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Transimpedance Amplifier (TIA) is a device which is used to convert the input current signal to a voltage signal. In basic, the TIA will be attached to a photodiode. In the optical communications, in the receiver part, the light will be detected and converted to current signal by photodiode. Then this current will be converted to voltage by the so called transimpedance amplifier. There are many type of TIA architecture which u can get by doing some research on it.
About the unit dBΩ, see you are converting the current to voltage, so your amplifier gain is R= V/I which is Ω. So, when you convert to 20 Log V/I, your last unit will be dBΩ.
1. Jitter
2. If there is any mismatch in inpedance, the eye diagram will more close.
3. From the TIA eyediagarm, able to know how good the signal to transfer
liming amplifier.
In optical communications, the signals are transferred in NRZ coding which is basically on the matter of "1" or "0" switching. So, in order to measure the quality of this signal, some measurement is used to detect it which is called "eye-diagram" tool. Basically eyediagram, is divided into two, i) optical eye-diagram, ii) electrical eyediagram. Optical means, when u measure the signal from the transmitter (TX), and electrical means you meaure the signal after the Receiver (RX) which goes in to CDR(clock and data recovery).
So, basically by using this eye-diagram measurement we can know the noise induced within the circuit which may caused by the electronic devices, PCB traces, wire-bonds, mismatches and so on. Since the NRZ signal is generated randomly, and when there is long runs of bits 1s & 0s, so it will induce different crossing points in the signals, so by using the eye-diagram, we can astually measure the different of the crossings of the signal through jitter as well.
Eye-diagram, is measured through the entire Tx or Rx system not only at TIA.
hi all,
I am a beginner in analog IC design...I have a question...in making TIA for optical Rx, does this involve issues in RF circuits as in LNA..? please clarify, and point out some resources for TIA design.
thnx
hi all,
I am a beginner in analog IC design...I have a question...in making TIA for optical Rx, does this involve issues in RF circuits as in LNA..? please clarify, and point out some resources for TIA design.
thnx
TIA is a very important block in Optical Receiver System. Why it is important? Yes,
as a frond stage in the optical RX system, first at all it has to reduce the noise/minimize noise that going in to the next block. Next in order to increase the sensitivity, it has very much effect from noise, thus lowering down noise will increase sensitivity. Basically you need a TIA with a high gain, thus it can amplify any small signal (from high sensitivity) for the Limiting amplifier to process the signal without attenuation or degradation from the further noise. This tia need to have very low input reffered noise. Pls refer to journals on how to improve this input referred noise based on what type of configuration is neccesary to meet all the design spesification. Hope this helps you.
You can convert current to voltage with simple resistor and you will have Vout=Rf*Id.
For noise, and signal gain it is good to have as large as possible Rf, but then you have problem with small bandwidth 1/RfCd, where Cd is photodiode capacity.
In the case of TIA, with gain A, your BW is A+1 times higher because photodiode see (1+A)*smaller resistance (Miller effect), while signal gain is the same (Vout=Rf*Id).
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