Ablic Inc.

Seiko Instruments Inc

Sii Semiconductor Corporation

Tadashi Kurozo

Takao Nakashimo

Tomoyuki Yokoyama

Takashi Imura

Michiyasu Deguchi

Toshiyuki Tsuzaki

Manabu Fujimura

Hideyuki Sawai

Yotaro Nihei

A low pass filter and a semiconductor device including the low pass filter are capable of quickly reaching a steady state upon power-on. The low pass filter includes a first first-conductivity-type MOS transistor, an electrostatic capacitor, a buffer circuit, a bias circuit, an input terminal, and an output terminal. The input terminal is connected to a source terminal of the first first-conductivity-type MOS transistor. A drain terminal of the first first-conductivity-type MOS transistor is connected to a first terminal of the electrostatic capacitor, the output terminal, and an input terminal of the buffer circuit. An output terminal of the buffer circuit is connected to an input terminal of the bias circuit. An output terminal of the bias circuit is connected to a gate terminal of the first first-conductivity-type MOS transistor.

Low pass filter and semiconductor device

Provided is a voltage regulator having satisfactory transient response characteristics. The voltage regulator includes: a first amplifier for detecting that undershoot occurs in an output voltage; a second amplifier for detecting that overshoot occurs in the output voltage; a first constant current circuit for increasing a bias current of an error amplifier circuit by a first amount for a first time period in response to a signal determined based on one of an output signal of the first amplifier and an output signal of the second amplifier; a second constant current circuit for increasing the bias current of the error amplifier circuit by a second amount larger than the first amount for a second time period shorter than the first time period in response to a signal determined based on the output signal of the first amplifier; and a first switch circuit for pulling up a gate of an output transistor in response to a signal determined based on the output signal of the second amplifier.

Voltage regulator

Provided is a voltage regulator capable of stably suppressing overshoot. The voltage regulator includes a non-regulated state detection circuit for detecting a non-regulated state, and an overshoot suppression circuit. The overshoot suppression circuit is configured to operate when the non-regulated state detection circuit detects the non-regulated state.

Voltage regulator including a non-regulated state detection circuit

Provided is a voltage regulator having a simple circuit configuration in which a protection circuit is not erroneously operated, and delay time of activation of the protection circuit is short. The voltage regulator includes: a protection circuit configured to control an output transistor when an abnormality of the voltage regulator is detected; a first constant current circuit configured to supply operating current to the protection circuit; and a detection circuit configured to detect output current flowing through the output transistor, to thereby control the first constant current circuit. The detection circuit is further configured to detect the output current with a predetermined reference current value. The protection circuit is further configured to control the output transistor so that the output current does not fall below the reference current value.

Short activation time voltage regulator

Provided is a voltage regulator that is low in current consumption and is capable of suppressing the occurrence of an excessive overshoot at an output terminal when a power supply voltage becomes high in a non-regulated state. The voltage regulator includes: an overshoot limiting circuit for detecting an occurrence of an overshoot in an output voltage and limiting a current of the output transistor; and a non-regulated state detection circuit for detecting a non-regulated state of the voltage regulator based on a voltage of an output terminal and a current flowing through the output transistor. The overshoot limiting circuit has an operating current controlled by a detection signal of the non-regulated state detection circuit.

Provided is a voltage regulator capable of performing appropriate phase compensation. Even when a difference between an input voltage and an output voltage is small, an appropriate phase compensation voltage based on an output voltage (Vout) is generated in a resistor circuit (), and the appropriate phase compensation voltage is applied to a phase compensation capacitor (). Accordingly, the voltage regulator is capable of performing appropriate phase compensation.

Growing community of inventors

Chiba, Japan

Tadashi Kurozo