Drift compensation
The present disclosure relates to a method for controlling a device comprising an oscillation circuit, configured to provide a clock signal to a radio frequency circuit, and an antenna, in which the enabling of the passage of the signal from the circuit to the antenna is delayed with respect to an instant from which a power amplifier of the circuit is enabled.
1. A method for controlling a device, the method comprising:
providing, by an oscillation circuit, a clock signal to a radio frequency (RF) circuit;
enabling a power amplifier of the RF circuit to generate an RF signal;
after the enabling the power amplifier, delaying enablement of a passage of the RF signal from the RF circuit to an antenna by a delay; and
after the delay, enabling the passage of the RF signal from the RF circuit to the antenna.
2. The method of claim 1 , wherein the enabling of the passage of the RF signal from the RF circuit to the antenna corresponds to a shift of a switch from a first position to a second position, the first position being configured so that no emission can be transmitted via the antenna, and the second position being configured so that emissions can be transmitted via the antenna.
3. The method of claim 1 , further comprising:
generating a single control signal to enable the power amplifier and the passage of the RF signal from the RF circuit to the antenna; and
adding the delay to the single control signal before the single control signal reaches a switch coupled between the RF circuit and the antenna, the delay being with respect to the single control signal reaching the power amplifier.
4. The method of claim 1 , wherein a duration of the delay is less than one second.
5. The method of claim 1 , wherein a duration of the delay is greater than 5 ms.
6. The method of claim 1 , wherein a duration of the delay depends on a temperature measured by a temperature sensor of the device.
7. The method of claim 6 , wherein the or each temperature measured by the temperature sensor is indicative of an ambient temperature.
8. The method of claim 6 , wherein the device comprises a plurality of duration values of the delay stored in a memory, each duration value corresponding to a range of temperatures.
9. The method of claim 8 , wherein the duration values associated with some of the temperatures are zero.
10. The method of claim 8 , wherein at least one duration value associated with at least one temperature is nonzero.
11. The method of claim 1 , wherein the RF circuit is an RF transmitter.
12. The method of claim 1 , wherein the device comprises, coupled in series, a first variable capacitor, a first capacitor, a quartz crystal and a second variable capacitor, and the method further comprises controlling capacitances of the first and second variable capacitors to be above 50% of maximum capacitances of the first and second variable capacitors, respectively.
13. The method of claim 12 , further comprising:
preheating the quartz crystal; and
enabling emission of transmitted signals as a temperature of the quartz crystal decreases.
14. A device comprising:
a radio frequency (RF) circuit;
an antenna coupled to the RF circuit;
an oscillation circuit configured to provide a clock signal to the RF circuit; and
a control circuit configured to:
enable a power amplifier of the RF circuit; and
enable a passage of an RF signal from the RF circuit to the antenna, wherein the passage of the RF signal from the circuit to the antenna is delayed with respect to an instant from which the power amplifier is enabled.
15. The device of claim 14 , further comprising a sensor configured to measure a temperature or a value representative of the temperature.
16. The device of claim 14 , further comprising a memory configured to store duration values of delays corresponding to ranges of temperature.
17. The device of claim 14 , wherein the oscillation circuit comprises, coupled in series, a first variable capacitor, a first capacitor, a quartz crystal and a second variable capacitor.
18. The device of claim 17 , further comprising a heater configured to increase a temperature of the quartz crystal.
19. The device of claim 14 , further comprising a switch coupled between the RF circuit and the antenna, and controlled by the control circuit, wherein the switch has a first position configured so that no emission can be transmitted via the antenna, and a second position configured so that emissions can be transmitted via the antenna.
20. The device of claim 19 , wherein the control circuit is configured to
generate a single control signal to enable the power amplifier and the passage of the RF signal from the RF circuit to the antenna; and
wherein the device further comprises a delay circuit configured to add the delay to the single control signal before the single control signal reaches the switch coupled between the RF circuit and the antenna, the delay being with respect to the single control signal reaching the power amplifier.