Feedback type pre-amplifier
AssigneeHitachi, Ltd.
InventorRyoji Takeyari
Life of this patent
Estimating the term…
Abstract
A pre-amplifier disclosed in which low noise at the time of small input and linear amplification at the time of large input are compatible. In a pre-amplifier, such compatibility can be realized by constituting a current mirror circuit, with respect to a current of a first stage transistor in a transimpedance portion, by a by-passing transistor which is provided at an input side of the pre-amplifier. In such a configuration, by making a by-pass current flow proportionally to an input instantaneous current at the time of a large input, the transimpedance can be made small equivalently to thereby widen the dynamic range.
Claims16
A pre-amplifier comprising:
- input means for receiving a current signal;
- amplifying means including a transistor for amplifying the received current signal;
- a control current source connected to said input means for by-passing the received current signal;
- current detecting means connected as a component of said amplifying means;
- and
- a resistor component arranged in a feedback connection between said input means and an output portion,
- wherein said current detecting means is arranged to effect control of said control current source.
A pre-amplifier comprising:
- input means for receiving a current signal;
- amplifying means including at least one transistor for amplifying the received current signal;
- current detecting means connected as a component of said amplifying means;
- a resistor component arranged in a feedback connection between said input means and an output portion;
- a control current source electrically connected to said input means, said control current source being controlled by said current detecting means;
- and
- a current dividing circuit connected to said control current source, at least one output of said current dividing circuit being connected to an input of said pre-amplifier.
A pre-amplifier comprising:
- input means for receiving a current signal;
- amplifying means including at lest one transistor for amplifying the received current signal;
- current detecting means connected as a component of said amplifying means;
- a resistor component arranged in a feedback connection between said input means and an output portion;
- a control current source electrically connected to said input means, said control current source being controlled by said current detecting means;
- a current dividing circuit connected to said control current source, at least one output of said current dividing circuit being connected to an input of said pre-amplifier;
- and
- detecting means which detects an average output voltage of said pre-amplifier,
- wherein said current dividing circuit is arranged to be responsive to an average output voltage of said pre-amplifier in a manner which maintains a difference between the detected average output voltage and a reference potential at a predetermined value.
An optical receiver comprising control means connected to a pre-amplifier for controlling a current distribution ratio of said pre-amplifier in correspondence to power of an optical signal inputted to said pre-amplifier, wherein said pre-amplifier comprises:
- input means for receiving a current signal;
- amplifying means including at least one transistor for amplifying the received current signal;
- current detecting means connected as a component of said amplifying means;
- a resistor component arranged in a feedback connection between said input means and an output portion of said pre-amplifier;
- a control current source coupled to said input means, said control current source being controlled by said current detecting means;
- and
- a current dividing circuit connected to said control current source, at least one output of said current dividing circuit being connected to an input of said pre-amplifier.
A pre-amplifier comprising:
- input means for receiving a current signal;
- amplifying means including at least one transistor for amplifying the received current signal;
- current detecting means connected as a component of said amplifying means;
- a resistor component arranged in a feedback connection between said input means and an output of said pre-amplifier;
- a control current source electrically connected to said input means, said control current source being controlled by said current detecting means;
- a current dividing circuit connected to said control current source, at least one output of said current dividing circuit being connected to an input of said pre-amplifier;
- a low-pass filter which receives output signals of said pre-amplifier and effects an averaging thereof by the low-pass filter action;
- and
- an integrator which compares detection of the average output potentials, at an output of said low-pass filter, with a reference potential,
- wherein said current dividing circuit is controlled in accordance with an average output voltage of said pre-amplifier.
A pre-amplifier comprising:
- an input for receiving a current signal and an output for providing an output signal;
- an amplifying circuit including a transistor having a control terminal supplied with the current signal received at said input;
- a control current source electrically connected to said input means for by-passing the received current signal;
- a current detector arranged as a component of said amplifying circuit;
- and
- a resistor component arranged in a feedback connection between the input and output of said pre-amplifier,
- wherein said current detector is arranged to effect control of said control current source.
An optical receiver comprising control means connected to a pre-amplifier for controlling a current distribution ratio of said pre-amplifier in correspondence to power of an optical signal inputted to said pre-amplifier, wherein said pre-amplifier comprises:
- an input for receiving a current signal and an output for providing an output signal;
- an amplifier circuit including at least one transistor for amplifying the received current signal;
- a current detector arranged as a component of said amplifier circuit;
- a resistor component arranged in a feedback connection between the input and output of said pre-amplifier;
- a control current source coupled to said input, said control current source being controlled by said current detector;
- and
- a current dividing circuit connected to said control current source, at least one output of said current dividing circuit being connected to an input of said pre-amplifier.
Dependencies are inferred from the claim text.