Radar transceiver

1. A radar transceiver, comprising:

a chirp generator for generating a chirp having an initial frequency and a final frequency;

a controllable variable gain amplifier having an input connected to an output of the chirp generator; and

a control unit connected to a control input on the chirp generator and to a control input on the controllable variable gain amplifier, wherein the control unit is adapted to:

output a first control signal to the chirp generator such that the chirp generator starts generating the chirp;

output a second control signal to the controllable variable gain amplifier such that the controllable variable gain amplifier starts increasing an amplification in the controllable variable gain amplifier from a first amplification level, along a slope, to a second amplification level; and

output the first control signal and the second control signal such that a start of generating the chirp coincides with a start of the increase in amplification.

2. The radar transceiver according to claim 1 , wherein the chirp generator comprises a digitally controlled oscillator.

3. The radar transceiver according to claim 1 , wherein the controllable variable gain amplifier comprises a digitally controlled amplifier.

4. The radar transceiver according to claim 1 ,

wherein the chirp ends after a chirp duration, and

wherein the control unit is further adapted to output the second control signal to the controllable variable gain amplifier such that the controllable variable gain amplifier starts decreasing the amplification in the controllable variable gain amplifier from the second amplification level, along a slope, to a third amplification level such that an end of the chirp duration coincides with a time at which the amplification in the controllable variable gain amplifier reaches the third amplification level.

5. The radar transceiver according to claim 4 , wherein the control unit is further adapted to output the first control signal such that a time duration between a start of at least two consecutive chirps is greater than the chirp duration.

6. The radar transceiver according to claim 5 ,

wherein the controllable variable gain amplifier has a first operating mode and a second operating mode,

wherein a power consumption in the controllable variable gain amplifier is higher in the first operating mode than in the second operating mode, and

wherein the control unit is further adapted to set the controllable variable gain amplifier in the first operating mode before a start of the chirp duration and set the controllable variable gain amplifier in the second operating mode after an end of the chirp duration.

7. The radar transceiver according to claim 6 , wherein the slope is linear.

8. The radar transceiver according to claim 7 , wherein a time duration during which the amplification in the controllable variable gain amplifier increases from the first amplification level to the second amplification level is between 0% and 10% of the chirp duration.

9. The radar transceiver according to claim 8 , wherein a time duration during which the amplification in the controllable variable gain amplifier decreases from the second amplification level to the third amplification level is between 0% and 10% of the chirp duration.

10. The radar transceiver according to claim 9 ,

wherein the radar transceiver comprises receiver circuitry adapted to operate in a first operating mode and a second operating mode,

wherein a power consumption in the receiver circuitry is higher in the first operating mode than in the second operating mode, and

wherein the control unit is further adapted to set the receiver circuitry in the second operating mode after an end of the chirp duration.

11. The radar transceiver according to claim 10 , wherein the control unit is further adapted to:

receive an input signal representative of a presence or a velocity of an object within a detection range of the radar transceiver; and

adjust a time duration between a start of at least two consecutive chirps based on the received input signal.

12. A method implemented in a radar transceiver, comprising:

generating a chirp using a chirp generator;

simultaneously amplifying, using a controllable variable gain amplifier, the chirp at a first amplification level; and

increasing the amplification of the chirp from the first amplification level along a slope to a second amplification level during at least a portion of a time interval during which the chirp is generated.

13. The method according to claim 12 ,

wherein the chirp ends after a chirp duration, and

wherein the method further comprises decreasing, subsequent to reaching the second amplification level, the amplification along a slope to a third amplification level such that an end of the chirp duration coincides with a time instant at which the amplification reaches the third amplification level.

14. The method according to claim 13 , further comprising generating consecutive chirps such that a time duration between a start of at least two consecutive chirps is greater than the chirp duration.

15. The method according to claim 14 ,

wherein the controllable variable gain amplifier has a first operating mode and a second operating mode,

wherein a power consumption in the controllable variable gain amplifier is higher in the first operating mode than in the second operating mode, and

wherein the method further comprises:

setting the controllable variable gain amplifier in the first operating mode before a start of the chirp duration; and

setting the controllable variable gain amplifier in the second operating mode after an end of the chirp duration.

16. The method according to claim 15 , wherein the slope is linear.

17. The method according to claim 16 , wherein a time duration during which the amplification in the controllable variable gain amplifier increases from the first amplification level to the second amplification level is between 0% and 10% of the chirp duration.