Differential current amplifier
AssigneeThomson-CSF
InventorFrederic Lemaire
Life of this patent
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Abstract
The invention relates to differential current amplifiers. In order to obtain amplification of a difference between two currents I1 and I2 with good common mode rejection, the currents I1 and I2 are caused to pass alternately through two equal resistors R1 and R2 and the differential voltage drop across R1 and across R2 is amplified by a voltage amplifier.
Claims4
In a differential current amplifier having two inputs each receiving a respective input current I1 and I2, so as to produce at the output a signal proportional to the difference of the input currents, comprising a differential voltage amplifer having two inputs, two resistors connected to the same circuit node and having substantially the same value, periodic switching means are provided, actuated with a cyclic ratio close to 0.5 for
- (1) during a first half of each cycle, connecting the resistors to the inputs of the differential current amplifier so as to produce across the first resistor R1 a voltage drop varying as R1I1 and across the second resistor R2 a voltage drop varying as R2I2, and connecting the first resistor R1 to a first input of the differential voltage amplifier and the second resistor to a second input of the differential voltage amplifier,
- (2) during a second half of each cycle reversing the connections between the resistors and the inputs of the differential current amplifier so as to produce across the first resistor R1 a voltage drop varying as R1I2 and across the second resistor R2 a voltage drop varying as R2I1, and also reversing the connections between the resistors and the inputs of the differential voltage amplifier.
Dependencies are inferred from the claim text.