Spurious emissions detection and calibration using envelope detector
Methods and systems for operating a transceiver are described. A transceiver can include an upconverting mixer, a downconverting mixer, a controller, and an envelope detector. The upconverting mixer can mix an input signal with a local oscillator (LO) signal to generate a transmitter signal. The envelope detector can receive the transmitter signal outputted from the upconverting mixer and output an envelope of the transmitter signal to an output line of the downconverting mixer. The envelope can indicate at least one of a leaked LO signal and an image signal. The controller can receive a calibration parameter that is based on at least one of the leaked LO signal and image signal and calibrate the upconverting mixer based on the calibration parameter.
1. A semiconductor device comprising:
an upconverting mixer configured to mix an input signal with a local oscillator (LO) signal to generate a transmitter signal;
a downconverting mixer;
an envelope detector configured to:
receive the transmitter signal outputted from the upconverting mixer; and
output an envelope of the transmitter signal to an output line of the downconverting mixer, wherein the envelope indicates at least one of a leaked LO signal and an image signal; and
a controller configured to:
disable a power amplifier connected to an output terminal of the upconverting mixer;
disable a low noise amplifier connected to an input terminal of the downconverting mixer; and
in response to disabling the power amplifier and the low noise amplifier, enable the envelope detector.
2. The semiconductor device of claim 1 , wherein an input terminal of the envelope detector is connected to the output terminal of the upconverting mixer and an input of the power amplifier.
3. The semiconductor device of claim 1 , wherein the envelope detector outputs the envelope of the transmitter signal to a variable gain amplifier.
4. The semiconductor device of claim 1 , wherein:
the leaked LO signal is at a first frequency in the envelope, wherein the first frequency is an intermediate frequency; and
the image signal is at a second frequency in the envelope, wherein the second frequency doubles the intermediate frequency.
5. The semiconductor device of claim 1 , wherein the envelope further indicates at least one harmonic of the LO signal.
6. A semiconductor device comprising:
an upconverting mixer configured to mix an input signal with a local oscillator (LO) signal to generate a transmitter signal;
a downconverting mixer;
a controller; and
an envelope detector configured to:
receive the transmitter signal outputted from the upconverting mixer; and
output an envelope of the transmitter signal to an output line of the downconverting mixer, wherein the envelope indicates at least one of a leaked LO signal and an image signal,
wherein the controller is configured to:
disable a power amplifier connected to an output terminal of the upconverting mixer;
disable a low noise amplifier connected to an input terminal of the downconverting mixer;
in response to disabling the power amplifier and the low noise amplifier, enable the envelope detector;
receive a calibration parameter that is based on at least one of the leaked LO signal and image signal; and
calibrate the upconverting mixer based on the calibration parameter.
7. The semiconductor device of claim 6 , wherein an input terminal of the envelope detector is connected between the output terminal of the upconverting mixer and an input of the power amplifier.
8. The semiconductor device of claim 6 , wherein the envelope detector outputs the envelope of the transmitter signal to a variable gain amplifier.
9. The semiconductor device of claim 6 , wherein:
the leaked LO signal is at a first frequency in the envelope, wherein the first frequency is an intermediate frequency; and
the image signal is at a second frequency in the envelope, wherein the second frequency doubles the intermediate frequency.
10. The semiconductor device of claim 6 , wherein the envelope further indicates at least one harmonic of the LO signal.
11. The semiconductor device of claim 6 , wherein the envelope is outputted to a baseband processor, and the controller is configured to receive the calibration parameter from the baseband processor.
12. A method for operating a transceiver, the method comprising:
mixing an input signal with a local oscillator (LO) signal to generate a transmitter signal;
disabling a power amplifier connected to an output terminal of an upconverting mixer;
disabling a low noise amplifier connected to an input terminal of an downconverting mixer;
in response to disabling the power amplifier and the low noise amplifier, enabling an envelope detector to output an envelope;
tapping the transmitter signal at an output terminal of the upconverting mixer in the transceiver;
outputting the envelope of the transmitter signal to an output line of the downconverting mixer in the transceiver, wherein the envelope indicates at least one of a leaked LO signal and an image signal; and
calibrating the upconverting mixer utilizing a calibration parameter that is based on the leaked LO signal and the image signal in the envelope.
13. The method of claim 12 , wherein outputting the envelope of the transmitter signal comprises operating the envelope detector to convert the transmitter signal into the envelope, and wherein the envelope detector is connected between the output terminal of the upconverting mixer and an input of the power amplifier.
14. The method of claim 12 , further comprising outputting the envelope to a variable gain amplifier.
15. The method of claim 12 , wherein:
the leaked LO signal is at a first frequency in the envelope, wherein the first frequency is an intermediate frequency; and
the image signal is at a second frequency in the envelope, wherein the second frequency doubles the intermediate frequency.
16. The method of claim 12 , wherein the envelope further indicates at least one harmonic of the LO signal.
17. The method of claim 12 , further comprising outputting the envelope to a baseband processor.
18. The method of claim 17 , wherein the calibration parameter is received at the transceiver from the baseband processor.