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LDO and load switch supporting a wide range of load capacitance

  • US 9,710,003 B2
  • Filed: 03/14/2014
  • Issued: 07/18/2017
  • Est. Priority Date: 03/14/2013
  • Status: Active Grant
First Claim
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1. A low drop-out (LDO) load switch linear voltage regulator (LVR) circuit having an open loop transfer function, comprising:

  • a feedback network comprising;

    a first input coupled to an output of the LVR circuit;

    a second input coupled to a reference voltage; and

    an output; and

    a pass transistor comprising;

    a gate terminal driven by the output of the feedback network;

    a first terminal coupled to an input of the LVR circuit; and

    a second terminal coupled to the output of the LVR circuit,wherein the feedback network further comprises an output scaling network, an error amplifier, a first buffer, a second buffer, a capacitor, and a zero generation circuit that is connected to the first buffer and the second buffer, and is configured to generate a zero,wherein the first buffer comprises;

    an input coupled to an output of the error amplifier and an input of the second buffer; and

    an output coupled to a first terminal of the capacitor,wherein the error amplifier comprises;

    a first input for receiving the reference voltage; and

    a second input coupled to an output of the output scaling network,wherein the capacitor comprises;

    the first terminal connected to the output of the first buffer; and

    a second terminal connected to the output of the LVR,wherein the second buffer comprises an output driving the gate terminal of the pass transistor, andwherein the output scaling network comprises;

    an input connected to the output of the LVR; and

    the output connected to the second input of the error amplifier, wherein the output scaling network is configured to scale down an output voltage level of the LVR, using a resistive divider, andwherein the input of the first buffer is coupled to the output of the error amplifier and the input of the second buffer via the zero generation circuit.

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