Protection circuit for radio frequency power amplifier
Embodiments of circuits, apparatuses, and systems for a protection circuit to protect against overdrive or overvoltage conditions. Other embodiments may be described and claimed.
1. A circuit comprising:
a transmission line configured to transmit a radio frequency (RF) signal;
a primary power transistor having a base coupled with the transmission line, wherein the primary power transistor is configured to amplify the RF signal; and
a protection circuit coupled with the transmission line and configured to detect an overdrive or overvoltage condition and to reduce a current or voltage at the power amplifier based on a detection of the overdrive or overvoltage condition,
wherein the protection circuit includes:
a compensator configured to compensate for an amplitude or phase of the RF signal; and
two transistors coupled with the transmission line via the compensator and a shunt line.
2. The circuit of claim 1 , wherein the two transistors are arranged in a Darlington configuration.
3. The circuit of claim 1 , wherein the compensator is configured to compensate for the phase of the RF signal to increase linearity of a response profile of the primary power transistor.
4. The circuit of claim 1 , wherein the protection circuit further comprises:
a detector configured to track a trigger voltage and to provide a biasing voltage to the two transistors that is proportional to the trigger voltage.
5. The circuit of claim 4 , wherein the detector comprises a voltage divider coupled with an emitter of a first transistor of the two transistors and further coupled with a base of a second transistor of the two transistors.
6. The circuit of claim 5 , wherein the detector further comprises:
a capacitor coupled with the emitter of the first transistor.
7. The circuit of claim 4 , wherein the detector is coupled with a bias voltage node that is configured to provide a bias voltage, through an input bias network, to the base of the primary power transistor.
8. The circuit of claim 4 , wherein the detector is coupled with a control voltage node that is configured to provide a bias voltage, through an output bias network, to a collector of the primary power transistor.
9. A circuit comprising:
a transmission line configured to transmit a radio frequency (RF) signal;
a primary power transistor having a base coupled with the transmission line, wherein the primary power transistor is configured to amplify the RF signal; and
a protection circuit coupled with the transmission line and configured to detect an overdrive or overvoltage condition and to reduce a current or voltage at the power amplifier based on a detection of the overdrive or overvoltage condition,
wherein the protection circuit is coupled with the transmission line via an emitter follower;
wherein the protection circuit further comprises an operational amplifier;
wherein the sensing resistor is coupled with a voltage control node of the operational amplifier and is coupled with the transmission line via a collector of the emitter follower; and
wherein an output of the operational amplifier is coupled with a base of the emitter follower.
10. A system comprising:
a transceiver configured to provide a radio frequency (RF) signal;
amplification circuitry coupled with the transceiver, the amplification circuitry including a primary power transistor configured to receive and amplify the RF signal;
a transmission line configured to transmit the RF signal from the transceiver to a base of the primary power transistor; and
a protection circuit coupled with the transmission line and configured to detect an overdrive or overvoltage condition and to reduce a current or voltage at the primary power transistor based on a detection of the overdrive or overvoltage condition,
wherein the protection circuit includes:
a compensator configured to compensate for an amplitude or phase of the RF signal; and
two transistors coupled with the transmission line via the compensator and a shunt line.
11. The system of claim 10 , wherein the protection circuit further comprises:
a detector configured to track a trigger voltage and to provide a biasing voltage to the two transistors that is proportional to the trigger voltage.
12. The system of claim 11 , wherein the detector comprises a voltage divider coupled with an emitter of a first transistor of the two transistors and further coupled with a base of a second transistor of the two transistors.
13. The system of claim 12 , wherein the detector further comprises:
a capacitor coupled with the emitter of the first transistor.
14. The system of claim 11 , wherein the detector is coupled with a voltage node that is configured to provide a bias voltage through an input bias network to the base of the primary power transistor or through an output bias network to a collector of the primary power transistor.
15. A method comprising:
generating, by a transceiver, a radio frequency (RF) signal;
transmitting, by the transceiver, the RF signal along a transmission line to a primary power transistor;
detecting, by a protection circuit coupled with the transmission line, an overdrive condition or an overvoltage condition, wherein said detecting includes:
tracking, with a detector of the protection circuit, a trigger voltage; and
providing a biasing voltage to two transistors of the protection circuit that is proportional to the trigger voltage; and
reducing, by the protection circuit, a current or voltage at the primary power transistor based on said detecting.
16. The method of claim 15 , wherein said reducing comprises shunting at least a portion of the RF signal via the protection circuit.
17. The method of claim 15 , further comprising:
compensating, with the protection circuit, for a phase of the RF signal to increase linearity of a response profile of the primary power transistor.
18. A system comprising:
a transceiver to:
generate a radio frequency (RF) signal;
transmit the RF signal along a transmission line to a primary power transistor;
a protection circuit coupled with the transmission line to detect an overdrive condition or an overvoltage condition, wherein the protection circuit includes:
two transistors; and
a detector to track a trigger voltage and to provide a biasing voltage to the two transistors of the protection circuit that is proportional to the trigger voltage,
wherein the protection is further to reduce a current or voltage at the primary power transistor based on said detecting.
19. The system of claim 18 , wherein the protection circuit is to reduce the current or voltage by shunting, through the two transistors at least a portion of the RF signal.
20. The system of claim 18 , wherein the protection circuit further comprises:
a compensator to compensate for a phase of the RF signal to increase linearity of the primary power transistor.