Current surge protection circuits for base station antennas having remote electronic tilt capability and related methods
A system includes a remote electronic tilt phase shifter module, a motor, a mechanical linkage that connects the motor to the remote electronic tilt phase shifter module, a current management circuit that generates a motor control signal responsive to a current control signal, and a driver circuit that is configured to selectively connect the motor to a power supply in response to the motor control signal.
1. A system, comprising:
a remote electronic tilt phase shifter module;
a motor;
a mechanical linkage that connects the motor to the remote electronic tilt phase shifter module;
a current management circuit that generates a motor control signal responsive to a current control signal; and
a driver circuit that is configured to selectively connect the motor to a power supply in response to the motor control signal.
2. The system of claim 1 , wherein the current control signal is a pulse width modulated signal.
3. The system of claim 2 , wherein the motor is a direct current motor; and
wherein a duty cycle of the pulse width modulated signal is based on a magnitude of current drawn by the direct current motor.
4. The system of claim 3 , wherein the duty cycle of the pulse width modulated signal is based on a defined electromagnetic interference (EMI) standard.
5. The system of claim 4 , wherein the EMI standard comprises at least one of EN55022, CFR 47 Part 15, CISPR 22, and ICES-003.
6. The system of claim 3 , wherein the duty cycle of the pulse width modulated signal monotonically increases until reaching a maximum value.
7. The system of claim 1 , wherein the system further comprises:
an antenna coupled to the remote electronic tilt phase shifter module;
wherein the remote electronic tilt phase shifter module is configured to adjust at least one of an elevation angle of the antenna and an azimuth angle of the antenna responsive to movement of the mechanical linkage by the motor.
8. The system of claim 1 , wherein the driver circuit is further configured to connect the motor to the power supply when the motor control signal is in a first logic state and to disconnect the direct current motor from the power supply when the motor control signal is in a second logic state.
9. The system of claim 1 , wherein the driver circuit comprises an H-bridge circuit comprising a first pair of switches and a second pair of switches;
wherein one of the first pair of switches is responsive to the motor control signal when the motor is configured to turn in a first direction and one of the second pair of switches is responsive to the motor control signal when the motor is configured to turn in a second direction.
10. The system of claim 1 , wherein the driver circuit comprises an H-bridge circuit comprising a first pair of switches and a second pair of switches;
wherein one of the first pair of switches is responsive to the motor control signal when the motor is configured to turn in a first direction and one of the second pair of switches is responsive to the motor control signal when the motor is configured to turn in a second direction.
11. A system, comprising:
a remote electronic tilt phase shifter module;
a motor;
a mechanical linkage that connects the motor to the remote electronic tilt phase shifter module;
a current management circuit that generates a motor control signal responsive to a comparison between a current drawn by the motor and a defined current threshold; and
a driver circuit that is configured to selectively connect the motor to a power supply in response to the motor control signal.
12. The system of claim 11 , wherein the defined current threshold is based on an environmental temperature.
13. The system of claim 11 , wherein the defined current threshold is based on a defined electromagnetic interference (EMI) standard.
14. The system of claim 13 , wherein the EMI standard comprises at least one of EN55022, CFR 47 Part 15, CISPR 22, and ICES-003.
15. The system of claim 11 , wherein the current management circuit comprises a comparator circuit that is configured to generate a comparison signal at an output thereof responsive to the current drawn by the motor and the defined current threshold.
16. The system of claim 15 , wherein the comparator circuit comprises an output circuit that is configured to generate the comparison signal at the output of the comparator circuit, the output circuit comprising an open collector or open drain circuit.
17. The system of claim 15 , wherein the current management circuit further comprises a resistor-capacitor network coupled to the output of the comparator circuit.
18. The system of claim 17 , wherein the resistor-capacitor network has a first time constant when the comparison signal is in a first logic state and a second time constant when the comparison signal is in a second logic state, the second time constant being different than the first time constant.
19. The system of claim 11 , wherein the system further comprises:
an antenna coupled to the remote electronic tilt phase shifter module;
wherein the remote electronic tilt phase shifter module is configured to adjust at least one of an elevation angle of the antenna and an azimuth angle of the antenna responsive to movement of the mechanical linkage by the motor.
20. The system of claim 11 , wherein the driver circuit is further configured to connect the motor to the power supply when the motor control signal is in a first logic state and to disconnect the direct current motor from the power supply when the motor control signal is in a second logic state.