Bias thermal
stabilization
Bias
thermal stabilization is a variable voltage source that
adjusts according to temperature fluctuations, and is used to
compensate bias in an output power amplifier stage.
Primarily
used for biasing outputs Class A/B amplifiers.
The
cheapest bias method consists of three diodes in series (for
Darlington powered outputs).
At
lower temperatures, diode’s Vf (forward bias voltage)
increases, but
decreases at high temperatures. In this way compensates
junction Vbe of the output stage is tracked by the Vbe
temperature variations, maintaining the same current over the
full temperature range of the amplifier
Bipolar
transistors offer much better temperature compensation vs.
diodes.
