digital-brain/content/zettels/transimpedance_amplifiers.md

+++
title = "Transimpedance Amplifiers"
author = ["Dehaeze Thomas"]
draft = false
category = "equipment"
+++

Tags
: [Electronics]({{< relref "electronics.md" >}})


## Description {#description}

A transimpedance amplifier is a "current to voltage converter" and is also named a current controlled voltage source.

It is generally used to interface a sensor which outputs a current proportional to the measurement parameter ([Quadrant Photodiodes]({{< relref "quadrant_photodiodes.md" >}}) for instance).


## Basic Circuit {#basic-circuit}

A basic transimpedance amplifier circuit is shown in Figure [1](#figure--fig:transimpedance-amplifier-schematic).

It produces an output voltage \\(V\_{\text{out}}\\) proportional to the input current \\(I\_{\text{sig}}\\):

\begin{equation}
\boxed{V\_{\text{out}} = -I\_{\text{sig}} R\_f}
\end{equation}

The gain of the amplifier is simply \\(-R\_f\\) in [V/A].

The feedback resistor creates a Johnson noise that corresponds to a current noise:

\begin{equation}
i\_{n} = \sqrt{4kT/R\_f} \quad [A/\sqrt{Hz}]
\end{equation}

This is usually larger than the amplifier input current noise.

<a id="figure--fig:transimpedance-amplifier-schematic"></a>

{{< figure src="/ox-hugo/transimpedance_amplifier_schematic.png" caption="<span class=\"figure-number\">Figure 1: </span>Transimpedance Amplifier; Current in, Voltage out" >}}

More information about transimpedance can be found in [The art of electronics - third edition]({{< relref "horowitz15_art_of_elect_third_edition.md" >}}), chapter 8.11.4, especially on the trade-off between gain, noise and bandwidth.

See [this](https://www.hardware-x.com/article/S2468-0672(21)00062-6/fulltext) open hardware design.


## Manufacturers {#manufacturers}

| Manufacturers                                                                                              | Country |
|------------------------------------------------------------------------------------------------------------|---------|
| [Kistler](https://www.kistler.com/fr/produits/composants/conditionnement-de-signal/)                       | Swiss   |
| [MMF](https://www.mmf.de/signal_conditioners.htm)                                                          | Germany |
| [Femto](https://www.femto.de/en/products/current-amplifiers.html)                                          | Germany |
| [FMB Oxford](https://www.fmb-oxford.com/products/controls-2/control-modules/i404-quad-current-integrator/) | UK      |
| [Thorlabs](https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=7083)                                 | UK      |
| [Koheron](https://www.koheron.com/photonics/pd4q-4-quadrant-photodetector)                                 | France  |
| [SRS](https://www.thinksrs.com/products/sr570.html)                                                        |         |
| [Basel Precision Instruments](https://www.baspi.ch/low-noise-high-stab-itov-conv)                          | Swiss   |


## Bibliography {#bibliography}

<style>.csl-entry{text-indent: -1.5em; margin-left: 1.5em;}</style><div class="csl-bib-body">
</div>
Update Content - 2020-10-19 2020-10-19 10:13:36 +02:00			`+++`
			`title = "Transimpedance Amplifiers"`
Update Content - 2022-03-15 2022-03-15 16:40:48 +01:00			`author = ["Dehaeze Thomas"]`
Update Content - 2020-10-19 2020-10-19 10:13:36 +02:00			`draft = false`
Update many files PhDthesis were categorized as articles. Add "fron matter" to specify zettels category 2021-09-29 22:30:09 +02:00			`category = "equipment"`
Update Content - 2020-10-19 2020-10-19 10:13:36 +02:00			`+++`

			`Tags`
Update Content - 2022-03-15 2022-03-15 16:40:48 +01:00			`: [Electronics]({{< relref "electronics.md" >}})`
Update Content - 2020-10-19 2020-10-19 10:13:36 +02:00

			`## Description {#description}`

			`A transimpedance amplifier is a "current to voltage converter" and is also named a current controlled voltage source.`

Update Content - 2022-03-30 2022-03-30 09:29:44 +02:00			`It is generally used to interface a sensor which outputs a current proportional to the measurement parameter ([Quadrant Photodiodes]({{< relref "quadrant_photodiodes.md" >}}) for instance).`
Update Content - 2020-10-19 2020-10-19 10:13:36 +02:00

Update Content - 2022-10-27 2022-10-27 17:57:43 +02:00			`## Basic Circuit {#basic-circuit}`

			`A basic transimpedance amplifier circuit is shown in Figure [1](#figure--fig:transimpedance-amplifier-schematic).`

			`It produces an output voltage \\(V\_{\text{out}}\\) proportional to the input current \\(I\_{\text{sig}}\\):`

			`\begin{equation}`
			`\boxed{V\_{\text{out}} = -I\_{\text{sig}} R\_f}`
			`\end{equation}`

			`The gain of the amplifier is simply \\(-R\_f\\) in [V/A].`

			`The feedback resistor creates a Johnson noise that corresponds to a current noise:`

			`\begin{equation}`
			`i\_{n} = \sqrt{4kT/R\_f} \quad [A/\sqrt{Hz}]`
			`\end{equation}`

			`This is usually larger than the amplifier input current noise.`

			`<a id="figure--fig:transimpedance-amplifier-schematic"></a>`

			`{{< figure src="/ox-hugo/transimpedance_amplifier_schematic.png" caption="<span class=\"figure-number\">Figure 1: </span>Transimpedance Amplifier; Current in, Voltage out" >}}`

			`More information about transimpedance can be found in [The art of electronics - third edition]({{< relref "horowitz15_art_of_elect_third_edition.md" >}}), chapter 8.11.4, especially on the trade-off between gain, noise and bandwidth.`

			`See [this](https://www.hardware-x.com/article/S2468-0672(21)00062-6/fulltext) open hardware design.`


Update Content - 2020-10-19 2020-10-19 10:13:36 +02:00			`## Manufacturers {#manufacturers}`

Update Content - 2021-03-14 2021-03-14 16:00:24 +01:00			`\| Manufacturers \| Country \|`
			`\|------------------------------------------------------------------------------------------------------------\|---------\|`
			`\| [Kistler](https://www.kistler.com/fr/produits/composants/conditionnement-de-signal/) \| Swiss \|`
Update Content - 2022-03-15 2022-03-15 16:40:48 +01:00			`\| [MMF](https://www.mmf.de/signal_conditioners.htm) \| Germany \|`
Update Content - 2021-03-14 2021-03-14 16:00:24 +01:00			`\| [Femto](https://www.femto.de/en/products/current-amplifiers.html) \| Germany \|`
			`\| [FMB Oxford](https://www.fmb-oxford.com/products/controls-2/control-modules/i404-quad-current-integrator/) \| UK \|`
Update Content - 2022-10-27 2022-10-27 17:57:43 +02:00			`\| [Thorlabs](https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=7083) \| UK \|`
Update Content - 2023-04-15 2023-04-15 12:02:29 +02:00			`\| [Koheron](https://www.koheron.com/photonics/pd4q-4-quadrant-photodetector) \| France \|`
Update Content - 2023-11-03 2023-11-03 09:41:22 +01:00			`\| [SRS](https://www.thinksrs.com/products/sr570.html) \| \|`
Update Content - 2024-05-21 2024-05-21 20:32:38 +02:00			`\| [Basel Precision Instruments](https://www.baspi.ch/low-noise-high-stab-itov-conv) \| Swiss \|`
Update Content - 2022-03-15 2022-03-15 16:40:48 +01:00

			`## Bibliography {#bibliography}`

			`<style>.csl-entry{text-indent: -1.5em; margin-left: 1.5em;}</style><div class="csl-bib-body">`
			`</div>`