Wave shaping circuit having a maximum voltage detector and a minimum voltage detector

Claim 2

A Schmitt trigger circuit comprising: maximum voltage detecting means for detecting and retaining a maximum voltage of an input signal; minimum voltage detecting means for detecting and retaining a minimum voltage of said input signal; threshold voltage generating means for receiving said detected maximum and minimum voltages and generating a high-level threshold voltage and a low-level threshold voltage; first voltage comparing means for comparing a voltage of said input signal with said high-level threshold voltage; second voltage comparing means for comparing a voltage of said input signal with said low-level threshold voltage; and a flip-flop circuit controlled by outputs from said first and second voltage comparing means to produce a predetermined output signal.

Claim 3

The Schmitt trigger circuit according to claim 1, wherein said threshold voltage generating means includes resistor means.

Claim 4

The Schmitt trigger circuit according to claim 1, wherein said maximum voltage detecting means comprises: a reference voltage source connected to an input node receiving said input signal; a power source; a bipolar transistor having a base connected to said input node receiving said input signal and to said reference voltage source, and a collector connected to said power source; a constant current source connected between an emitter of said bipolar transistor and a circuit ground; and a capacitor connected between the emitter of the bipolar transistor and a circuit ground.

Claim 5

The Schmitt trigger circuit according to claim 1, wherein said maximum voltage detecting means comprises: a reference voltage source connected to an input node receiving said input signal; a power source; a bipolar transistor having a base connected to said input node receiving said input signal and to said reference voltage source, and a collector connected to said power source; a resistor connected between an emitter of said bipolar transistor and a circuit ground; and a capacitor connected between the emitter of the bipolar transistor and a circuit ground.

Claim 6

The Schmitt trigger circuit according to claim 1, wherein said maximum voltage detecting means comprises: a reference voltage source connected to an input node receiving said input signal; a power source; a field-effect transistor having a gate connected to said input node receiving said input signal and to said reference voltage source, and a drain connected to said power source; a constant current source connected between a source of said FET and a circuit ground; and a capacitor connected between the source of said FET and a circuit ground.

Claim 7

The Schmitt trigger circuit according to claim 1, wherein said maximum voltage detecting means comprises: a reference voltage source connected to an input node receiving said input signal; a power source; a bipolar transistor having a base connected to said input node receiving said input signal and to said reference voltage source, and a collector connected to said power source; a constant current source connected between an emitter of said bipolar transistor and a circuit ground; and a capacitor connected between the emitter of the bipolar transistor and said power source.

Claim 8

The Schmitt trigger circuit according to claim 1, wherein said minimum voltage detecting means comprises: a reference voltage source connected to an input node receiving said input signal; a power source; a constant current source connected to said power source; a bipolar transistor having a base connected to said input node receiving said input signal and to said reference voltage source, and an emitter connected to said constant current source, and a collector connected to a circuit ground; and a capacitor connected between the emitter of said bipolar transistor and a circuit ground.

Claim 9

The Schmitt trigger circuit according to claim 1, wherein said minimum voltage detecting means comprises: a reference voltage source connected to an input node receiving said input signal; a power source; a resistor connected to said power source; a bipolar transistor having a base connected to said input node receiving said input signal and to said reference voltage source, and an emitter connected to said resistor, and a collector connected to a circuit ground; and a capacitor connected between the emitter of said bipolar transistor and a circuit ground.

Claim 10

The Schmitt trigger circuit according to claim 1, wherein said minimum voltage detecting means comprises: a reference voltage source connected to an input node receiving said input signal; a power source; a constant current source connected to said power source; a field-effect transistor having a gate connected to said input node receiving said input signal and to said reference voltage source, and a source connected to said constant current source, and a drain connected to a circuit ground; and a capacitor connected between the source of said FET and a circuit ground.

Claim 11

The Schmitt trigger circuit according to claim 1, wherein said minimum voltage detecting means comprises: a reference voltage source connected to an input node receiving said input signal; a power source; a constant current source connected to said power source; a bipolar transistor having a base connected to said input node receiving said input signal and to said reference voltage source, and an emitter connected to said constant current source, and a collector connected to a circuit ground; and a capacitor connected between the emitter of said bipolar transistor and said power source.

Claim 12

A Schmitt trigger circuit comprising: an input node receiving an input signal; a reference voltage source connected between said input node receiving said input signal and a circuit ground; maximum voltage detecting means for detecting and retaining a maximum voltage of said input signal; minimum voltage detecting means for detecting and retaining a minimum voltage of said input signal; a first resistor connected at one end to said maximum voltage detecting means a second resistor connected at one end to an other end of said first resistor; a third resistor connected at one end to an other end of said second resistor and at an other end to said minimum voltage detecting means; first voltage comparing means having a first input node, a second input node and an output node, said first input node being connected to a node between said first resistor and said second resistor, and said second input node being connected to said input node of said input signal; second voltage comparing means having a first input node, a second input node and an output node, said first input node being connected to said input node of said input signal, and said second input node being connected to a node between said second resistor and said third resistor; and a flip-flop circuit connected to said output nodes of the first and second voltage comparing means to produce a predetermined output signal.

Claim 13

A Schmitt trigger circuit comprising: an input node receiving an input signal; a reference voltage source connected between said input node receiving said input signal and a circuit ground; maximum voltage detecting means for detecting and retaining a maximum voltage of said input signal; minimum voltage detecting means for detecting and retaining a minimum voltage of said input signal; a first resistor connected at one end to said maximum voltage detecting means a second resistor connected at one end to an other end of said first resistor; a third resistor connected at one end to an other end of said second resistor and at an other end to said minimum voltage detecting means; first voltage comparing means having a first input node, a second input node and an output node, said first input node being connected to a node between said first resistor and said second resistor, and said second input node being connected to said input node of said input signal; second voltage comparing means having a first input node, a second input node and an output node, said first input node being connected to said input node of said input signal, and said second input node being connected to a node between said second resistor and said third resistor; and a flip-flop circuit connected to said output nodes of the first and second voltage comparing means to produce a predetermined output signal.

Claim 14

The Schmitt trigger circuit according to claim 11, wherein said maximum voltage detecting means comprises: a reference voltage source connected to an input node receiving said input signal; a power source; a bipolar transistor having a base connected to said input node receiving said input signal and to said reference voltage source, and a collector connected to said power source; a constant current source connected between an emitter of said bipolar transistor and a circuit ground; and a capacitor connected between the emitter of the bipolar transistor and a circuit ground.

Claim 15

The Schmitt trigger circuit according to claim 11, wherein said minimum voltage detecting means comprises: a reference voltage source connected to an input node receiving said input signal; a power source; a constant current source connected to said power source; a bipolar transistor having a base connected to said input node receiving said input signal and to said reference voltage source, and an emitter connected to said constant current source, and a collector connected to a circuit ground; and a capacitor connected between the emitter of the bipolar transistor and a circuit ground.