1 wherein said gaIn-controlling resistor is a positive valued resistor external to the circuit of the gyrator and being of a magnitude of 9/4 ohms or less connected in circuit combination with the resistive port of the input impedance for a unitized frequency to reduce the negative excursion of the resistance of the gyrator whereby stability is attained at all frequencies.