19-02-2018, 10:30 AM
Temperature compensation can be critical in some situations.
For example, when the BB105 varicap diode was introduced for use in Varicap TV Tuners, it was important to ensure that the supply voltage was compensated to track the temperature coefficient of the diodes, otherwise tuning drift would be experienced until the temperature stabilised - particularly important in the valve sets of the time, of course. Eventually, Mullard introduced the TAA550 stabiliser which had the inverse temperature coefficient to that of the diodes but that didn't exist when we first started using them.
The solution was a string of five zener diodes - 3 x 6.8V and 2 x 3.3V - which had with the correct temperature coefficient and produced a supply of 27V (the maximum reverse voltage of a BB105 was 28V).
For example, when the BB105 varicap diode was introduced for use in Varicap TV Tuners, it was important to ensure that the supply voltage was compensated to track the temperature coefficient of the diodes, otherwise tuning drift would be experienced until the temperature stabilised - particularly important in the valve sets of the time, of course. Eventually, Mullard introduced the TAA550 stabiliser which had the inverse temperature coefficient to that of the diodes but that didn't exist when we first started using them.
The solution was a string of five zener diodes - 3 x 6.8V and 2 x 3.3V - which had with the correct temperature coefficient and produced a supply of 27V (the maximum reverse voltage of a BB105 was 28V).
