Conversion of power consumption from mW to pJ/pulse

[hanen88]

Hi,
I have designed an UWB transmiiter that emits pulses, the overall power consumtion is 46 mW. I would lik to convert this power into pJ/pulse, what can i do taking account that the pulse width is 3 ns and the pulse repetition rate is 20 ns.
Sincerly.

 

[KlausST]

Hi,

1 J = 1 Ws

For ease of understanding let´s decide to set the time to 1s.

Then we have 46mW (independent of time) = 46mJ/s = 46,000uJ/s = 46,000,000nJ/s = 46,000,000,000pJ/s
and we have 1 / 20ns/pulse = 50,000,000 pulses/s

Now divide: 46,000,000,000pJ/s / 50,000,000pulse/s =(cut 7x "0" away on each side) = 4,600/5 pJ/pulse = 920pJ/pulse
Note: always use the correct "units" and if everything is calculated correctly: the units must match.

This wasn´t that difficult, I think.

The 3ns pulse width is irrelevant for this.

Klaus

 

[hanen88]

I don't understand this conversion ''Then we have 46mW (independent of time) = 46mJ/s = 46,000uJ/s = 46,000,000nJ/s = 46,000,000,000pJ/s''

When i have 46 mw and pulse width is 3 ns , the power consumption will be Pdc=138 pJ/s
Because we have PRP=20 ns, the PRF=50 MHz donc Pdc=138/50 pJ/s=2.76 pJ/s
Is it correct

 

[KlausST]

Hi,

I don't understand this conversion ''Then we have 46mW (independent of time) = 46mJ/s = 46,000uJ/s = 46,000,000nJ/s = 46,000,000,000pJ/s''

There are just two conversions: Which one you don´t understand?
* W --> J/s
or
* m --> u --> n --> p
?

*****
as already said:

The 3ns pulse width is irrelevant for this.

Klaus