| 摘要 |
The circuit includes means for limiting the potential difference that can exist between corresponding electrodes of two input transistors interconnected to form a differential amplifier stage. The control electrode of each input transistor is coupled via a normally conducting gating transistor to its respective input terminal and via a normally non-conducting clamping transistor to a common point to which is connected one end (source or emitter) of the main conduction paths of the two input transistors. In response to an input signal at an input terminal having a polarity and a first value to turn off an input transistor, the gating transistor is turned off and decouples the control electrode of the input transistor from its corresponding input terminal. Then, as the input signal increases beyond the first value in a direction to further reverse bias the input transistor, the clamping transistor is turned on and clamps the control electrode of the input transistor to the common point. The circuit may also include means connected to the output (drain or collector) electrodes of the two input transistor to prevent excessive voltage differentials between their output electrodes.
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