Patent ID: 8648585

Claim:
A constant current source circuit comprising: a control voltage generation section that detects an output voltage at an output terminal and generates a control voltage based on the detected output voltage; a reference current adjustment section that adjusts a reference current based on the control voltage; and a current mirror section that outputs an output current in response to the adjusted reference current at the output terminal, wherein the reference current adjustment section includes a first transistor configured of a p-channel MOS transistor in which a source thereof is connected to a voltage supply and a gate thereof receives a first bias voltage; a second transistor configured of a p-channel MOS transistor in which a source thereof is connected to a drain of the first transistor and a gate thereof receives the control voltage; a third transistor configured of a p-channel MOS transistor in which a source thereof is connected to the source of the second transistor, a gate thereof receives a second bias voltage, and a drain thereof is connected to a drain of the second transistor, and wherein the current mirror section includes a fourth transistor configured of an n-channel MOS transistor in which a drain thereof is connected to the drain of the third transistor, a gate thereof is connected to the drain thereof, and a source thereof is grounded; a fifth transistor configured of an n-channel MOS transistor in which a drain thereof is connected to the output terminal, and a gate thereof receives a third bias voltage; and a sixth-A transistor configured of an n-channel MOS transistor in which a drain thereof is connected to the source of the fifth transistor, and a gate thereof is connected to the gate of the fourth transistor.