CMOS output buffer with large current pulling ability and low noise

• Main Author: JOU, HUANGNG
• Format: Patent
• Language: English
• Published: 11.09.2000
• Edition: 7
• Subjects: AMPLIFIERS; BASIC ELECTRIC ELEMENTS; BASIC ELECTRONIC CIRCUITRY; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

This invention provides an output buffer with large current driving ability, which can completely avoid the generation of short-circuit current of the driving transistor, and further eliminate the consumption of the short-circuit power. Besides, the circuit provided by this invention can efficiently lower the noise voltage. The output buffer circuit comprises a first and a second driving circuit, which are used to pull up or pull down the voltage level of the output terminal, and respond to the high voltage level of the first output signal or the low voltage level of the second output signal. In general, the first driving circuit is composed by more than one pull-up PMOS transistors, and the second driving circuit is composed by more than one pull-down NMOS transistors. Besides, a first and a second pre-drivers are connected on the first and the second driving circuit respectively. The first pre-driver receives the inverted output of the first output signal and the delay output of the second pre-driver. The second pre-driver receives the invertedoutput of the second output signal and the delay output of the first pre-driver. With such a connection manner, all of the pull-up (or pull-down) transistors are completely shut down and then all of the pull-down (or pull-up) transistors start to be conducted. Therefore, the short-circuit current caused by the change of the state of output signal is eliminated.