Nxp B.v.

Koninklijke Philips Corporation N.V.

John Joseph Hug

Adrianus Van Bezooijen

Richard Keenan

Christophe Joly

Ronald Koster

Rob Mathijs Heeres

Christophe Chanlo

Dmitry Pavlovich Prikhodko

Dmitri Pavlovitch Prikhodko

Niels Kramer

Dmitri P Prikhodko

A current limiting circuit, especially for an RF power amplifier (PA) having a power control loop. The circuit is adapted to sense a representation of a bias current fed to a final stage of the PA. The sensed representation of the bias current is compared to a predetermined reference current and a signal is fed back to the power control loop upon the sensed representation of the bias current exceeding the reference current so as to limit output current of the PA. This provides a limitation of a current drawn by the PA which is generally insensitive to supply voltage and temperature variations. Optionally, a second circuit may be added to limit current drawn by the PA. The second circuit comprising a high accuracy VI converter that is adapted to compare a voltage VLIM representing a feed-back voltage of the power control loop and a predetermined reference voltage VBGAP. The circuit is operatively connected to the VI converter so as to reduce the output current lout upon the voltage VLIM representing the feed-back voltage exceeding the predetermined reference voltage VBGAP. Under antenna mismatch conditions both circuits help to limit a supply current drawn by the PA compared to prior art power control loops that are unable to detect and limit a high current draw under mismatch conditions.

Current limiting circuit for RF power amplifier

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

Output power detection circuit

An RF power amplifier according to the invention comprises a plurality of parallel output transistors (HBT,to HBT,,N) connected to a power supply. A plurality of base resistors (Rb,to Rb,,N) for the output transistors (HBT,to HBT,,N) and a plurality of input capacitors (Cb,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,to HBT,,N), are provided An output for an RF output signal is obtained from the parallel connection of the output transistors (HBT,to HBT,,N). The transistors (HBT,to HBT,,N) are heterojunction bipolar transistors.

RF power amplifier

A bias circuit for a radio frequency linear power amplifier includes an input for selecting an operating mode varying in quiescent current of an output transistor. A sensor senses a current through the output transistor and a circuit biases the output transistor for maintaining linear performance in each of mode over a range of temperatures. A filter attenuates noise generated within the linear power amplifier. 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.

Linear power amplifier

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Nijmegen, Netherlands

John Joseph Hug