Hi all. Firstly, Love the site!
Now, the problem.
I have a complex RC problem similar to that found here:
http://www.allaboutcircuits.com/vol_1/chpt_16/7.html
except I have just R1, R2 and C. So it's even easier!
That page works out the time constant using the Thevenin equivalent circuit.
The time constant Im after however is different for the charge and discharge times. Ideally I want a capacitor that charges quickly and discharges slowly. Such as suggested here:
http://www.tpub.com/neets/book6/22e.htm
The capacitor filter.
I'm using a Schottky Barrier diode to half wave rectify a 1GHz signal which is being pulse modulated at 1kHz prf and 1µS pulse width. Currently I'm using 3(tore) = 1nS. So the capacitor will be charged to 95% in 3 time constants, however, I'm guessing that it will discharge really quickly too?
So what was suggested in the tpub site was to use a large capacitor and large load in parallel with the capacitor. This combination means the discharge time will be slow. But will that not mean the charge time will be slow also?
So just to summarise my questions:
1. Is it possible for a capacitor to have a fast charge time and slow discharge time?
2. Should I take my time constant value to be 0.333nS assuming 1GHz, or 0.333µS assuming 1µS pulse width.
3. (If question 1 = yes) Is it still accurate to convert this circuit into its Thevenin equivalent circuit?
Many Thanks
Dave
Now, the problem.
I have a complex RC problem similar to that found here:
http://www.allaboutcircuits.com/vol_1/chpt_16/7.html
except I have just R1, R2 and C. So it's even easier!
That page works out the time constant using the Thevenin equivalent circuit.
The time constant Im after however is different for the charge and discharge times. Ideally I want a capacitor that charges quickly and discharges slowly. Such as suggested here:
http://www.tpub.com/neets/book6/22e.htm
The capacitor filter.
I'm using a Schottky Barrier diode to half wave rectify a 1GHz signal which is being pulse modulated at 1kHz prf and 1µS pulse width. Currently I'm using 3(tore) = 1nS. So the capacitor will be charged to 95% in 3 time constants, however, I'm guessing that it will discharge really quickly too?
So what was suggested in the tpub site was to use a large capacitor and large load in parallel with the capacitor. This combination means the discharge time will be slow. But will that not mean the charge time will be slow also?
So just to summarise my questions:
1. Is it possible for a capacitor to have a fast charge time and slow discharge time?
2. Should I take my time constant value to be 0.333nS assuming 1GHz, or 0.333µS assuming 1µS pulse width.
3. (If question 1 = yes) Is it still accurate to convert this circuit into its Thevenin equivalent circuit?
Many Thanks
Dave