W
Warren
- Jan 1, 1970
- 0
I am curious about common base configuration biasing. When
using a _split_ supply, how are the emitter and collector
resistors chosen?
VCC
+
|
.-.
| |
| | RC
'-'
|| | ||
-----||-------|----- --------------||-----
|| | ^ / ||
| ---
.-. |
RE | | |
| | ===
'-' GND
|
-
VEE
1) I assume that you start with a desired Ic current.
2) Given that the base is DC grounded (in this example at
least), then it follows that the top of RE is -0.6V.
3) So I assume that you compute RE = (VEE-0.6) / Ic.
It appears that the collector can only swing between near
ground and +VCC, so I would assume you target VC at VCC / 2.
4) Hence Rc = (VCC / 2) / Ic.
Is that the overall procedure?
I know you can also arrange it so the base is only AC
grounded, which then allows greater flexibility for choosing
input/output impedances, not to mention output swing. But you
often see this configuration listed as an example.
using a _split_ supply, how are the emitter and collector
resistors chosen?
VCC
+
|
.-.
| |
| | RC
'-'
|| | ||
-----||-------|----- --------------||-----
|| | ^ / ||
| ---
.-. |
RE | | |
| | ===
'-' GND
|
-
VEE
1) I assume that you start with a desired Ic current.
2) Given that the base is DC grounded (in this example at
least), then it follows that the top of RE is -0.6V.
3) So I assume that you compute RE = (VEE-0.6) / Ic.
It appears that the collector can only swing between near
ground and +VCC, so I would assume you target VC at VCC / 2.
4) Hence Rc = (VCC / 2) / Ic.
Is that the overall procedure?
I know you can also arrange it so the base is only AC
grounded, which then allows greater flexibility for choosing
input/output impedances, not to mention output swing. But you
often see this configuration listed as an example.