![]() | This article is rated C-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | ||||||||||
|
Hi, I don't understand the use of the original research or unverified claims tag here. This is everyday electronic engineering stuff that has been very well presented. Sfrahm 11:10, 26 October 2007 (UTC)
Good article. I hope you wont mind me trying to improve it by Wikifying and generally tidying it!-- Light current 00:33, 11 August 2006 (UTC)
I know it's a pain, but the word 'harmful' in your diagrams gives the wrong impression to readers. Maybe you could change it to 'unwanted' 8-)-- Light current 01:06, 11 August 2006 (UTC)
I would like to say that something is bad as it impedes, embarrasses, hampers, enervates the excitation input voltage when it strives to create a current. Also, I would like to say that the "bad thing" decreases, diminishes the effective (actual) current-creating voltage VRi = VIN - VR (in this arrangement, the resistor Ri actually acts as a voltage-to-current converter).
According to the considerations abov, we have to write, "...effectively modifies the actual current-creating voltage VRi..." By the way, can you "unearth" some simpler single word (like decrease, diminish etc.) instead the combination "effectively modify"?
I have inserted a para about the basic (non-electrical) idea of the passive version (similarly the active version). The idea is simple and well-known from our life: the impidements cause a pressure; so, in order to create a pressure, an impediment has to be applied.
I suppose to open a new page about passive current-to-voltage converter; IMO, it deserves attention. Then, we may remove the part about the passive version from this page to the new one.
I would like to come up for discussion the title. Actually, transimpedance amplifier and current-to-voltage converter are the same device. Only, I don't know why the first name is more frequently used although
So, I suggest to make 'Current-to-voltage converter' main page and 'Transimpedance amplifier' - redirected page. Circuit-fantasist 14:47, 12 August 2006 (UTC)
Actually, I would suggest going with the one that is more frequently used which is transimpedance. Also, to say that transimpedance is more meaningless would show a lack of understanding of an transimpedance amplifier. The gain of a transimpedance amplifier is ohms. Hence the name transimpedance. I can't tell if the trans is like transconductance in which that article says it stands for transfer but the same concept. Transconductance means the gain is going to be in Siemens. 155.33.109.148 22:47, 11 August 2007 (UTC)
I added the cleanup tag because of formatting and layout. It's rather choppy with very short paragraphs each with a heading. (Information looks good during a cursory look but the layout just makes it hard to follow). RJFJR 21:07, 21 September 2006 (UTC)
A C2VA is not always a TIA but a TIA is always a C2VA. Example: A resistor converts current to voltage, but its not a TIA. The TIA is an idealized model, just like the voltage opamp is an idealized model for simplified calculations. Steve110 20:31, 28 March 2007 (UTC)
I have swapped the two pages as the current-to-voltage converter name is more general than transimpedance amplifier one. Now, Current-to-voltage converter begins with the passive version and ends with the active one (see also Voltage-to-current converter).
I have moved also the discussion from this page to Current-to-voltage converter talk page.
Circuit-fantasist 12:06, 17 March 2007 (UTC)
I removed the redirection to Voltage-to-current converter and copied the most recent edits. Zen-in ( talk) 02:50, 1 December 2013 (UTC)
The pictures in this article have so many layers of annotation in multiple colors that they are extremely confusing. They look like the end result of a lecture, rather than an illustration for an article in an encyclopedia. A simpler set of schematics would be a valuable replacement. Kevin k ( talk) 17:08, 11 December 2012 (UTC)
Agreed. The pictures are of low quality, they are too verbose and they don't clearly explain the matter at hand. If someone can simplify the article & pictures - please do it!
Vaxquis ( talk) 21:04, 17 September 2013 (UTC)
+1 I am also in agreement. This definitely looks like this is notes from a lecture instead of an encyclopedia page. Reportingsjr ( talk) 18:40, 20 October 2013 (UTC)
I propose this page get a complete re-write and be renamed Transimpedance Amplifier. In Robert Pease's article he states "we used to call this a current-to-voltage converter,". The technical details on this page are weak and not well presented, despite the excessive verbosity and colorful plots. There is no discussion of compensation or the gain/BW tradeoff. Zen-in ( talk) 16:49, 2 November 2013 (UTC)
You are doing a great job. Consider this as a minor suggestion. I think a couple of your sentences are overly broad. First, “There is no cut and dry formula for calculating the capacitor value that works for all cases”. If all cases includes all types of amplifiers, loads, sources, applications, stability and bandwidth requirements then the statement is trivially true and applies to all amplifier design. Second “the iterative method required to optimize the value”. An iterative method can be used but there are many cases where those sufficiently skilled in algebra do not need to iterate. I have not looked at St Bob’s article, but I suspect he formed his opinions in the bad old days when opamps would go crazy with even a slight capacitive load and the spec sheet didn’t mention it. You were pretty much stuck with iterating the hardware (soldering real capacitors onto the breadboard to see what would happen). But in the modern era, opamp designers have recognized that there is often some capacitance hanging on the output. They have built in some tolerance to capacitive loads and they even spec it. If the series combination of Ci and Cf is less than the opamp’s specified capacitance driving capability then you can probably optimize the design on paper. I suppose you might iterate the paper design. Maybe that is what you meant. Still, I would replace “required” with something less compelling. Constant314 ( talk) 05:18, 5 December 2013 (UTC)
Copied from User talk:Constant314
I removed all this today because it is absolute unmitigated nonsense. There is no reason to ever want a "none (sic) inverting configuration" of a TIA since an inverting or non inverting follower is usually added. This was not an example of a non inverting amplifier anyway. Incrementally the circuit is still an inverting amplifier because the feedback is to the inverting terminal. So all that nonsense has been reverted. Zen-in ( talk) 16:51, 5 July 2015 (UTC)
It says, "In the circuit shown in Fig. 1 the photodiode is connected between ground and the inverting input of the op-amp. The other input of the op-amp is also connected to ground. This provides a low impedance load for the photodiode, which keeps the photodiode voltage low." As an ideal op-amp has infinite input impedance, how can connecting the photodiode between ground and the inverting input of the op-amp provide a low impedance load for the photodiode? Seems that it would provide a very high impedance load. The actual current path would be through the feedback resistor to the (ideally) zero impedance output, but the impedance of that path depends on Rf. Stevensrmiller ( talk) 19:55, 1 June 2016 (UTC)
This appears to be largely theoretical. There are no references for this idea. A single transistor stage does not provide enough gain for transimpedance to be realized. This recent addition should be removed. There are a few other issues with this page I want to address shortly. Zen-in ( talk) 14:55, 21 August 2018 (UTC)
In the literature known to me as well as on Wikipedia (see Electrical reactance) the reactance of a capacitor is a real quantity and not an imaginary. So the following equation from the article is wrong:
I propose that we change the word reactance in the text back to impedance and the X in the forumlas back to a Z. Do you agree? — Preceding unsigned comment added by Fvultier ( talk • contribs) 15:26, 23 August 2018 (UTC)
I think what Graeme is doing with the equation no one likes is to show the equivalence of the feedback across Rf and Ci as a frequency dependent resistive divider and as a frequency domain equation. If you just took the real part of both they would be the same. A Bode plot uses frequency domain equations (Laplace Transforms) so I agree the right formula there is Zen-in ( talk) 03:10, 25 August 2018 (UTC)
" The transimpedance amplifier presents a low impedance to the photodiode and isolates it from the output voltage of the operational amplifier. In its simplest form a transimpedance amplifier has just a large-valued feedback resistor, Rf. The gain of the amplifier is set by this resistor and has a value of −Rf (because the amplifier is in an inverting configuration). There are several different configurations of transimpedance amplifiers, each suited to a particular application. The one factor they all have in common is the requirement to convert the low-level current to a voltage.
The gain, bandwidth, as well as current and voltage offsets, change with different types of sensors, requiring different configurations of transimpedance amplifiers. "
This text is already present in the introduction of the article. In case that it is voluntary, i'm not deleting it myself. The two sources [3] and [5] are also the same. — Preceding unsigned comment added by The quantum panda ( talk • contribs) 10:23, 29 April 2019 (UTC)
![]() | This article is rated C-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | ||||||||||
|
Hi, I don't understand the use of the original research or unverified claims tag here. This is everyday electronic engineering stuff that has been very well presented. Sfrahm 11:10, 26 October 2007 (UTC)
Good article. I hope you wont mind me trying to improve it by Wikifying and generally tidying it!-- Light current 00:33, 11 August 2006 (UTC)
I know it's a pain, but the word 'harmful' in your diagrams gives the wrong impression to readers. Maybe you could change it to 'unwanted' 8-)-- Light current 01:06, 11 August 2006 (UTC)
I would like to say that something is bad as it impedes, embarrasses, hampers, enervates the excitation input voltage when it strives to create a current. Also, I would like to say that the "bad thing" decreases, diminishes the effective (actual) current-creating voltage VRi = VIN - VR (in this arrangement, the resistor Ri actually acts as a voltage-to-current converter).
According to the considerations abov, we have to write, "...effectively modifies the actual current-creating voltage VRi..." By the way, can you "unearth" some simpler single word (like decrease, diminish etc.) instead the combination "effectively modify"?
I have inserted a para about the basic (non-electrical) idea of the passive version (similarly the active version). The idea is simple and well-known from our life: the impidements cause a pressure; so, in order to create a pressure, an impediment has to be applied.
I suppose to open a new page about passive current-to-voltage converter; IMO, it deserves attention. Then, we may remove the part about the passive version from this page to the new one.
I would like to come up for discussion the title. Actually, transimpedance amplifier and current-to-voltage converter are the same device. Only, I don't know why the first name is more frequently used although
So, I suggest to make 'Current-to-voltage converter' main page and 'Transimpedance amplifier' - redirected page. Circuit-fantasist 14:47, 12 August 2006 (UTC)
Actually, I would suggest going with the one that is more frequently used which is transimpedance. Also, to say that transimpedance is more meaningless would show a lack of understanding of an transimpedance amplifier. The gain of a transimpedance amplifier is ohms. Hence the name transimpedance. I can't tell if the trans is like transconductance in which that article says it stands for transfer but the same concept. Transconductance means the gain is going to be in Siemens. 155.33.109.148 22:47, 11 August 2007 (UTC)
I added the cleanup tag because of formatting and layout. It's rather choppy with very short paragraphs each with a heading. (Information looks good during a cursory look but the layout just makes it hard to follow). RJFJR 21:07, 21 September 2006 (UTC)
A C2VA is not always a TIA but a TIA is always a C2VA. Example: A resistor converts current to voltage, but its not a TIA. The TIA is an idealized model, just like the voltage opamp is an idealized model for simplified calculations. Steve110 20:31, 28 March 2007 (UTC)
I have swapped the two pages as the current-to-voltage converter name is more general than transimpedance amplifier one. Now, Current-to-voltage converter begins with the passive version and ends with the active one (see also Voltage-to-current converter).
I have moved also the discussion from this page to Current-to-voltage converter talk page.
Circuit-fantasist 12:06, 17 March 2007 (UTC)
I removed the redirection to Voltage-to-current converter and copied the most recent edits. Zen-in ( talk) 02:50, 1 December 2013 (UTC)
The pictures in this article have so many layers of annotation in multiple colors that they are extremely confusing. They look like the end result of a lecture, rather than an illustration for an article in an encyclopedia. A simpler set of schematics would be a valuable replacement. Kevin k ( talk) 17:08, 11 December 2012 (UTC)
Agreed. The pictures are of low quality, they are too verbose and they don't clearly explain the matter at hand. If someone can simplify the article & pictures - please do it!
Vaxquis ( talk) 21:04, 17 September 2013 (UTC)
+1 I am also in agreement. This definitely looks like this is notes from a lecture instead of an encyclopedia page. Reportingsjr ( talk) 18:40, 20 October 2013 (UTC)
I propose this page get a complete re-write and be renamed Transimpedance Amplifier. In Robert Pease's article he states "we used to call this a current-to-voltage converter,". The technical details on this page are weak and not well presented, despite the excessive verbosity and colorful plots. There is no discussion of compensation or the gain/BW tradeoff. Zen-in ( talk) 16:49, 2 November 2013 (UTC)
You are doing a great job. Consider this as a minor suggestion. I think a couple of your sentences are overly broad. First, “There is no cut and dry formula for calculating the capacitor value that works for all cases”. If all cases includes all types of amplifiers, loads, sources, applications, stability and bandwidth requirements then the statement is trivially true and applies to all amplifier design. Second “the iterative method required to optimize the value”. An iterative method can be used but there are many cases where those sufficiently skilled in algebra do not need to iterate. I have not looked at St Bob’s article, but I suspect he formed his opinions in the bad old days when opamps would go crazy with even a slight capacitive load and the spec sheet didn’t mention it. You were pretty much stuck with iterating the hardware (soldering real capacitors onto the breadboard to see what would happen). But in the modern era, opamp designers have recognized that there is often some capacitance hanging on the output. They have built in some tolerance to capacitive loads and they even spec it. If the series combination of Ci and Cf is less than the opamp’s specified capacitance driving capability then you can probably optimize the design on paper. I suppose you might iterate the paper design. Maybe that is what you meant. Still, I would replace “required” with something less compelling. Constant314 ( talk) 05:18, 5 December 2013 (UTC)
Copied from User talk:Constant314
I removed all this today because it is absolute unmitigated nonsense. There is no reason to ever want a "none (sic) inverting configuration" of a TIA since an inverting or non inverting follower is usually added. This was not an example of a non inverting amplifier anyway. Incrementally the circuit is still an inverting amplifier because the feedback is to the inverting terminal. So all that nonsense has been reverted. Zen-in ( talk) 16:51, 5 July 2015 (UTC)
It says, "In the circuit shown in Fig. 1 the photodiode is connected between ground and the inverting input of the op-amp. The other input of the op-amp is also connected to ground. This provides a low impedance load for the photodiode, which keeps the photodiode voltage low." As an ideal op-amp has infinite input impedance, how can connecting the photodiode between ground and the inverting input of the op-amp provide a low impedance load for the photodiode? Seems that it would provide a very high impedance load. The actual current path would be through the feedback resistor to the (ideally) zero impedance output, but the impedance of that path depends on Rf. Stevensrmiller ( talk) 19:55, 1 June 2016 (UTC)
This appears to be largely theoretical. There are no references for this idea. A single transistor stage does not provide enough gain for transimpedance to be realized. This recent addition should be removed. There are a few other issues with this page I want to address shortly. Zen-in ( talk) 14:55, 21 August 2018 (UTC)
In the literature known to me as well as on Wikipedia (see Electrical reactance) the reactance of a capacitor is a real quantity and not an imaginary. So the following equation from the article is wrong:
I propose that we change the word reactance in the text back to impedance and the X in the forumlas back to a Z. Do you agree? — Preceding unsigned comment added by Fvultier ( talk • contribs) 15:26, 23 August 2018 (UTC)
I think what Graeme is doing with the equation no one likes is to show the equivalence of the feedback across Rf and Ci as a frequency dependent resistive divider and as a frequency domain equation. If you just took the real part of both they would be the same. A Bode plot uses frequency domain equations (Laplace Transforms) so I agree the right formula there is Zen-in ( talk) 03:10, 25 August 2018 (UTC)
" The transimpedance amplifier presents a low impedance to the photodiode and isolates it from the output voltage of the operational amplifier. In its simplest form a transimpedance amplifier has just a large-valued feedback resistor, Rf. The gain of the amplifier is set by this resistor and has a value of −Rf (because the amplifier is in an inverting configuration). There are several different configurations of transimpedance amplifiers, each suited to a particular application. The one factor they all have in common is the requirement to convert the low-level current to a voltage.
The gain, bandwidth, as well as current and voltage offsets, change with different types of sensors, requiring different configurations of transimpedance amplifiers. "
This text is already present in the introduction of the article. In case that it is voluntary, i'm not deleting it myself. The two sources [3] and [5] are also the same. — Preceding unsigned comment added by The quantum panda ( talk • contribs) 10:23, 29 April 2019 (UTC)