Current balancing circuits for light-emitting-diode-based illumination systems

A system comprising:

• a first transistor configured to supply a first current to a first set of light emitting diodes connected to a first terminal of the first transistor, wherein the first set of light emitting diodes is configured to output light having first wavelengths in a first wavelength range in a spectrum of blue light;
• a second transistor configured to supply a second current to a second set of light emitting diodes connected to a first terminal of the second transistor, wherein the second set of light emitting diodes is configured to output light having second wavelengths in a second wavelength range in the spectrum of blue light;
• a third transistor configured to supply a third current to a third set of light emitting diodes connected to a first terminal of the third transistor, wherein the third set of light emitting diodes is configured to output light having third wavelengths in a third wavelength range in the spectrum of blue light, and wherein the third wavelength range is (i) less than the second wavelength range and (ii) greater than the first wavelength range,
• wherein values of the first current, the second current, and the third current are in a predetermined proportion;
• and
• a comparator configured to
• compare a voltage at the first terminal of the first transistor, a voltage at the first terminal of the second transistor, or a voltage at the first terminal of the third transistor to a reference voltage, and
• adjust, based on the comparison, biasing of the first transistor, the second transistor, and the third transistor to maintain the predetermined proportion between the first current, the second current, and the third current,
• wherein a color temperature of white light generated based on the light output by the first, second, and third sets of light emitting diodes depends on the predetermined proportion of the first current, the second current, and the third current.

A system comprising:

• a first transistor configured to supply a first current to a first set of light emitting diodes connected to a first terminal of the first transistor, wherein the first set of light emitting diodes is configured to output light having first wavelengths in a first wavelength range in a spectrum of blue light;
• a second transistor configured to supply a second current to a second set of light emitting diodes connected to a first terminal of the second transistor, wherein the second set of light emitting diodes is configured to output light having the first wavelengths in the first wavelength range in the spectrum of blue light;
• a third transistor configured to supply a third current to a third set of light emitting diodes connected to a first terminal of the third transistor, wherein the third set of light emitting diodes is configured to output light having second wavelengths in a second wavelength range in a spectrum of ultraviolet light,
• wherein values of the first current, the second current, and the third current are in a predetermined proportion;
• and
• a comparator configured to
• compare a voltage at the first terminal of the first transistor, a voltage at the first terminal of the second transistor, or a voltage at the first terminal of the third transistor to a reference voltage, and
• adjust, based on the comparison, biasing of the first transistor, the second transistor, and the third transistor to maintain the predetermined proportion between the first current, the second current, and the third current,
• wherein a color temperature of white light generated based on the light output by the first, second, and third sets of light emitting diodes depends on the predetermined proportion of the first current, the second current, and the third current.

A method comprising:

• supplying a first current to a first load connected to a first terminal of a first transistor;
• supplying a second current to a second load connected to a first terminal of a second transistor, wherein the first current and the second current have a predetermined ratio;
• comparing a voltage at the first terminal of the first transistor or a voltage at the first terminal of the second transistor to a reference voltage;
• and
• adjusting, based on the comparison, biasing of the first transistor and the second transistor to maintain the predetermined ratio between the first current and the second current.

A method comprising:

• supplying a first current to a first set of light emitting diodes connected to a first terminal of a first transistor;
• outputting, from the first set of light emitting diodes, light having first wavelengths in a first wavelength range in a spectrum of blue light;
• supplying a second current to a second set of light emitting diodes connected to a first terminal of a second transistor;
• outputting, from the second set of light emitting diodes, light having the first wavelengths in the first wavelength range in the spectrum of blue light;
• supplying a third current to a third set of light emitting diodes connected to a first terminal of a third transistor;
• outputting, from the third set of light emitting diodes, light having second wavelengths in a second wavelength range in a spectrum of ultraviolet light, wherein values of the first current, the second current, and the third current are in a predetermined proportion;
• comparing a voltage at the first terminal of the first transistor, a voltage at the first terminal of the second transistor, or a voltage at the first terminal of the third transistor to a reference voltage;
• and
• adjusting, based on the comparison, biasing of the first transistor, the second transistor, and the third transistor to maintain the predetermined proportion between the first current, the second current, and the third current,
• wherein a color temperature of white light generated based on the light output by the first, second, and third sets of light emitting diodes depends on the predetermined proportion of the first current, the second current, and the third current.