US 6,982,590 B2
Bias current generating circuit, laser diode driving circuit, and optical communication transmitter
Toshiki Seshita, Kanagawa (Japan)
Assigned to Kabushiki Kaisha Toshiba, Tokyo (Japan)
Filed on Feb. 18, 2004, as Appl. No. 10/779,653.
Claims priority of application No. 2003-124034 (JP), filed on Apr. 28, 2003.
Prior Publication US 2005/0104652 A1, May 19, 2005
Int. Cl. G05F 1/10 (2006.01)
U.S. Cl. 327—539 16 Claims
OG exemplary drawing
 
1. A bias current generating circuit comprising:
a bandgap reference circuit connected to a high power supply voltage terminal for receiving a high power supply voltage and a low power supply voltage terminal for receiving a low power supply voltage, and having a first output terminal for outputting a first voltage which is constant regardless of a temperature, and a second output terminal for outputting a second voltage which changes in accordance with a temperature;
a first low-potential-side constant-current source circuit which includes a first resistor connected between said low power supply voltage terminal and a first terminal, and a first current path connected between said first terminal and a first current supply terminal, receives the second voltage as a reference potential, and outputs a first electric current dependent on a temperature and corresponding to said first resistor from said first current supply terminal;
a second low-potential-side constant-current source circuit which includes a second resistor connected between said low power supply voltage terminal and a second terminal, and a second current path connected between said second terminal and a second current supply terminal, receives the first voltage as a reference potential, and outputs a second electric current independent of a temperature and corresponding to said second resistor from said second current supply terminal;
a third resistor having one end connected to said high power supply voltage terminal;
a third low-potential-side constant-current source circuit which is connected between the other end of said third resistor and said low power supply voltage terminal, receives the first voltage as a reference potential, and supplies a temperature-independent third electric current to said third resistor;
a high-potential-side constant-current source circuit which includes a fourth resistor connected between said high power supply voltage terminal and a third terminal, and a third current path connected between said third terminal and a third current supply terminal, receives a third voltage at the other end of said third resistor as a reference potential, and outputs a fourth electric current independent of a temperature and corresponding to said fourth resistor from said third current supply terminal; and
a current mirror circuit which is connected to said high power supply voltage terminal to receive the high power supply voltage, and generates a bias current in accordance with an electric current supplied from a reference current terminal,
wherein said first, second, and third current supply terminals are connected to said reference current terminal.