1. Field of the Invention
The present invention relates to a power supply circuit for supplying a voltage and a testing device for testing an electronic device. More particularly, the present invention relates to a power supply circuit for supplying a constant voltage.
2. Description of Related Art
A conventional testing device for testing a semiconductor memory or the like uses a voltage generation circuit for supplying a constant voltage to the semiconductor memory as a power supply for driving the semiconductor memory, in order to prevent damage or the like of the semiconductor memory. As a device for supplying a constant voltage to a load, a voltage generation circuit disclosed in Japanese Patent Application Laying-Open No. 7-333249 is presently known, for example. This voltage generation circuit increases and reduces a current drawn from a supply line for supplying the voltage to the load based on increase and decrease of a current flowing through the supply line.
In order to achieve a high-speed operation of the conventional constant voltage generation circuit, however, an analog circuit such as a high-performance subtracter circuit is required. Moreover, there was a disadvantage that the circuit scale became larger, for example. In addition, the operation was delayed in some cases, because the current was controlled after the current actually had started to flow through a resistor.