2014 Exam Flashcards
(9 cards)
1
Q
Types of Source Termination (3)
A
On-Die
- o/p imp. of buffer to be constant over the op. range + close to Z0
- ideal soln has no extra components but hard to achieve as o/p imp. difficult to control
Series Source
- Add resistor w/ o/p buffer, Zs + RS = Z0
- Works well if Rs >> o/p imp
- uncertainty in Rs if small
- resistors add cost + take up space
Parallel Load Termination
- add a resistor in parallel w/ o/p buffer to remove reflections
- extra power dissipation in the extra resistor as well as cost + space
2
Q
How does USB control reflections (4)
A
- Terminations vary according to speed grade
- Downstream facing host / hub signals are pulled down by 15kOhm for all speeds
- A low speed device has a 1.5kOhm pull-up resistor connected to the D- signal
- A full speed device is terminated by a 1.5kOhm resistor connected to D+
3
Q
What is the Mode of a T.L
A
a field pattern which remains unchanged as it propagates
4
Q
Odd Mode Propagation Characteristics (3)
A
- lines are out of phase, equal signal mag. + 180 degrees out of phase
- eff. cap will increase by 2x M.C
- eff. ind will decrease by M.I
5
Q
Even Mode Propagation Characteristics (3)
A
- lines are driven in phae (eq. mag. + phase)
- eff. cap will decrease by 2x M.C
- eff. ind. will increase by M.I
6
Q
Pertubation Definition
A
a deviation of a system / moving obj. from its regular state
7
Q
On-Die Termination (2)
A
- o/p imp. of buffer to be constant over the op. range + close to Z0
- ideal soln has no extra components but hard to achieve as o/p imp. difficult to control
8
Q
Series Source Termination (3)
A
- add resistor w/ o/p buffer, ZS + RS = Z0
- works well if Rs >> o/p imp
- uncertainty if Rs is small
- resistors add cost + take up space
9
Q
Parallel Load Termination (2)
A
- add a resistor in parallel w/ o/p buffer to remove reflection
- extra power dissipation in the extra resistor as well as cost + space
