| 摘要 |
Attenuation cell comprising first and second differential pairs of bipolar transistors. A gain control device applies a voltage VA-VB between the bases of both differential pairs and comprises a set of three diodes in which a current IA, a current IB and the sum IA+IB of both preceding currents flow, respectively. The two diodes seeing current IB and IA+IB generate a voltage, respectively VB and VC, and the difference between these two voltages is used to generate a value Iz used in a control loop. A desired value Vct is transformed into information Ix, then into information Iy proportional to absolute temperature T, and an error amplifier uses information Iy-Iz and generates currents IA and IB by minimizing this difference.
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