| 摘要 |
An apparatus for generating a substantially constant voltage control signal using either one of a voltage reference source and a current reference source includes a transistor device responsive to a supply voltage and the voltage control signal to produce a controlled current, an operational amplifier device for generating the voltage control signal in response to the voltage reference source, and a switching device for generating the voltage control signal in response to the current reference source. When the switching device is in one state thereof, an output signal of the operational amplifier device is connected through the transistor device in a closed loop back to an input terminal of the operational amplifier device. When the switching device is in another state thereof, the output signal of the operational amplifier device is connected directly in the closed loop back to an input terminal of the operational amplifier device. In particular, the switching device may be a single-pole, single-throw switch realized using either a pass gate device or a bonding wire option Circuit complexity is therefore reduced.
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