Transimpedance circuit

Patent metadata

Field	Value
Publication number	US-9837969-B2
Application number	US-201514819186-A
Country	US
Kind code	B2
Filing date	Aug 5, 2015
Priority date	Mar 9, 2015
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

According to one embodiment, a transimpedance circuit includes: a transimpedance amplifier that converts a current signal into a voltage signal, a reference voltage generating circuit that generates a reference voltage signal, and a comparator that generates a pulse signal corresponding to the current signal in accordance with a voltage level of the voltage signal and a voltage level of the reference voltage signal. The transimpedance amplifier includes a first transistor that amplifies the current signal, a voltage converter that converts the current signal into a voltage signal, and a bypass circuit that allows the current signal to be bypassed when the current signal which flows through a control terminal of the first transistor exceeds a predetermined value.

First claim

What is claimed is:

1. A transimpedance circuit, comprising:
a first transistor connected between a first voltage terminal and a second voltage terminal and having a control electrode connected to a current signal input node;
a second transistor connected between a current source and the second voltage terminal and having a control electrode connected to a first electrode of the first transistor;
a third transistor connected between the first voltage terminal and a voltage signal node and having a control electrode connected to a second electrode of the second transistor;
a voltage conversion circuit connected between the current signal input node and the voltage signal output node; and
a bypass circuit connected between the current signal input node and the control electrode of the third transistor, the bypass circuit comprising a diode and configured to provide a conductance pathway between the current signal input node and the control electrode of the third transistor when a level of a current signal at the current signal input node exceeds a predetermined value.

2. The transimpedance circuit according to claim 1 , wherein the diode is a diode-connected transistor.

3. The transimpedance circuit according to claim 2 , wherein the diode-connected transistor is a metal-oxide-semiconductor field effect transistor.

4. The transimpedance circuit according to claim 1 , wherein
the bypass circuit further comprises a resistor connected in series with the diode, and
the diode is a diode-connected bipolar transistor.

5. The transimpedance circuit according to claim 1 , further comprising:
a fourth transistor connected between the control electrode of the third transistor and the second electrode of the second transistor, the fourth transistor being a diode-connected transistor.

6. The transimpedance circuit according to claim 1 , further comprising:
an inverting amplifier connected between the voltage signal output node and a second voltage signal output node and configured to output an inverted voltage signal corresponding to a current signal received at the current signal input node.

7. The transimpedance circuit according to claim 1 , wherein the first, second, and third transistor are bipolar transistors.

8. The transimpedance circuit according to claim 1 , wherein the first, second, and third transistors are metal-oxide-semiconductor field effect transistors.

Assignees

• Toshiba Kk

Inventors

• Tsunetsugu Yukio

Classifications

• H03F2200/78

  A comparator being used in a controlling circuit of an amplifier · CPC title

• H03F1/3205 Primary

  in field-effect transistor amplifiers · CPC title

• H03F3/082

  with FET's (H03F3/085 takes precedence) · CPC title

• H03F3/3435

  using Darlington amplifiers · CPC title

• H03F3/08

  controlled by light · CPC title