Patent ID: 7692454

Claim:
A signal conversion circuit, which takes as input differential voltage signals to a first input terminal and a second input terminal, converts the common-mode voltage level of the differential voltage signals, and outputs differential voltage signals, with said converted common-mode voltage level, from a first output terminal and a second output terminal, comprising: a first resistor, one end of which is connected to a high-potential side of a power supply, and the other end of which is connected to said first output terminal; a second resistor, one end of which is connected to said high-potential side of the power supply, and the other end of which is connected to said second output terminal; a first NMOS transistor, having a drain electrode connected to said first output terminal, a gate electrode connected to said second input terminal, and a source electrode; a second NMOS transistor, having a drain electrode connected to said second output terminal, a gate electrode connected to said first input terminal, and a source electrode; a first PMOS transistor, having a source electrode connected to said first output terminal, a gate electrode connected to said first input terminal, and a drain electrode connected to a low-potential side of the power supply; a second PMOS transistor, having a source electrode connected to said second output terminal, a gate electrode connected to said second input terminal, and a drain electrode connected to said low-potential side of the power supply; and a current source, which is provided between the source electrode of said first NMOS transistor and source electrode of said second NMOS transistor on the one hand, and said low-potential side of the power supply on the other, and which generates a constant current, wherein the drain electrode of the first PMOS transistor is connected to said low-potential side of the power supply without having said current source in between, and wherein the drain electrode of the second PMOS transistor is connected to said low-potential side of the power supply without having said current source in between.