always@smart
Full Member level 4
Hi All,
I'm a new guy for the Analog IC Design field. This is still the learning stage for me. RIght now i'm dealing with a project that is desiging Receiver part for the Optical Networking. I'm facing difficulties in the Photocurrent monitor circuit design as i couldn't find any sample of schematic or ciruitry from any books or from net. I already have designed the Transimpedance Amplifer and what i know is the IMON circuit input will be taken at the output of TIA. As my case i have the dummy tia in order to design the IMON. The IMON circut should detect the dc current of the current that going in to the TIA.
For example, if the input current to TIA is 0 ~ 15 uA (pp), than the IMON should detect the dc of 7.5uA and for other range of current.
Basically my idea was liek this.
when there is no input current at the TIA, the DC at output TIA is 1.319406 V. When there is the 0 ~ 15uA pp current goes to TIA, the output is 1.3138 V. So from here if I substract the DC of both this output and divide with the fixed resistor that is 700 ohm, i will get Idc at 8uA. and i did try the idc for other range of current and it works in the concept.
so, base on that i did develop a ciricut that is a comparator which will have 1 input with a fixed dc that is 1.319406 and another one with the output of the dummy TIA. so that whenever there is different range of current going in to TIA the output DC will vary and this will compare with the Vref of 1.319406 to generate a certain voltage at out comparator which will actually control the current. I did get the result but it is not getting accurate when the range of input current to is getting large. i did check all the biasing status of the CMOS, all were in saturation .. i don't know why.
I would apprecaite you guys if you can tell me what is wrong with that and how can i improve myh design in order to get the accurate I dc. Or if you guys have any other idea please help me to get it done.
Your cooperation is very much appreciated.
Thanks in advance,
Designer.
I'm a new guy for the Analog IC Design field. This is still the learning stage for me. RIght now i'm dealing with a project that is desiging Receiver part for the Optical Networking. I'm facing difficulties in the Photocurrent monitor circuit design as i couldn't find any sample of schematic or ciruitry from any books or from net. I already have designed the Transimpedance Amplifer and what i know is the IMON circuit input will be taken at the output of TIA. As my case i have the dummy tia in order to design the IMON. The IMON circut should detect the dc current of the current that going in to the TIA.
For example, if the input current to TIA is 0 ~ 15 uA (pp), than the IMON should detect the dc of 7.5uA and for other range of current.
Basically my idea was liek this.
when there is no input current at the TIA, the DC at output TIA is 1.319406 V. When there is the 0 ~ 15uA pp current goes to TIA, the output is 1.3138 V. So from here if I substract the DC of both this output and divide with the fixed resistor that is 700 ohm, i will get Idc at 8uA. and i did try the idc for other range of current and it works in the concept.
so, base on that i did develop a ciricut that is a comparator which will have 1 input with a fixed dc that is 1.319406 and another one with the output of the dummy TIA. so that whenever there is different range of current going in to TIA the output DC will vary and this will compare with the Vref of 1.319406 to generate a certain voltage at out comparator which will actually control the current. I did get the result but it is not getting accurate when the range of input current to is getting large. i did check all the biasing status of the CMOS, all were in saturation .. i don't know why.
I would apprecaite you guys if you can tell me what is wrong with that and how can i improve myh design in order to get the accurate I dc. Or if you guys have any other idea please help me to get it done.
Your cooperation is very much appreciated.
Thanks in advance,
Designer.