Difference measurement circuit for a control device and scales with electromagnetic force compensation having such a control device, whereby the output of the difference measurement circuit is largely temperature independent

摘要

Differential measurement circuit (1) is suitable for generating an output signal proportional to the difference in two photo-currents (I1, I2) generated by two photo-diodes (D1, D2). At least one switch is connected between the diodes and node point and controlled by a control unit so that it is periodically switched between two states of equal length in which first one photo-current and then the other is applied to the node point, at which a charge difference is formed to generate an output signal. The invention also relates to a corresponding control device (10) with a difference measurement circuit (1) and weighing scales with electromagnetic force compensation and an inventive control device.