US 12,451,842 B2Granted

Variable transimpedance amplifier for low power, high dynamic range, high data rate linear

AssigneeSemtech Corporation

InventorGurpreet Singh Bhullar

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Abstract

A variable transimpedance amplifier may include first and second amplifiers. Each of the first and second amplifiers may include a transistor amplifier with a feedback resistor and a capacitor. The output node of the first amplifier may be an output node of the variable transimpedance amplifier. The output node of the second amplifier is not part of the output node of the variable transimpedance amplifier. The open loop gains of the transistor amplifiers may be variable, but the feedback resistor values can be fixed. The transimpedance may be determined by the feedback resistors and a scaling factor proportional to ratio of open loop gains. The transistor amplifiers may share an input transistor. The configuration can provide a high dynamic range of variable transimpedance that is stable over process and operating condition variations, minimize input capacitance loading and noise contribution to small input signals.

Claims22

Dependent claims

A variable transimpedance amplifier, comprising:

a first amplifier comprising:
a first bipolar junction transistor amplifier;
a first resistor connected in parallel with the first bipolar junction transistor amplifier;
and
a first capacitor connected in parallel with the first bipolar junction transistor amplifier and the first resistor;
and
a second amplifier comprising:
a second bipolar junction transistor amplifier;
a second resistor connected in parallel with the second bipolar junction transistor amplifier;
and
a second capacitor connected in parallel with the second bipolar junction transistor amplifier and the second resistor;
wherein:
the first amplifier and the second amplifier are connected to an input node of the variable transimpedance amplifier in parallel;
a first output node of the first amplifier is an output node of the variable transimpedance amplifier, the output node configured to drive a circuit subsequent to the variable transimpedance amplifier;
and
a second output node of the second amplifier is configured to be outside of the output node of the variable transimpedance amplifier, the second output node configured to be excluded from driving the circuit subsequent to the variable transimpedance amplifier.

13 more elements

A variable transimpedance amplifier, comprising:

a primary amplifier comprising:
a primary transistor amplifier;
a primary resistor connected in parallel with the primary transistor amplifier;
and
a primary capacitor connected in parallel with the primary transistor amplifier and the primary resistor;
and
one or more secondary amplifiers, each comprising:
a secondary transistor amplifier;
a secondary resistor connected in parallel with the secondary transistor amplifier;
and
a secondary capacitor connected in parallel with the secondary transistor amplifier and the secondary resistor;
wherein:
the primary amplifier and the one or more secondary amplifiers are connected to an input node of the variable transimpedance amplifier in parallel;
a primary output node of the primary amplifier is an output node of the variable transimpedance amplifier, the output node configured to drive a circuit subsequent to the variable transimpedance amplifier;
and
secondary output nodes of the one or more secondary amplifiers are configured to be outside of the output node of the variable transimpedance amplifier, the secondary output nodes configured to be excluded from driving the circuit subsequent to the variable transimpedance amplifier.

13 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/079,840Filed 12 Dec 2022
Published: US 2024/0195360 A113 Jun 2024
Granted: 21 Oct 2025
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

H03F 1/0211
In transistor amplifiers: with control of the supply voltage or current
H03F 3/087
Controlled by light: with IC amplifier blocks
H03F 1/22
Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements: by use of cascode coupling, i.e.…
H03F 3/211
With semiconductor devices only: using a combination of several amplifiers