Patent ID: 7339398
Filing Date: 2008-03-04
Classification: H03K

Abstract:
1. A driver impedance control apparatus, for dynamically determining the impedance of at least one driver, comprising: a first reference impedance, wherein a first end thereof is coupled to a first voltage, a second end thereof is coupled to a first voltage divide point; a second reference impedance, wherein a first end thereof is coupled to a second voltage, a second end thereof is coupled to a second voltage divide point; a dummy pull-up array, coupled between the first voltage divide point and the second voltage, for determining an impedance of the dummy pull-up array according to a pull-up adjusting signal; a dummy pull-down array, coupled between the second voltage divide point and the first voltage, for determining an impedance of the dummy pull-down array according to a pull-down adjusting signal; a pull-up array control unit, for detecting a voltage of the first voltage divide point, and adjusting the impedance of the dummy pull-up array by providing the pull-up adjusting signal; and a pull-down array control unit, for detecting a voltage of the second voltage divide point, and adjusting the impedance of the dummy pull-down array by providing the pull-down adjusting signal; wherein when the voltage of the first voltage divide point achieves a first target level, and the voltage of the second voltage divide point achieves a second target level, the pull-up array control unit and the pull-down array control unit respectively output a corresponding pull-up setting signal and a corresponding pull-down setting signal to the driver according to impedance states of the dummy pull-up array and the dummy pull-down array, and the driver impedance control apparatus further comprises a register coupled to the pull-up array control unit and the pull-down array control unit for receiving and storing the pull-up setting signal and the pull-down setting signal and providing the stored signals to the driver.