Capacitance circuit

Claim 2

A capacitance circuit comprising a pn-junction capacitance element having a breakdown characteristic and which generates noise signal components at breakdown, and a pn-junction Zener diode whose breakdown voltage is lower than that of said pn-junction capacitance element and whose noise characteristic is preferable to that of said pn-junction capacitance element, said pn-junction capacitance element and said pn-junction Zener diode being connected in parallel with each other, and wherein said pn-junction Zener diode forms a by-pass for the noise signal components which are generated from said pn-junction capacitance element by breakdown thereof, wherein said capacitance circuit is fabricated as a semiconductor integrated circuit.

Claim 3

A transistor circuit comprising a transistor having base, emitter and collector electrodes, a resistor connected between said collector electrode and a bias voltage source, a circuit means connected between said emitter electrode and ground, a filter circuit connected between said collector electrode and ground including a pn-junction capacitor and a pn-junction Zener diode connected in parallel, said pn-junction Zener diode having a breakdown voltage which is lower than the breakdown voltage of said pn-junction capacitor and noise characteristics which are preferable to those of said pn-junction capacitor, both the pn-junctions of said pn-junction capacitor and said pn-junction Zener diode being reverse-biased at a voltage below the breakdown voltage of said pn-junction Zener diode, and means for supplying an A.C. signal to the base electrode of said transistor, wherein said pn-junction Zener diode forms a by-pass for the noise signal components which are generated from said pn-junction capacitor when the voltage of said A.C. signal appearing at said collector electrode added to said voltage reverse-biasing said pn-junctions attains a voltage value higher than the breakdown voltage of said pn-junction capacitor.

Claim 4

A transistor circuit comprising a transistor having base, emitter and collector electrodes, a resistor connected between said collector electrode and a bias voltage source, a circuit means connected between said emitter electrode and ground, a filter circuit connected between said collector electrode and ground including a pn-junction capacitor and a pn-junction Zener diode connected in parallel, said pn-junction Zener diode having a breakdown voltage which is lower than the breakdown voltage of said pn-junction capacitor and noise characteristics which are preferable to those of said pn-junction capacitor, both the pn-junctions of said pn-junction capacitor and said pn-junction Zener diode being reverse-biased at a voltage below the breakdown voltage of said pn-junction Zener diode, and means for supplying an A.C. signal to the base electrode of said transistor, wherein said pn-junction Zener diode forms a by-pass for the noise signal components which are generated from said pn-junction capacitor when the voltage of said A.C. signal appearing at said collector electrode added to said voltage reverse-biasing said pn-junctions attains a voltage value higher than the breakdown voltage of said pn-junction capacitor.

Claim 5

A transistor circuit as defined in claim 2, wherein said pn-junction Zener diode is formed by the base-emitter junction of a further transistor.

Claim 6

The combination according to claim 2, wherein said transistor circuit is fabricated as a semiconductor integrated circuit.

Claim 7

In a transistor detector circuit comprising a detecting transistor having base, emitter and collector electrodes, a resistor connected between said collector electrode and a bias voltage source, a time constant circuit connected between said emitter electrode and ground, a filter circuit connected between said collector electrode and ground, an input terminal connected to said base electrode for supplying an input signal to be detected, and an output terminal connected to said emitter electrode for deriving an output signal, the improvement wherein said filter circuit includes a pn-junction capacitor and a pn-junction Zener diode connected in parallel, said pn-junction Zener diode having a breakdown voltage which is lower than the breakdown voltage of said pn-junction capacitor and noise characteristics which are preferable to those of said pn-junction capacitor, both the pn-junctions of said pn-junction capacitor and said pn-junction Zener diode being reverse-biased at a voltage below the breakdown voltage of said pn-junction Zener diode, and said pn-junction Zener diode forms a by-pass for the noise signal components which are generated from said pn-junction capacitor when the voltage of said input signal appearing at said collector electrode added to said voltage reverse-biasing said pn-junctions attains a voltage value higher than the breakdown voltage of said pn-junction capacitor.

Claim 8

In a transistor detector circuit comprising a detecting transistor having base, emitter and collector electrodes, a resistor connected between said collector electrode and a bias voltage source, a time constant circuit connected between said emitter electrode and ground, a filter circuit connected between said collector electrode and ground, an input terminal connected to said base electrode for supplying an input signal to be detected, and an output terminal connected to said emitter electrode for deriving an output signal, the improvement wherein said filter circuit includes a pn-junction capacitor and a pn-junction Zener diode connected in parallel, said pn-junction Zener diode having a breakdown voltage which is lower than the breakdown voltage of said pn-junction capacitor and noise characteristics which are preferable to those of said pn-junction capacitor, both the pn-junctions of said pn-junction capacitor and said pn-junction Zener diode being reverse-biased at a voltage below the breakdown voltage of said pn-junction Zener diode, and said pn-junction Zener diode forms a by-pass for the noise signal components which are generated from said pn-junction capacitor when the voltage of said input signal appearing at said collector electrode added to said voltage reverse-biasing said pn-junctions attains a voltage value higher than the breakdown voltage of said pn-junction capacitor.

Claim 9

A capacitance circuit comprising a pn-junction capacitance element having a breakdown characteristic and which generates noise signal components at breakdown, a pn-junction Zener diode connected in parallel with said pn-junction capacitance element, said pn-junction Zener diode having a breakdown voltage lower than that of said pn-junction capacitance element and having noise characteristics preferable to that of said pn-junction capacitance element, bias means for reverse-biasing both the pn-junctions of said pn-junction capacitance element and said pn-junction Zener diode at a voltage lower than the breakdown voltage of said pn-junction Zener diode, and means for supplying an A. C. signal across said pn-junction capacitance element and said pn-junction Zener diode, wherein said pn-junction Zener diode forms a by-pass for the noise signal components which are generated from said pn-junction capacitance element when the voltage of said A. C. signal applied to said pn-junction capacitance element added to the voltage of said bias means applied thereto attains a voltage value higher than the breakdown voltage of said pn-junction capacitance element.

Claim 10

A capacitance circuit comprising a pn-junction capacitance element having a breakdown characteristic and which generates noise signal components at breakdown, a pn-junction Zener diode connected in parallel with said pn-junction capacitance element, said pn-junction Zener diode having a breakdown voltage lower than that of said pn-junction capacitance element and having noise characteristics preferable to that of said pn-junction capacitance element, bias means for reverse-biasing both the pn-junctions of said pn-junction capacitance element and said pn-junction Zener diode at a voltage lower than the breakdown voltage of said pn-junction Zener diode, and means for supplying an A. C. signal across said pn-junction capacitance element and said pn-junction Zener diode, wherein said pn-junction Zener diode forms a by-pass for the noise signal components which are generated from said pn-junction capacitance element when the voltage of said A. C. signal applied to said pn-junction capacitance element added to the voltage of said bias means applied thereto attains a voltage value higher than the breakdown voltage of said pn-junction capacitance element.

Claim 11

In a detector circuit comprising: an input terminal to which an input signal is applied; a bias terminal to which a bias voltage is applied; an output terminal; a detector element connected between said input and output terminals and being coupled to said bias terminal and a filter circuit connected to said detector element for preventing high frequency signals from being coupled to said bias terminal, said filter circuit including a pn-junction capacitor having a prescribed breakdown characteristic and which generates noise signal components at breakdown; the improvement wherein said filter circuit further includes means, connected in parallel with said pn-junction capacitor, for by-passing noise signal components generated at the pn-junction of said capacitor, said means comprising a pn-junction Zener diode having a breakdown voltage lower than that of said pn-junction capacitor.

Claim 12

In a detector circuit comprising: an input terminal to which an input signal is applied; a bias terminal to which a bias voltage is applied; an output terminal; a detector element connected between said input and output terminals and being coupled to said bias terminal and a filter circuit connected to said detector element for preventing high frequency signals from being coupled to said bias terminal, said filter circuit including a pn-junction capacitor having a prescribed breakdown characteristic and which generates noise signal components at breakdown; the improvement wherein said filter circuit further includes means, connected in parallel with said pn-junction capacitor, for by-passing noise signal components generated at the pn-junction of said capacitor, said means comprising a pn-junction Zener diode having a breakdown voltage lower than that of said pn-junction capacitor.

Claim 13

The improvement according to claim 7, wherein said detector element comprises a transistor, the base of which is connected to said input terminal, the emitter of which is connected to said output terminal, and the collector of which is coupled to said bias terminal, said pn-junction Zener diode by-passing noise signal components which are generated by said pn-junction capacitor, upon the voltage value of the signal which appears at the collector of said transistor, added to the voltage from said bias terminal reverse-biasing the pn-junctions of said capacitor and Zener diode, exceeding the breakdown voltage of said pn-junction capacitor.