Source follower startup regulator circuitry

A device comprising:

• a circuit having a first input, a second input, and an output, and including:
• a first source follower circuit having a first input and a first output, the first input coupled to the first input of the circuit, the first source follower circuit configurable to set a state of the first output responsive to a state of the first input of the circuit;
• a second source follower circuit having a second input and a second output, the second input coupled to an output of the circuit, the second source follower circuit configurable to set a state of the second output responsive to a state of the output of the circuit;
• an amplifier including inputs and outputs, the inputs of the amplifier coupled to the first output of the first source follower circuit and the second output of the second source follower circuit, wherein the amplifier is configurable to control an output voltage at the output of the circuit responsive to states of at least one of the outputs of the amplifier;
• bias circuitry coupled to the second input;
• and
• a cascode network coupled between the amplifier and the bias circuitry.

A system comprising:

• a reference circuit coupled to a power input;
• a regulator circuit having a reference input and an output, the reference input coupled to an output of the reference circuit, the regulator circuit including:
• a first source follower circuit having an input and an output, the input of the first source follower circuit coupled to the reference input;
• a second source follower circuit having an input and an output, the input of the second source follower circuit coupled to the output of the regulator circuit, the second source follower circuit configurable to set a state of the output of the second source follower circuit responsive to a state of the output of the regulator circuit;
• a bias circuit coupled between the power input, wherein the bias circuit includes a current mirror and a cascode network;
• an amplifier circuit coupled to the current mirror via at least part of the cascode network and has a first input, a second input, and an output, the first input coupled to the output of the first source follower circuit, the second input coupled to the output of the second source follower circuit, and the output of the amplifier circuit coupled to the output of the regulator circuit;
• and
• a transistor coupled between the power input and the output of the regulator circuit, the transistor having a control terminal coupled to the output of the amplifier circuit;
• and
• a gate driver circuit coupled to the output of the regulator circuit.