摘要 |
In a voltage clamp circuit, a normally-on type field-effect transistor having a negative threshold voltage has a drain connected to an input node, a source connected to an output node and grounded via a resistance element, and a gate supplied with an output voltage of a variable direct-current power supply. When a voltage at the output node becomes higher than a clamping voltage because of voltage drop of the resistance element, the field-effect transistor is tuned off. Accordingly, the output voltage is limited to be at most the clamping voltage. Thus, a response speed is higher than those of conventional voltage clamp circuits using diodes or the like.
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