Amplifier device for amplifying small currents
AssigneeInficon GmbH
InventorNorbert Rolff
Life of this patent
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Abstract
An amplifier device for receiving currents, comprising a first current path for measuring smaller currents of less than 100 pA, an input amplifier device included in the first current path, having at least one first amplifier, an output, an inverting input, a first feedback path connecting the output to the inverting input, and a feedback element included in the first feedback path, wherein the first amplifier has at least one protective element, a second current path for measuring larger currents with a maximum current of at least 10 times the current to be received in the first current path, characterized in that at least one of the protective elements of the amplifier is part of the second current path.
Claims16
An amplifier device for receiving currents, comprising
- a first current path for measuring small currents of less than 100 pA,
- an input amplifier device (50) included in the first current path, comprising
- at least one first amplifier (1),
- an output,
- an inverting input (30),
- a first feedback path (41) connecting the output to the inverting input (30), and
- a feedback element (2) included in the first feedback path (41),
- wherein the first amplifier (1) has at least one protective element (18, 19, 20, 21),
- a second current path for measuring larger currents with a maximum current of at least 10 times the current to be received in the first current path,
- characterized in that,
- at least one of the protective elements (18, 19, 20, 21) of the input amplifier device (50) is part of the second current path.
The amplifier device according to any one of the preceding claims, characterized in that at least one of the protective elements (18, 19, 20, 21) is arranged between two inputs (30, 31) of the first amplifier (1) and connected thereto.
The amplifier device according to any one of the preceding claims, characterized in that the feedback element (2) in the first feedback path (41) is an electrical resistor.
The amplifier device according to any one of the preceding claims, characterized in that the feedback component (2) in the first feedback path (41) is a capacitor.
The amplifier device according to any one of the preceding claims, characterized in that the input amplifier device (50) comprises at least one further amplifier (3) forming a control loop with the first amplifier (1).
The amplifier device according to any one of the preceding claims, characterized in that at least one of the two supply connections (32, 33) of the first amplifier (1) is connected via an electrical resistor (6a, 6b) to the output of the first amplifier (1).
The amplifier device according to any one of the preceding claims, characterized in that the feedback path (41) connects the output of the last amplifier of the input amplifier device (50) consisting of the first amplifier (1) and the at least one further amplifier (3) to the inverting input (30) of the input amplifier device (50).
The amplifier device according to any one of the preceding claims, characterized in that the negative supply connection (33) of the first amplifier (1) is selectively connectible via a first switch (10) to a negative supply voltage (14) or ground, while the positive supply connection (32) of the first amplifier (1) is electrically conductively connected to the inverting connection (38) of a third amplifier (7), the non-inverting input (37) of which is selectively connectible via a second switch (11) to a positive supply voltage (15) or ground.
The amplifier device according to any one of the preceding claims, characterized in that the third amplifier (7) comprises a second feedback path (43) with an electrical resistor (8) and an electrical diode (9) arranged in parallel with the resistor (8) and conducting in the direction from the output (17) of said third amplifier to the positive supply connection (32) of the first amplifier (1) and blocking in the opposite direction.
The amplifier device according to any one of the preceding claims, characterized in that the first feedback path (41) is selectively connectible via a third switch (12) to a voltage which avoids or allows current flow in the feedback element (2) depending on the switch position.
The amplifier device according to any one of the preceding claims, characterized in that the ground references of the switches (10, 11) and the reference voltage (22) are changed by the forward voltage of the protective element (18).
The amplifier device according to any one of the preceding claims, characterized in that the second feedback path (43) comprises two diodes (9a, 9b) between which a resistor (39) leads with respect to the switch (11).
A gas detector comprising a mass spectrometric sensor or a total pressure sensor and an amplifier device according to any one of the preceding claims.
The method according to the preceding claim, characterized in that, for switching the current path, the non-inverting input of a third amplifier (7), whose inverting input is connected to the positive supply connection (32) of the first amplifier (1), is additionally connected to ground.
Dependencies are inferred from the claim text.