US 4,395,599 AGranted

Driving point impedance derived from a transfer impedance

AssigneeBell Telephone Laboratories, Incorporated

InventorHarold Seidel

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Abstract

Circuitry for converting a transfer function characteristic into a specified driving point impedance using feedforward techniques comprises: a directional coupler (90) having input, transmission and reflection ports; and unidirectional signal transfer means including transfer network (91) and amplifier (92) connected in cascade between the transmission and reflection ports. The impedance level of the transfer network is adjustable and is compensated for by the amplifier. A high impedance level allows for small element values for certain components such as capacitors so that a wide frequency band driving point impedance may be realized with integrated circuits. Further decrease in capacitor values is achieved utilizing capacitor magnification. The driving point impedance may be realized in balanced or unbalanced-to-ground fashion.

Claims11

Dependent claims

Circuitry including a directional coupler (90) comprising

two active members (120,121) each having an emitting element, a control element and a collecting element, and
first, second and third two-port networks (130-132) connected, respectively, between said emitting element, said control element and said collecting element of said members, said networks arranged so that the symmetric mode transfer gain and the antisymmetric mode transfer gain measured between said control elements and said collecting elements, are equal,
CHARACTERIZED BY
circuit means (91,92,102), external to said coupler, comprising a transfer signal circuit (91,92) having a transfer ratio of -.beta. for coupling said collecting element of one of said members to said control element of the other of said members, and
impedance networks, each designated Z.sub.R, terminating each said collecting element and each said control element,
said circuitry providing a driving point impedance between said collecting element of said other of said members and the circuitry reference point in the form Z.sub.in =(1+.beta.)Z.sub.R /(1-.beta.) whenever .beta.=(Z.sub.in -Z.sub.R)/(Z.sub.in +Z.sub.R).

3 more elements

Circuitry comprising a first directional coupler (90) and a second directional coupler (390), said first coupler having an input port (111), a transmission port (113) and a reflection port (112), said second coupler having an input port (411), a transmission port (413) and a reflection port (412), each said coupler including

two active members (e.g., 120,121) each having an emitting element, a control element and a collecting element, and
first, second and third two-port networks (e.g., 130-132) connected, respectively, between said emitting element, said control element and said collecting element of said members, said networks arranged so that the symmetric mode transfer gain and the antisymmetric mode transfer gain, measured between said control elements and said collecting elements, are equal, said circuitry further
CHARACTERIZED BY
unbalanced-to-balanced unity gain coupling means (400), the positive output of said coupling means being connected to said reflection port of said first coupler and the negative output of said coupling means being connected to said reflection port of said second coupler, and
circuit means (91,92), external to said first coupler and said second coupler comprising a transfer signal circuit (91,92) having a transfer ratio of -.beta., for connecting said transmission port of said first coupler to the input of said coupling means to provide a preselected, balanced driving point impedance across said input port of said first coupler and said input port of said second coupler.

2 more elements

Dependencies are inferred from the claim text.