BJT differential pair
Large-signal tanh transfer and differential transconductance with a fixed tail current.
Development preview. Check the assumptions below before relying on a result. Calculations run in your browser.
How it calculates
Assumptions
- Ideal fixed tail current, matched BJTs, infinite beta and Early voltage; collector saturation and common-mode limits must be checked separately.
- Gain limit is local transconductance reduction, not total harmonic distortion. Differential load is connected between collectors.
Worked example
These are the calculator's default inputs. Change any input above to recalculate.
Inputs
- Tail current
- 0.002 A
- Each collector resistor
- 4700 Ω
- Differential load resistance
- 100000 Ω
- Differential input voltage
- 0.01 V
- Allowed transconductance reduction
- 1 %
- Device temperature
- 25 °C
Results
- Differential output
- -1.65135 V
- Differential output gain
- -167.214
- Collector current 1
- 0.00119219 A
- Collector current 2
- 0.000807811 A
- Zero-input differential transconductance
- 0.0389217 S
- Single-ended output gain
- -83.607
- Differential input magnitude at gain limit
- 0.00515575 V