Hybrid integrated impedance converter circuit

Claim 2

In an impedance converter circuit constructed of a hybrid integrated circuit comprising first, second, third, fourth and fifth impedance elements and first and second operational amplifiers between an input terminal and an earth terminal, said first to fifth impedance elements being connected in series between said input terminal and said earth terminal, an output terminal of said first operational amplifier being connected between said first impedance element and second impedance element, a non-inverting input terminal of said first operational amplifier being connected between said fourth impedance element and said fifth impedance element, an output terminal of said second operational amplifier being connected between said third impedance element and said fourth impedance, a non-inverting input terminal of said second operational amplifier being connected to said input terminal, inverting input terminals of said first and second operational amplifiers being connected between said second impedance element and said third impedance element, said converter circuit being susceptible to instability due to the occurrence of stray capacitances, the improvement which comprises a negative feedback capacitance disposed between the output terminal of at least one of said first and second operational amplifiers and the inverting input terminal thereof, said negative feedback capacitance being deliberately formed by stray capacitance between an interconnection spliced to the output terminal of said at least one of said first and second operational amplifiers and an interconnection spliced to the respective inverting input terminal thereof, said negative feedback capacitance being of a value to substantially stabilize operation of said converter circuit.

Claim 3

A hybrid integrated impedance converter circuit according to claim 1, wherein said negative feedback capacitances are formed between the respective output terminals of both of said first and second operational amplifiers and the respective inverting input terminals thereof.

Claim 4

A hybrid integrated impedance converter circuit according to claim 1, wherein a value of said negative feedback capacitance is set to be, at least, approximately equal to a maximum value of stray capacitances between interconnections spliced to said non-inverting and inverting input terminals of said operational amplifiers and a stray capacitance between the interconnection spliced to said inverting input terminals and the earth of said hybrid integrated circuit.

Claim 5

A hybrid integrated impedance converter circuit according to claim 1, wherein said negative feedback capacitance is formed by stray capacitance owing to a proximate arrangement of the interconnection spliced to the output terminal of said at least one of said first and second operational amplifiers and an interconnection spliced to the inverting input terminal thereof.

Claim 6

A hybrid integrated impedance converter circuit according to claim 1, wherein said negative feedback capacitance is formed by stray capacitance owing to a crossover arrangement of the interconnections spliced to the output terminal of said at least one of said first and second operational amplifiers and an interconnection spliced to the inverting input terminal thereof.

Claim 7

A hybrid integrated impedance converter circuit according to claim 5, wherein a width of those parts of said interconnections which are held in the crossover arrangement is greater than a width of the remaining parts.

Claim 8

A hybrid integrated impedance converter circuit according to claim 1, 2, 3, 4, 5, or 6, wherein said first and fifth impedance elements are capacitive elements, and said second, third and fourth impedance elements are resistive elements.

Claim 9

A hybrid integrated impedance converter circuit comprising: an input terminal and an earth terminal; impedance means providing a plurality of impedance elements connected in series between said terminals; a pair of operational amplifiers, each of which has an output terminal, an inverting input terminal and a non-inverting input terminal, said terminals being coupled to said impedance means through conductors, respectively; said converter circuit being susceptible to instability due to the occurrence of stray capacitances, and a negative feedback capacitor connected between said output and inverting input terminal of at least one of said amplifiers, said negative feedback capacitor being a stray capacitance deliberately formed between conductors connected to said output and inverting input terminals, said negative feedback capacitance being of a value to substantially stabilize operation of said converter circuit.

Claim 10

A hybrid integrated impedance converter circuit comprising: an input terminal and an earth terminal; impedance means providing a plurality of impedance elements connected in series between said terminals; a pair of operational amplifiers, each of which has an output terminal, an inverting input terminal and a non-inverting input terminal, said terminals being coupled to said impedance means through conductors, respectively; said converter circuit being susceptible to instability due to the occurrence of stray capacitances, and a negative feedback capacitor connected between said output and inverting input terminal of at least one of said amplifiers, said negative feedback capacitor being a stray capacitance deliberately formed between conductors connected to said output and inverting input terminals, said negative feedback capacitance being of a value to substantially stabilize operation of said converter circuit.

Claim 11

A hybrid integrated impedance converter circuit according to claim 8, wherein said negative feedback capacitor is a stray capacitance owing to a proximate arrangement of conductors connected to said output and inverting input terminals.

Claim 12

A hybrid integrated impedance converter circuit according to claim 8, wherein said negative feedback capacitor is a stray capacitance owing to a crossover arrangement of conductors connected to said output and inverting input terminals.

Claim 13

A hybrid integrated impedance converter circuit comprising: an input terminal and an earth terminal; impedance means providing a plurality of impedance elements connected in series between said terminals; and a pair of operational amplifiers, each of which has an output terminal, an inverting input terminal and a non-inverting input terminal, said terminals being coupled to said impedance means through conductors, respectively, said converter circuit being susceptible to instability due to the occurrence of stray capacitances, wherein the respective inverting input terminals are connected together by a conductor coupled between said inverting input terminals, said conductor being arranged in proximate relationship with conductors coupled to the respective output terminals of each of said amplifiers to form a negative feedback capacitor between said output and inverting input terminals of each said amplifier by stray capacitance deliberately formed between said conductors connected to said output terminals and said inverting input terminals, said negative feedback capacitance being of a value to substantially stabilize operation of said converter circuit.

Claim 14

A hybrid integrated impedance converter circuit comprising: an input terminal and an earth terminal; impedance means providing a plurality of impedance elements connected in series between said terminals; and a pair of operational amplifiers, each of which has an output terminal, an inverting input terminal and a non-inverting input terminal, said terminals being coupled to said impedance means through conductors, respectively, said converter circuit being susceptible to instability due to the occurrence of stray capacitances, wherein the respective inverting input terminals are connected together by a conductor coupled between said inverting input terminals, said conductor being arranged in proximate relationship with conductors coupled to the respective output terminals of each of said amplifiers to form a negative feedback capacitor between said output and inverting input terminals of each said amplifier by stray capacitance deliberately formed between said conductors connected to said output terminals and said inverting input terminals, said negative feedback capacitance being of a value to substantially stabilize operation of said converter circuit.

Claim 15

In an impedance converter circuit constructed of a hybrid integrated circuit comprising first, second, third, fourth and fifth impedance elements and first and second operational amplifiers between an input terminal and an earth terminal, said first to fifth impedance elements being connected in series between said input terminal and said earth terminal, an output terminal of said first operational amplifier being connected between said first impedance element and second impedance element, a non-inverting input terminal of said first operational amplifier being connected between said fourth impedance element and said fifth impedance element, an output terminal of said second operational amplifier being connected between said third impedance element and said fourth impedance, a non-inverting input terminal of said second operational amplifier being connected to said input terminal, inverting input terminals of said first and second operational amplifiers being connected between said second impedance element and said third impedance element, wherein the respective inverting input terminals are connected together by a conductor coupled between said inverting input terminals, said converter circuit being susceptible to instability due to the occurrence of stray capacitances, said conductor being arranged in proximate relationship with conductors coupled to the respective output terminals of each of said amplifiers to form negative feedback capacitances disposed between the respective output terminals of said first and second operational amplifiers and the respective inverting input terminals thereof by stray capacitances deliberately formed between said conductors coupled to the respective output terminals of said first and second operational amplifiers to the respective inverting input terminals thereof, said negative feedback capacitance being of a value to substantially stabilize operation of said converter circuit.

Claim 16

In an impedance converter circuit constructed of a hybrid integrated circuit comprising first, second, third, fourth and fifth impedance elements and first and second operational amplifiers between an input terminal and an earth terminal, said first to fifth impedance elements being connected in series between said input terminal and said earth terminal, an output terminal of said first operational amplifier being connected between said first impedance element and second impedance element, a non-inverting input terminal of said first operational amplifier being connected between said fourth impedance element and said fifth impedance element, an output terminal of said second operational amplifier being connected between said third impedance element and said fourth impedance, a non-inverting input terminal of said second operational amplifier being connected to said input terminal, inverting input terminals of said first and second operational amplifiers being connected between said second impedance element and said third impedance element, wherein the respective inverting input terminals are connected together by a conductor coupled between said inverting input terminals, said converter circuit being susceptible to instability due to the occurrence of stray capacitances, said conductor being arranged in proximate relationship with conductors coupled to the respective output terminals of each of said amplifiers to form negative feedback capacitances disposed between the respective output terminals of said first and second operational amplifiers and the respective inverting input terminals thereof by stray capacitances deliberately formed between said conductors coupled to the respective output terminals of said first and second operational amplifiers to the respective inverting input terminals thereof, said negative feedback capacitance being of a value to substantially stabilize operation of said converter circuit.

Claim 17

A hybrid integrated impedance converter circuit according to claim 11 or 12, wherein said negative feedback capacitor is a stray capacitance owing to a crossover arrangement of said conductors connected to said output terminals and inverting input terminals.

Claim 18

A hybrid integrated impedance converter circuit according to claim 11 or 12, wherein a value of said each negative feedback capacitance is set to be, at least, approximately equal to a maximum value of stray capacitances between interconnections spliced to said non-inverting and inverting input terminals of said operational amplifiers and a stray capacitance between the interconnection spliced to said inverting input terminals and the earth of said hybrid integrated circuit so that said negative feedback capacitance will offset the other stray capacitances to reduce the tendency of the circuit to oscillate.