Recent content by thavamaran

Hi guys, I am currently writing-up my PhD thesis, research topic is in the area 4G LTE and optical fibre communication integration, from not very well reputed university in UK. I have published about 8 papers, where 3 of it are IEEE journals. I have another 3 under review, with one of it is...

Hi, I am designing an RF link. Before my spectrum analyzer, I have an RF low noise amp with a NF of 2.5 dB. Without this amplifier, my error vector magnitude or error rate is 2.1%, after an amplifier it goes down to 0.7%. My question is, the receiving signal will have its own SNR and with...

Hi Berkeman. Do you have any example of a switched current source. Its just me working in this project. Cheers.

Most IC's that I have seen doesn't operate in DC. Its for biasing a laser. We have to supply a certain amount of current, say 40 mA to drive it. I just want to switch it off at some time interval. Do you have suggestion. Thanks for your reply.

Hi guys. I recently posted to discuss on switching signals. I have resolved that. Now, I am trying to switch a DC voltage/current. Say I am supply a DC stable bias current of about 40 mA. If I want to switch it off at certain time interval, maximum of 40 us. Which means, the maximum...

Thanks very much for your reply! May I ask what you meant by finite switching time? At the moment, there is no requirements on on and off resistance, may I also ask why I need this? Current rating would be from 40 mA to 150 mA. Do you have any reference circuits or model that will...

Hi guys, I am Thava. I am working in optical communication. Currently I want to design a circuit to turn of couple of inputs to my laser. Say I have a supply of 5V to two pins of the laser, anode and cathode (pin 1 and pin 2). And then a bias current to another pin (pin 3). At some...

Hi guys, I have a problem in understanding LTE. LTE is the long term evolution 4G technology. The LTE requirement is 100 Mbps with 1.3, 2.5, 5, 10, 15 and 20 MHz for 128, 256, 512, 1024, 1536 and 2048 subcarriers. Each bandwidth corresponds to each number of subcarriers. My problem here...

Hi guys, I am trying to implement Analogue FDM on top of my single carrier modulation (eg: QAM and QPSK) of Multi carrier modulation (eg: OFDM). For an example, I have two different pair of I and Q channels, where first pair is upconverted at 2.2 GHz and the next pair at say 2.7 GHz and them MUX...

Hi guys, I am eager to find out about our spectrum usage. Cause I am working on LTE and it uses either 2.7 GHz or 900 MHz, range of UHF. Do anyone have a link, paper or book referring to various applications spectrum usage, like all other mobile communication or defense spectrum usage. Thank...

But mine works in 2.7 GHz. Is that still possible?

well, I want to combine them as in multiplexing them to combine bit rate and enhance my spectral efficiency and transmit them in optical. What do you meant by power combiner? Thanks for the reply.

Hi guys, I'm currently generating OFDM signal and send it to DAC and then upconvert them to 1 GHz carrier signal. I want to multiplex several of them, like say I upconvert them to 1 GHz, 800 MHz, 1.2 GHz, which represents 3 different signals, then multiplex them together using FDM, is it...

Hi guys, I have this question, I know in OFDM system, when you upconvert the signal with certain carrier frequency with certain sampling frequency and when you downconvert it, if the carrier frequency is same, but the sampling is not, then you will have a sampling frequency offset and that will...

Hi there, thanks for your reply. But GMSK is for digital modulation. After upconverting my signal to 1 GHz, it will be analogue then. For an instance, say I have a signal with carrier frequency of 1 GHz and 1.2 GHz, can I use FDM to multiplex them? Thank you!