The present invention relates to an operational amplifier, including: a symmetrical differential amplifier; a local common mode feedback circuit coupled to the symmetrical differential amplifier; a tail current source circuit including at least one first transistor and a second transistor and a current source resistor. The tail current source circuit is configured to adjust a control voltage of the first transistor by using the second transistor such that a predetermined reference current flows through a load path of the first transistor.

Systems and methods are provided for controlling power down of an overdrive low drop out regulator circuits. The system is designed with a low dropout regulator circuit configured to operate in a safe operating area range of operation with very low current. The circuit contains a regulator, a current boost, and a power down switch. The current boost is responsive to a power down signal, generally from a power distribution board. The circuit is fabricated such that the low dropout regulator circuit with the current boost operates with minimum current pull while maintaining safe operating area range of operation. The safe operating area range of operation is maintained during various design operations, normal operations, and power down. This regulator circuit may be designed without a middle level voltage or high-ground.

Devices and methods include voltage buses. The devices also include one or more power amplifiers coupled to the voltage bus. Each of the one or more power amplifiers include one or more transistors. The devices also include a model that is configured to emulate leakage from at least one of the one or more transistors. A current mirror with a first transistor coupled to the model and a second transistor coupled to the voltage bus. The current mirror is configure to draw charge from the voltage bus based at least in part on the emulated leakage from the model.

In an example, a system includes an amplifier configured to produce a bandgap voltage reference. The system also includes a current source configured to provide a current to bias the amplifier. The system includes a switching circuit configured to receive a first current replica signal and a second current replica signal, the switching circuit further configured to cause the current source to provide the current to bias the amplifier based on either the first current replica signal or the second current replica signal.

A bias circuit is provided. The bias circuit may include a first transistor forming an input node, a second transistor forming an output node, and a switch array disposed between the first transistor and the second transistor. The switch array may be configured to charge the first transistor to a supply voltage and the second transistor to a ground during a first mode of operation, and couple the first transistor to the second transistor to approximate a final bias voltage during a second mode of operation.

A noise filtering circuit including: an amplifier which receives a reference bias through a first input terminal, generates an amplified output voltage and outputs the amplified output voltage through an output terminal, and receives an output voltage generated on the basis of the amplified output voltage through a second input terminal; a resistance component connected between the output terminal of the amplifier and the second input terminal; and a capacitor connected to the resistance component.

The present disclosure provides a bias generating device and a method for generating bias. A bias generating device includes a first diode-connected transistor pair connected to receive a first voltage; a second diode-connected transistor pair connected to receive a second voltage; and a first transistor pair connected to the first diode-connected transistor pair and the second diode-connected transistor pair. The first transistor pair is configured to generate a third voltage in response to the first voltage and the second voltage.

A device for controlling a first voltage with a second voltage includes a first terminal of application of the second voltage and a second terminal for supplying the first voltage. A comparator has a first input terminal connected to the first terminal and has a second input terminal receiving information representative of the first voltage. At least one first current source of programmable intensity is connected to the second input terminal of the comparator.

A reference generator circuit included in a computer system may employ multiple field-effect transistors to generate a reference voltage whose value is based on the threshold voltages of the multiple field-effect transistors. The reference generator circuit can include a current source that generates a bias current. One of more stages included in the reference generator circuit can generate, using the bias current, respective output voltages whose values are based on differences in threshold voltages of field-effect transistors included in the stages. The output voltages can be combined to generate different reference voltage values.

Disclosed is a low dropout linear voltage regulator and a control circuit thereof. The control circuit comprises an error amplifier, a foldback current-limiting protection circuit, an undershoot suppression circuit and an output detection circuit. The foldback current-limiting protection circuit limits the output current of power transistor and performs short circuit protection, the undershoot suppression circuit pulls the control terminal of the power transistor to low voltage level when the output voltage undershoots. The output detection circuit judges whether the output voltage rises to a preset voltage value in the startup stage, and before the output voltage rises to the preset voltage value, disables the undershoot suppression circuit and the foldback characteristic of the foldback current-limiting protection circuit, which can prevent normal startup of the circuit from being affected by a maloperation of the foldback current-limiting protection circuit and the undershoot suppression circuit during the startup process, improve on-load startup ability.