Patent ID: 6114844
Filing Date: 2000-09-05
Classification: G05F

Abstract:
An output driver with driving and filtering capability, comprising:an operational amplifier having a first input for receiving a first input voltage (V.sub.1), a second input for receiving a second input voltage (V.sub.2), and an output for generating an output voltage (Vc); anda transistor having an input terminal coupled to the output of the operational amplifier for receiving the output voltage (Vc), a first terminal coupled to a differential pair, and a second terminal coupled to the second input of the operational amplifier, wherein an output current (I.sub.out) flows across the transistor;a first resistor coupled to the first input of the operational amplifier and having a first resistive value;a control current source coupled to the first resistor and to the first input of the operational amplifier and configured to provide a variable control current (I.sub.CONTROL);a second resistor coupled to the second input of the operational amplifier and the second terminal of the transistor and having a second resistive value;wherein a value of the output current (I.sub.out) is determined by the first resistive value, the second resistive value and the variable control current (I.sub.CONTROL);wherein the variable control current (I.sub.CONTROL) is a variable value that is dependent on an internal reference voltage value (V.sub.Bandgap) and a variable resistive value (R.sub.external), and wherein the variable control current (I.sub.CONTROL) is substantially independent of process, temperature, and supply voltage variations;wherein the variable control current (I.sub.CONTROL) determines a value of the first input voltage (V.sub.1);wherein the output voltage (Vc) controls the transistor so that the second voltage (V.sub.2) becomes equal to the first voltage (V.sub.1).