Hybrid integrated impedance converter circuit
AssigneesHitachi, Ltd., Hitachi Denshi Kabushiki Kaisha
InventorToshiro Suzuki
Life of this patent
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Abstract
A hybrid integrated impedance converter circuit comprising a frequency dependent negative resistance circuit, in which two operational amplifiers are included. Each of the two operational amplifiers has an output terminal and an inverting input terminal, with a negative feedback capacitor being connected between these terminals. The negative feedback capacitor is formed by a stray capacitance which arises between conductors connected to the output and inverting input terminals, which conductors are placed in close proximity to each other.
Claims14
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.
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.
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.
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.
Dependencies are inferred from the claim text.