Abstract: An apparatus includes at least one filter configured to filter a reference voltage to generate a filtered reference voltage. The apparatus also includes an amplifier configured to amplify a difference between the filtered reference voltage and a feedback voltage to generate a drive signal. The apparatus further includes a first transistor configured to generate an output voltage based on the drive signal, where the feedback voltage is based on the output voltage. The apparatus also includes a second transistor configured to generate a first bias current for the amplifier based on the drive signal. In addition, the apparatus includes a voltage-to-current converter configured to generate a second bias current for the amplifier based on the reference voltage and the feedback voltage. The second transistor can generate higher first bias currents during higher load currents, and the voltage-to-current converter can generate higher second bias currents during faster load current variations.

Abstract: A circuit and method for providing voltage regulation that operates with relatively low noise, low power, fast start up and low dropout. The invention includes a constant voltage reference that is coupled to a reference amplifier which amplifies the reference voltage to a selectable level. The output of the reference amplifier is provided to an integrated low pass noise filter which suppresses at least the noise generated by the constant voltage reference and the reference amplifier. The output of the integrated noise filter is provided to the inverting input of an error amplifier, whose non-inverting input is coupled to the output voltage (VOUT). Also, the output of the error amplifier is coupled to a gate of a pass transistor that is coupled between the input voltage (VIN) and the output voltage (VOUT) of the invention.