Display driver

An LCD display system, comprising:

• an LCD (liquid crystal display);
• an LCD display driver including,
• multiple LCD source driver circuits, and
• a gamma reference circuit;
• each LCD source driver circuit to
• convert video image data input to the LCD display driver into N analog gray-level gamma-adjusted source voltage signals output to the LCD, each based on a respective one of N gamma reference voltages, and
• drive out the gamma-adjusted source voltage signals to the LCD;
• the gamma reference circuit to generate the N gamma reference voltages based on at least one pre-defined gamma curve that includes the N (0 to N−1) gamma reference voltages divided into M−1 regions defined by M breakpoint voltages corresponding to M−1 segments of the gamma curve, including
• a gamma-breakpoint circuit, including
• a range resistor string with a sequence of voltage taps;
• M breakpoint digital-to-analog converters (DACs), designated DAC(1) to DAC(M), wherein
• each breakpoint DAC including inputs coupled to a respective subset of the voltage taps of the range resistor string, where at least some of the M subsets of voltage taps overlap, and
• each breakpoint DAC to output a respective breakpoint voltage based on the respective subset of voltage taps, including
• a breakpoint voltage BP(1) from breakpoint DAC(1) and a breakpoint voltage BP(M) from a breakpoint DAC (M), and
• intermediate breakpoint voltages BP(2) to BP(M−1) from respectively breakpoint DAC(2) to DAC(M−1);
• and
• a gamma-reference output circuit to generate the N gamma reference voltages, including
• a reference resistor string having a set of reference voltage taps, and
• N reference multiplexers, designated MUX(0) to MUX(N−1) each to select from a subset of the reference voltage taps of the reference resistor string, and to generate at an output a respective one of the N gamma reference voltages,
• the reference resistor string including a first end point provided by the breakpoint voltage BP(1) from DAC(1), and a second end point provided by the breakpoint voltage BP(M) from DAC(M),
• M−2selected reference multiplexers designated MUX(2) to MUX(M−1) each having its output coupled respectively to the intermediate breakpoint voltages BP(2) to BP(M−1) from DAC(2) to DAC(M−1).

A method for use in a system with an LCD (liquid crystal display), comprising:

• converting video image data into N analog gray-level gamma-adjusted source voltage signals for input to the LCD, each based on a respective one of N gamma reference voltages, and
• generating the N gamma reference voltages based on at least one pre-defined gamma curve that includes the N (0 to N−1) gamma reference voltages divided into M−1 regions defined by M breakpoint voltages corresponding to M−1 segments of the gamma curve, including generating the M breakpoint voltages designated BP(1) to BP(M) using M respective range decoders with inputs coupled to a respective subset of voltage taps of a range resistor string, where at least some of the M subsets of voltage taps overlap;
• generating the N gamma reference voltages using N reference multiplexers, each to select from a respective subset of reference voltage taps of a reference resistor string,
• the reference resistor string including a first end point provided by the breakpoint voltage BP(1), and a second end point provided by the breakpoint voltage BP(M),
• the N reference multiplexers including M−2 selected reference multiplexers with outputs respectively couple to intermediate breakpoint voltages BP(2) to BP(M−1).