Earth referenced bias into floating circuit?

Click For Summary
SUMMARY

Connecting an Earth referenced bias voltage to the gate of a MOSFET or op-amp powered by a floating power supply leads to ineffective biasing and potential circuit instability. The introduction of an Earth reference can create unintended current paths, resulting in excessive hum and unpredictable behavior. Specifically, in FET circuits, incorrect voltage levels can prevent proper charging and discharging of gate capacitance, causing erratic performance. Therefore, maintaining a consistent reference point is crucial for reliable circuit operation.

PREREQUISITES
  • Understanding of MOSFET and op-amp operation
  • Knowledge of floating power supply concepts
  • Familiarity with biasing techniques in electronic circuits
  • Basic principles of circuit grounding and reference voltages
NEXT STEPS
  • Research proper biasing methods for MOSFETs and op-amps
  • Learn about floating power supply design and implications
  • Explore techniques to minimize hum in electronic circuits
  • Study the effects of gate capacitance in FET circuits
USEFUL FOR

Electronics engineers, hobbyists designing analog circuits, and anyone troubleshooting biasing issues in MOSFET or op-amp applications.

coinmaster
Messages
41
Reaction score
0
What happens if I for example, connect an Earth referenced bias voltage to the gate/grid/input of a mosfet/tube/opamp that uses a floating power supply?
Does the bias simply not work or does the circuit somehow become Earth referenced?
 
Engineering news on Phys.org
I suspect you know the answer to this. There always has to be a return of some kind. It is likely you would introduce a lot of hum. It would not bias in a useable or constructive way.
 
In the case of FETs you will get some really confusing results. If you happen to luck out and get all of the voltages correct you will not have current paths to charge and discharge the gate capacitance properly. Shenanigans will ensue.

BoB
 

Similar threads

Replies
3
Views
2K
Replies
18
Views
6K
Replies
4
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
39
Views
6K
  • · Replies 15 ·
Replies
15
Views
7K
  • · Replies 12 ·
Replies
12
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
55
Views
8K
  • · Replies 13 ·
Replies
13
Views
7K