Patent ID: 7414454

Claim:
A voltage switching circuit comprising: a first circuit having a first node, the first circuit outputting a first voltage from the first node; a second circuit having a second node, the second circuit outputting a second voltage from the second node; and a third circuit connected between the first and second nodes, and including a first transistor and a second transistor which are connected in series, the first transistor being connected to the first node and the second transistor being connected to the second node, wherein both the first and the second transistors are depletion-type transistors, and the first transistor is cutoff when the second circuit outputs the second voltage at a voltage level which is higher than a voltage level of a power supply voltage, wherein a voltage level of a gate of the first transistor is substantially equal to a voltage level of a gate of the second transistor when the second circuit outputs the second voltage at the voltage level which is higher than the voltage level of the power supply voltage, wherein a source of the first transistor is connected to a drain of the second transistor, the first voltage is supplied to a drain of the first transistor when the first circuit outputs the first voltage, and the second voltage is supplied to a source of the second transistor when the second circuit outputs the second voltage.