Input circuit

• US 10,355,675 B2
• Filed: 09/15/2016
• Issued: 07/16/2019
• Est. Priority Date: 09/24/2015
• Status: Active Grant

• Current Assignee: Ablic Inc. (Minebea Mitsumi, Inc.)
• Original Assignee: Ablic Inc. (Minebea Mitsumi, Inc.)
• Inventors: Sugiura, Masakazu, Tomioka, Tsutomu
• Primary Examiner(s): Houston, Adam D
• Application Number:
  US15/266,525
• Publication Number:
  US 20170093378A1
• Time in Patent Office: 1,034 Days
• Field of Search: 327108-112
• CPC Class Codes: H03K 3/3565 Bistables with hysteresis, e.g. Schmitt trigger

Abstract

To provide an input circuit which avoids power supply voltage dependency of a threshold of the input circuit when an output signal is transited. There is provided an input circuit equipped with an input transistor and a current source connected in series between a first power supply and a second power supply. The input circuit is configured in such a manner that an input signal is inputted to a gate of the input transistor and a signal of a connection point between the input transistor and the current source is outputted as an output signal, and a current value of the current source is changed based on the output signal.

Claims

1. An input circuit comprising:

an input transistor and a current source connected in series between a first power supply and a second power supply,

wherein an input signal is input to a gate of the input transistor,

wherein a signal of a connection point between the input transistor and the current source is output as an output signal, and the output signal is connected to a control point of the current source, and

wherein a current value of the current source is changed based on the output signal and a threshold value of the input circuit is determined by the current value of the current source.

4. The input circuit according to claim 1, further comprising a conductivity type transistor, different from the input transistor, connected between the first power supply and the current source and having a gate connected to the gate of the input transistor.

2. An input circuit comprising:

an input transistor and a current source connected in series between a first power supply and a second power supply, the current source including a plurality of depletion-type transistors connected in series or parallel and having commonly connected gate electrodes,

wherein an input signal is input to a gate of the input transistor,

wherein a signal of a connection point between the input transistor and the current source is output as an output signal, and the output signal is connected to a control point of the current source, and

wherein a current value of the current source is changed based on the output signal and a threshold value of the input circuit is determined by the current value of the current source.

3. The input circuit according to claim 2, wherein the current source further comprises a switch that activates at least one of the plurality of depletion-type transistors and the current value of the current source is changed according to open or closed state of the switch.