Hi, I have a simple question.
For buffer/preamp design (e.g. Diamond), use output transistor like BC547 or BD139.
What is the value of Iq that the buffer/preamp work in class A?
and when in class AB?
Use BC547 (supply +/-8V), Iq = 0.5mA is class AB and Iq = 10mA is class A?
Zout will vary with different Iq levels?
For buffer/preamp design (e.g. Diamond), use output transistor like BC547 or BD139.
What is the value of Iq that the buffer/preamp work in class A?
and when in class AB?
Use BC547 (supply +/-8V), Iq = 0.5mA is class AB and Iq = 10mA is class A?
Zout will vary with different Iq levels?
Hi Haven,
what is your load on the buffer/pre-amp?
How much capacitance is in that load.
How much current does the load//capacitance take at maximum slew rate?
From that answer you can decide whether ClassA is feasible and if it is, determine the output bias current and the quiescent current to meet that worst case demand.
If you think that worst case current cannot be met using ClassA, then push/pull ClassAB can be used to satisfy the worst case demand and you adopt a lesser ClassA capability for your source.
A single ended ClassA stage can never exceed it's output bias current.
what is your load on the buffer/pre-amp?
How much capacitance is in that load.
How much current does the load//capacitance take at maximum slew rate?
From that answer you can decide whether ClassA is feasible and if it is, determine the output bias current and the quiescent current to meet that worst case demand.
If you think that worst case current cannot be met using ClassA, then push/pull ClassAB can be used to satisfy the worst case demand and you adopt a lesser ClassA capability for your source.
A single ended ClassA stage can never exceed it's output bias current.
Hi Haven,
what is your load on the buffer/pre-amp?
How much capacitance is in that load.
How much current does the load//capacitance take at maximum slew rate?
From that answer you can decide whether ClassA is feasible and if it is, determine the output bias current and the quiescent current to meet that worst case demand.
If you think that worst case current cannot be met using ClassA, then push/pull ClassAB can be used to satisfy the worst case demand and you adopt a lesser ClassA capability for your source.
A single ended ClassA stage can never exceed it's output bias current.
Hi and thanks, clear answers.
The load on buffer/preamp is an differencial input of a power amplifier, not low load.
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