Apparatus and method for controlling gray level for display panel

An apparatus for controlling brightness of a plurality of light-emitting pixels in a display panel, the apparatus comprising:

• a switch for switching bits in a data line according to control information provided by a scan line;
• a pulse modulator in communication with the switch for pulse modulating the bits in the data line prior to the bits being switched by the switch, the pulse modulator comprising:
• a controller for dividing the data line to first N bits and second N bits;
• a pulse amplitude modulator (PAM) for pulse amplitude modulating the first N bits of the data line;
• a pulse width modulator (PWM) for pulse width modulating the second N bits of the data line;
• and
• a driver for receiving the first N bits of the data line and the second N bits of the data line in response to activation of the switch by the scan line, wherein the driver controls the gray scale of a corresponding pixel based on the first N bits and the second N bits of the data line,
• wherein the pulse amplitude modulator (PAM) comprises N transistors for respectively pulse amplitude modulating the first N bits of the data line to control current intensity for the corresponding pixel, wherein the current intensity of the corresponding pixel is controlled between approximately 1 μA and 15 μA, and
• wherein the pulse width modulator (PWM) comprises a switching transistor for pulse width modulating the second N bits of the data line for maintaining the pulse for a set time at a first level to control a drive time for the corresponding pixel, wherein pulse width for the second N bits is between approximately 1 μs and 8 μs,
• such that gray level for the display panel is controlled between approximately 50 nA and 100 nA.