US 2008/0303556 A1 · POWER SUPPLY GROUND CROSSING DETECTION CIRCUIT

Abstract

A detecting circuit for detecting an input signal crossing a ground level is disclosed. The circuit comprises two PMOS transistors and two NMOS transistors connected, respectively. The PMOS transistors have source terminals connected to a power voltage, the gate terminals connected together and the drain terminal of the second PMOS transistors. The first NMOS transistor has the source terminal as an input terminal to retrieve an input signal, and the drain terminal to be act as output terminal and the second NMOS transistor has the source terminal grounded. The gate terminals of the two NMOS transistors are connected together and to a biased voltage. The circuit can also be used to detect the power voltage if the input terminal is set at the source terminal of the first PMOS transistor and the source terminal of the first NMOS transistor grounded.

Claims7

Dependent claims

A detecting circuit for detecting an input signal crossing a specified voltage, comprising:

a first PMOS transistor, a second PMOS transistor, a first NMOS transistor, and a second NMOS transistor, wherein both of said first PMOS transistor and second PMOS transistor have their gate terminals connected to both of drain terminals of said second PMOS transistor and second NMOS transistor, and said first NMOS transistor and said second NMOS transistor have their gate terminals connected to a BIAS voltage, and a source terminal of said second NMOS transistor is grounded and a source terminal of said second PMOS transistor is connected to a power voltage, and both of drain terminals of said first PMOS transistor and first NMOS transistor are connected and acted as an output terminal;
and
when said specified voltage is a ground level, then a source terminal of said first NMOS transistor is connected to said input signal and a source terminal of said first PMOS transistor is connected to said power voltage;
when said specified voltage is said power voltage, then said source terminal of said first NMOS transistor is grounded and a source terminal of said first PMOS transistor is connected to said input signal.

1 more element

Dependencies are inferred from the claim text.

Power supply ground crossing detection circuit

Life of this patent

Power supply ground crossing detection circuit

Life of this patent

Abstract

Claims7