Realtek Semiconductor Inc.

Chien-Hui Tsai

Yung-Tai Chen

Hung-chen Chu

Hung-Chen Chu

A level shifter can achieve a level shift by a wide margin. The level shifter includes a latch circuit, a protection circuit, and an input circuit. The latch circuit is coupled between a high-voltage terminal and the protection circuit. The protection circuit including a first protection transistor pair and a second protection transistor pair is set between the latch circuit and the input circuit, and is configured to prevent an excessive voltage drop between the input circuit and a pair of output terminals, wherein the pair of output terminals is set between the first and the second protection transistor pairs and used for outputting a pair of output signals. The input circuit includes an input transistor pair coupled between the second protection transistor pair and a low-voltage terminal and configured to operate according to a pair of input signals.

Level shifter

An output stage of an Ethernet transmitter is provided. The output stage is coupled to a resistor and includes a first output terminal, a second output terminal, a first transistor, and a first transistor group. The resistor is coupled between the first output terminal and the second output terminal. The first transistor has a first source, a first drain, and a first gate, the first source being coupled to a first reference voltage and the first drain being coupled to the second output terminal. The first transistor group is coupled to the first reference voltage and the first output terminal. The first transistor group includes multiple transistors which are connected in parallel, and the magnitude of the current flowing to the first output terminal is related to the number of transistors that are turned on.

Output stage of ethernet transmitter

A transmitter circuit is provided. The transmitter circuit has a first transmission node and a second transmission node and includes a first resistor, a second resistor, a third resistor, a fourth resistor, and a driving circuit. The driving circuit includes a first transistor group, a second transistor group, a third transistor group, and a fourth transistor group. The first resistor is coupled between a first output terminal and the first transmission node. The second resistor is coupled between a second output terminal and the second transmission node. The third resistor is coupled between a third output terminal and the first transmission node. The fourth resistor is coupled between a fourth output terminal and the second transmission node. The first, second, third, and fourth transistor groups are coupled to a first and a second reference voltages and electrically connected to the first, second, third, and fourth output terminals, respectively.

Transmitter circuit

A level shifter can achieve a level shift by a wide margin. The level shifter includes a latch circuit, a clamping circuit, a protection circuit, and an input circuit. The latch circuit is coupled between a high-voltage terminal and a pair of output terminals for outputting a pair of output signals. The clamping circuit is coupled between a medium-voltage terminal and the pair of output terminals and limits the minimum voltage of the pair of output signals to the medium voltage. The protection circuit is set between the latch circuit and the input circuit, and prevents an excessive voltage drop between the input circuit and the pair of output terminals. The input circuit includes an input transistor pair coupled between the protection circuit and a low-voltage terminal having a low voltage. The input transistor pair receives a pair of input signals and operates accordingly.

A transmission-end impedance matching circuit operates according to a signal of an overvoltage signal source and includes a first level shifter, a voltage generating circuit, and an impedance matching circuit. The first level shifter generates a first conversion voltage according to a source signal and operates between a first high voltage and a ground voltage. The voltage generating circuit generates a second high voltage according to the first conversion voltage, the first high voltage, and a medium voltage. The impedance matching circuit includes a second level shifter, a transistor, and two resistors. The second level shifter generates a gate voltage according to the second high voltage, a low voltage, and an input signal. The transistor is turned on/off according to the gate voltage and has a withstand voltage lower than the first high voltage. Each of the two resistors is coupled between the transistor and a differential signal transmission end.

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Hsinchu, Taiwan

Chien-Hui Tsai