Method for controlling the operating point of a transistor of a power amplifyer
AssigneeEvolium S.A.S.
InventorRolf Nuchter
Life of this patent
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Abstract
The invention relates to a method for controlling the operating point of a transistor of a power amplifier for amplifying time division multiplex (access) TDM(A)-signals. Methods to compensate drifts of the operating point caused by temperature variations are in principle known in the art. However, the methods known in the art have the disadvantage that they are not precise enough during the operation of such power amplifiers, in particular when amplifying high-frequency TDM(A)-signals. In order to overcome said problem the invention proposes to carry out the controlling of the operating point during null power time slots of said TDM-signal.
Claims15
Method for controlling the operating point of a transistor of a power amplifier for amplifying time division multiplex (access) TDM(A)-signals, comprising the steps of:
- detecting a deviation between a set operating point and an actual operating point of said transistor;
- detecting the occurrence of said null power time slots or using the knowledge when they occur;
- and
- adjusting the bias of the gate/base of said transistor according to said deviation in order to re-establish said set operating point;
- wherein
- these steps are carried out during separate null power time slot of said TDM(A)-signals.
Method according to one of the preceding claims, wherein the null power time slots to be used arise consecutively or not within said TDM(A)-signal.
Method according to one of the preceding claims, wherein the adjustment of the bias is carried out iteratively during several control loops.
Method according to one of the preceding claims, wherein the set operating point is adapted in response to the temperature in the surrounding of the transistor.
Method according to one of the preceding claims, wherein bias means the gate/base voltage for driving the gate/base of the transistor.
Method according to one of the preceding claims, wherein the controlling of the operating point of the transistor is done only after the transistor has reached a steady state with respect to its temperature after a switch-on of the power amplifier.
Power amplifier for amplifying time division multiplex (access) TDM(A)-signals in a TDM(A) system, in particular in a Global System for Mobile Communications GSM, comprising
- a transistor for amplifying said TDM(A)-signals;
- a shunt being connected in series to the drain-source path or collector-emitter path of said transistor for providing a measurement voltage, the constant component of which representing the actual operating point of said transistor;
- and
- a controlling unit for detecting a deviation between a set operating point and said actual operating point, for detecting the occurrence of null power time slots within said TDM(A)-signals and for adjusting the bias of the gate/base of said transistor according to said deviation in order to re-establish said set operating point;
- wherein
- the controlling unit is embodied to carry out the detecting and adjusting steps during separate ones of said detected null power time slots.
Dependencies are inferred from the claim text.