| 摘要 |
<p>PURPOSE:To check influences of of parasitic effects at every ship, by providing a parasitic effect detecting circuit which is independent from an internal circuit to an electrode for fetching the signal of the internal circuit. CONSTITUTION:A voltage which is higher than a level, at which a diode D3 can be broken down, is applied across a pad P3 and a trigger current is made to flow from a pad P1. If the relation between the betanpn of an npn transistor Q61 and the betapnp of a pnp transistor Q62 satisfies betanpn X betapnp>1 when the trigger current is made to flow, an electric current is made to flow from the pad P3 to another pad P2. Since the transistors Q61 and Q62 respectively have the same structures as an unwritten storage cell and written storage cell have, the value of the (betanpn mu betapnp) is the same as that of an actual storage cell. Therefore, whether or not faulty writing caused by a parasitic thyristor effect occurs can be checked through the electric current flowing from the pad P3 to the pad P2 and, moreover, this inspection can be performed on all chips.</p> |
