Current drive circuit, light emitting element drive circuit and digital-analog converter

A current drive circuit comprising:

• a current source that produces a varying source current;
• an output current control circuit that temporarily supplies a boost current having a value corresponding to that of the source current;
• a current output circuit that amplifies the source and boost currents in accordance with an external signal, the current output circuit comprising:
• a first current mirror circuit that amplifies the
• source current to produce a first amplified current, and
• a second current mirror circuit that amplifies the first amplified current and the boost current to produce a drive circuit output current;
• and
• a pulse generation circuit that generates first and second signals from the external signal, the second signal rises in synchronization with the first signal and falls before the first signal, wherein:
• the first and second current mirror circuits operate at a time of rise in the first signal,
• the output current control circuit comprises a third current mirror circuit that operates at a time of rise in the second signal and has a current input part and a current output part respectively connected to the current source and a point of connection between the first and second current mirror circuits and
• the output current control circuit temporarily supplies the boost current at a time of rise in the drive circuit output current so as to increase the rate of rise in the drive circuit output current.

A light emitting element drive circuit, comprising:

• a current source that produces a varying source current;
• an output current control circuit that temporarily supplies a boost current having a value corresponding to that of the source current;
• a current output circuit that amplifies the source and boost currents in accordance with an external signal for supplying the amplified current to a light emitting element, the current output circuit comprising:
• a first current mirror circuit that amplifies the source current to produce a first amplified current, and
• a second current mirror circuit that amplifies the first amplified current and the boost current to produce a drive circuit output current;
• a first switching element that has switch poles respectively connected to a current output part of the first current mirror circuit and a first power supply voltage;
• and
• a second switching element that has switch poles respectively connected to a current input part of the second current mirror circuit and a second power supply voltage, wherein:
• the first and second switching elements switch and operate in opposite phases in accordance with the external signal,
• the first switching element raises an output current of the first current mirror circuit when turned on,
• the second switching raises an output current of the second current mirror circuit when turned off, and
• the output current control circuit temporarily supplies the boost current at a time of rise in the drive circuit output current so as to increase the rate of rise in the drive circuit output current.

A light emitting element drive circuit comprising:

• a current source that produces a varying source current;
• an output current control circuit that temporarily supplies a boost current having a value corresponding to that of the source current;
• a current output circuit that amplifies the source and boost currents in accordance with an external signal, the current output circuit comprising:
• a first current mirror circuit that amplifies the source current to produce a first amplified current, and
• a second current mirror circuit that amplifies the first amplified current and the boost current to produce a drive circuit output current;
• and
• a pulse generation circuit that generates first and second signals from the external signal, the second signal rises in synchronization with the first signal and falls before the first signal, wherein:
• the first and second current mirror circuits operate at a time of rise in the first signal,
• the output current control circuit comprises a third current mirror circuit that operates at a time of rise in the second signal and has a current input part and a current output part respectively connected to the current source and a point of connection between the first and second current mirror circuits, and
• the output current control circuit temporarily supplies the boost current at a time of rise in the drive circuit output current so as to increase the rate of rise in the drive circuit output current.

A digital-analog converter comprising:

• a current source that produces an analog source current corresponding to the bit weight of a two-value digital value;
• an output current control circuit that temporarily supplies a boost current having a value corresponding to that of the source current;
• a current output circuit that amplifies the source and boost currents in accordance with an external signal, the current output circuit comprising:
• a first current mirror circuit that amplifies the source current to produce a first amplified current, and
• a second current mirror circuit that amplifies the first amplified current and the boost current to produce a drive circuit output current;
• a first switching element that has switch poles respectively connected to a current output part of the first current mirror circuit and a first power supply voltage;
• and
• a second switching element that has switch poles respectively connected to a current input part of the second current mirror circuit and a second power supply voltage, wherein:
• the first and second switching elements switch and operate in opposite phases in accordance with the external signal,
• the first switching element raises an output current of the first current mirror circuit when turned on,
• the second switching raises an output current of the second current mirror circuit when turned off, and
• the output current control circuit temporarily supplies the boost current at a time of rise in the drive circuit output current so as to increase the rate of rise in the drive circuit output current.

A digital-analog converter comprising:

• a current source that produces a varying source current;
• an output current control circuit that temporarily supplies a boost current having a value corresponding to that of the source current;
• a current output circuit that amplifies the source and boost currents in accordance with an external signal, the current output circuit comprising:
• a first current mirror circuit that amplifies the source current to produce a first amplified current, and
• a second current mirror circuit that amplifies the first amplified current and the boost current to produce a drive circuit output current;
• and
• a pulse generation circuit that generates first and second signals from the external signal, the second signal rises in synchronization with the first signal and falls before the first signal, wherein:
• the first and second current mirror circuits operate at a time of rise in the first signal,
• the output current control circuit comprises a third current mirror circuit that operates at a time of rise in the second signal and has a current input part and a current output part respectively connected to the current source and a point of connection between the first and second current mirror circuits, and
• the output current control circuit temporarily supplies the boost current at a time of rise in the drive circuit output current so as to increase the rate of rise in the drive circuit output current.