Abstract: An apparatus for driving a pulse width modulation reference signal includes: (a) A converting unit receiving an input signal at an input locus and presenting an output current at an output locus. The input signal varies at a first frequency. The output current is substantially related with the first frequency. (b) A capacitive element coupled with the output locus for charging by the output current. The pulse width modulation reference signal is related with voltage across the capacitive element.

Abstract: A code-controlled voltage divider (20) is disclosed. The voltage divider (20) includes an upper portion with a resistor (22) and a dummy switching transistors (23), which is biased to be in an on-state. A lower portion of the voltage divider (20) includes multiple parallel legs, each including a resistor (24) and a corresponding switching transistor (26) that has its gate receiving one bit of a digital control word. A decoder (30) may be provided within the voltage divider (20) to generate the digital control word from an incoming code word, for example from a central processing unit (10). The lower portion resistors (24) of the voltage divider (20) are binary-weighted, and the sizes of the corresponding switching transistors (26) are binary-weighted so that the portion of the series resistance of each parallel leg that is due to the on-resistance of the switching transistor (26) is substantially constant over all of the parallel legs.