SUBSTRATE VOLTAGE GENERATING CIRCUIT

摘要

PURPOSE:To apply the operation margin test over a wide range by stopping the operation of a charge pump circuit only at wafer test. CONSTITUTION:A potential of a pad 8 is brought into a GND level at wafer test to turn of a FET 7. When a phi signal from an OSC 1 goes to a VCC level and a node N1 reaches an H level, the node N2 is charged instantly to a (VCC- VT) level and the node N1 is kept to the VCC level. When the phi signal goes to L, the node N1 goes to a GND level and no signal is transferred from the node N1 to a VBB level. The cycles above are repeated and no electron is injected at test.