Patent ID: 8159300
Filing Date: 2012-04-17
Classification: H03F

Abstract:
1. A signal conversion circuit, which takes as input a differential voltage signal to a first input terminal and a second input terminal, converts a common-mode voltage level of the differential voltage signal, and outputs the differential voltage signal having the converted common-mode voltage level from a first output terminal and a second output terminal, the signal conversion circuit comprising: first and second impedance elements that are connected in series between a low-potential side power supply and the first output terminal; third and fourth impedance elements that are connected in series between the low-potential side power supply and the second output terminal; a first PMOS transistor that has a drain electrode connected to the first output terminal, a gate electrode connected to the second input terminal, and a source electrode; a second PMOS transistor that has a drain electrode connected to the second output terminal, a gate electrode connected to the first input terminal, and a source electrode; a first NMOS transistor that has a source electrode connected between the first and second impedance elements, a gate electrode connected to the first input terminal, and a drain electrode connected to a high-potential side power supply; a second NMOS transistor that has a source electrode connected between the third and fourth impedance elements, a gate electrode connected to the second input terminal, and a drain electrode connected to the high-potential side power supply; and a current source that is connected-between the source electrode of the first PMOS transistor and the source electrode of the second PMOS transistor, and the high-potential side power supply and generates a constant current.