Abstract: A detection circuit for detecting the output power of a power amplifier comprises a first current minor transistor (Ti 1) having a base, which is connectable to a power transistor (T10), and a collector, a RF detection means (RF-det) for detecting the RF current flowing through the current mirror transistor (T11). Said RF detection means (RFdet) is connected to the collector of said first current mirror transistor (T11). Said detection circuit further comprises a biasing means (bias-RF-det) for biasing said RF detection means (RF-det), wherein said biasing means is connected to said collector of said first current mirror (T11) and said RF detection means (RF-det).

Abstract: An RF power amplifier according to the invention comprises a plurality of parallel output transistors (HBT,1,1 to HBT,1,N) connected to a power supply. A plurality of base resistors (Rb,1,1 to Rb,1,N) for the output transistors (HBT,1,1 to HBT,1,N) and a plurality of input capacitors (Cb,1 to Cb,N), each coupled in parallel to receive an RF signal input and connected via at least one additional passive component to the inputs of each corresponding output transistor (HBT,1,1 to HBT,1,N), are provided An output for an RF output signal is obtained from the parallel connection of the output transistors (HBT,1,1 to HBT,1,N). The transistors (HBT,1,1 to HBT,1,N) are heterojunction bipolar transistors.

Abstract: A bias circuit for a radio frequency linear power amplifier having an input for selecting one of a plurality of operating modes varying in quiescent current of an bipolar transistor, a thermally responsive element for sensing a temperature, a circuit for biasing the output bipolar transistor, receiving said selecting input and incorporating said thermally responsive element, for maintaining linear performance in each of said modes over a range of temperatures, and a filter 6, 41, 42, 43 for attenuating noise generated within the linear power amplifier. The use of a tank circuit at the collector of a power radio frequency transistor, having an inductor capable of handling the collector current, resonating with a capacitor at the design frequency, permits a reduction in the required inductance and therefore higher levels of integration.

Abstract: A bias circuit for a radio frequency linear power amplifier having an input for selecting one of a plurality of operating modes varying in quiescent current of an bipolar transistor, a thermally responsive element for sensing a temperature, a circuit for biasing the output bipolar transistor, receiving said selecting input and incorporating said thermally responsive element, for maintaining linear performance in each of said modes over a range of temperatures, and a filter 6, 41, 42, 43 for attenuating noise generated within the linear power amplifier. The use of a tank circuit at the collector of a power radio frequency transistor, having an inductor capable of handling the collector current, resonating with a capacitor at the design frequency, permits a reduction in the required inductance and therefore higher levels of integration.