US 5,184,033 A · Regulated BiCMOS output buffer

Abstract

A regulated BiCMOS output buffer (34) regulates a logic high voltage of an output signal to improve interfacing to loads such as 3.3 volt integrated circuits. The output buffer (34) provides a first voltage to a base of a pullup transistor (116) in response to a difference between an input voltage and a reference voltage. An emitter of the pullup transistor (116) provides an output signal. A second transistor (102) having characteristics matching those of the pullup transistor (116) receives the first voltage at its base, and provides the input voltage at its emitter. The output buffer (34) changes the first voltage until the voltage at the base of the second transistor (102) equals the reference voltage. Thus, signal reflections on the output signal do not affect the performance of the output buffer. Clamps (99, 120) coupled to the base and emitter of the pullup transistor (116) provide soft clamping according to a square law.

Claims15

Dependent claims

A regulated BICMOS output buffer comprising:

a difference amplifier for providing a first voltage signal in response to a difference between first and second input voltages, said first input voltage being a reference voltage;
a first transistor having a collector coupled to a first power supply voltage terminal, a base for receiving said first voltage signal, and an emitter coupled to a bonding pad;
a second transistor having a first current electrode coupled to said bonding pad, a control electrode for receiving a data signal, and a second current electrode coupled to a second power supply voltage terminal;
and
a third transistor having a collector coupled to said first power supply voltage terminal, a base for receiving said first voltage signal, and an emitter for providing said second input voltage of said difference amplifier.

2 more elements

A regulated BICMOS output buffer comprising:

a difference amplifier for providing a first voltage signal in response to a difference between first and second input voltages, said first input voltage being a reference voltage;
a first transistor having a collector coupled to a first power supply voltage terminal, a base for receiving said first voltage signal, and an emitter;
a resistor having a first terminal coupled to said emitter of said first bipolar transistor, and a second terminal for providing an output signal;
a second transistor having a first current electrode coupled to said second terminal of said resistor, a control electrode for receiving a data signal, and a second current electrode coupled to a second power supply voltage terminal;
and
a third transistor having a collector coupled to said first power supply voltage terminal, a base for receiving said first voltage signal, and an emitter for providing said second input voltage of said difference amplifier.

3 more elements

Dependencies are inferred from the claim text.

Regulated BiCMOS output buffer

Life of this patent

Regulated BiCMOS output buffer

Life of this patent

Abstract

Claims15