Circuit, system, and method for operating and calibrating a radio frequency transceiver

Patent metadata

Field	Value
Publication number	US-10158434-B2
Application number	US-201615333077-A
Country	US
Kind code	B2
Filing date	Oct 24, 2016
Priority date	Oct 24, 2016
Publication date	Dec 18, 2018
Grant date	Dec 18, 2018

Abstract

In accordance with an embodiment, a method for operating a radio frequency (RF) transceiver includes frequency-translating, using a local oscillator signal having a calibrated phase shift, a signal received at an antenna of an RF transceiver; filtering the frequency-translated signal using a programmable filter of the RF transceiver to produce a filtered frequency-translated signal; and changing a cutoff frequency of the programmable filter from a first cutoff frequency to a second cutoff frequency in response to the RF transceiver switching operation from a first mode to a second mode.

First claim

What is claimed is:

1. A method, comprising:
frequency-translating, using a local oscillator signal having a calibrated phase shift, a signal received at an antenna of a radio frequency (RF) transceiver;
filtering the frequency-translated signal using a programmable filter of the RF transceiver to produce a filtered frequency-translated signal;
changing a cutoff frequency of the programmable filter from a first cutoff frequency to a second cutoff frequency in response to the RF transceiver switching operation from a first mode to a second mode;
operating the RF transceiver in the second mode with the programmable filter having the second cutoff frequency for a first predetermined duration of time;
changing the cutoff frequency of the programmable filter from the second cutoff frequency to the first cutoff frequency while the RF transceiver is in the second mode and after the first predetermined duration of time has elapsed; and
operating the RF transceiver in the second mode with the programmable filter having the first cutoff frequency after changing the cutoff frequency of the programmable filter from the second cutoff frequency to the first cutoff frequency.

2. The method of claim 1 , wherein frequency-translating comprises downconverting.

3. The method of claim 1 , further comprising:
determining the calibrated phase shift based on a phase calibration that sets a direct current (DC) level of a frequency-translated signal; and
shifting a phase of the local oscillator signal by the calibrated phase shift.

4. The method of claim 3 , wherein determining the calibrated phase shift comprises:
shifting a phase of the local oscillator signal by a first phase shift;
transmitting, using the RF transceiver, a calibration signal;
frequency-translating, using the local oscillator signal having the first phase shift, a reflection of the calibration signal received at the antenna of the RF transceiver to produce a frequency-translated reflection of the calibration signal;
processing, using the RF transceiver, the frequency-translated reflection of the calibration signal to produce a first phase test signal; and
determining whether an amplitude of the first phase test signal is clipped.

5. The method of claim 4 , wherein the amplitude of the first phase test signal is clipped, and wherein the method further comprises:
shifting a phase of the local oscillator signal by a second phase shift different from the first phase shift;
transmitting, using the RF transceiver, the calibration signal;
frequency-translating, using the local oscillator signal having the second phase shift, the reflection of the calibration signal received at the antenna of the RF transceiver to produce a frequency-translated reflection of the calibration signal;
processing, using the RF transceiver, the frequency-translated reflection of the calibration signal to produce a second phase test signal; and
determining whether an amplitude of the second phase test signal is clipped.

6. The method of claim 4 , wherein the amplitude of the first phase test signal is not clipped, and wherein the method further comprises:
determining a DC level of the first phase test signal;
determining a difference between the DC level of the first phase test signal and a center of a dynamic range of an analog-to-digital convertor (ADC) of RF transceiver; and
determining whether a further difference has been determined, the further difference being a difference between a DC level of a third phase test signal and the center of the dynamic range of the ADC, the third phase test signal having an amplitude that is not clipped.

7. The method of claim 6 , wherein the further difference has been determined, and wherein the method further comprises:
selecting, as the calibrated phase shift, a phase shift corresponding to a smaller of the differences.

8. The method of claim 6 , wherein the further difference has not been determined, and wherein the method further comprises:
selecting the first phase shift as the calibrated phase shift.

9. The method of claim 1 , wherein the first predetermined duration of time is between about 1 nanosecond and about 50 nanoseconds.

10. The method of claim 1 , wherein the first mode is an inactive mode of the RF transceiver, and wherein the second mode is an active mode of the RF transceiver.

11. The method of claim 1 , wherein the first cutoff frequency is between about 20 kHz to about 50 kHz, and wherein the second cutoff frequency is greater than about 10 MHz.

12. The method of claim 1 , further comprising:
amplifying the filtered frequency-translated signal by a calibrated gain.

13. The method of claim 12 , further comprising:
determining the calibrated gain based on a gain calibration and a cutoff frequency calibration that reduces an amplitude clipping of a gain test signal.

14. The method of claim 13 , wherein determining the calibrated gain comprises:
increasing a gain of an amplifier of the RF transceiver from an initial gain setting to a first gain setting;
shifting a phase of the local oscillator signal by the calibrated phase shift;
transmitting, using the RF transceiver, a calibration signal;
frequency-translating, using the local oscillator signal having the calibrated phase shift, a reflection of the calibration signal to produce a frequency-translated reflection of the calibration signal;
filtering, using the programmable filter having the first cutoff frequency, the frequency-translated reflection of the calibration signal to produce a filtered frequency-translated reflection of the calibration signal;
amplifying, using the amplifier having the first gain setting, the filtered frequency-translated reflection of the calibration signal to produce a first gain test signal; and
determining whether an amplitude of the first gain test signal is clipped.

15. The method of claim 14 , wherein the amplitude of the first gain test signal is not clipped, and wherein the method further comprises selecting the first gain setting as the gain of the amplifier and the first cutoff frequency as a cutoff frequency of the programmable filter.

16. The method of claim 14 , wherein the amplitude of the first gain test signal is clipped and the first cutoff frequency is less than a maximum cutoff frequency of the programmable filter, and wherein the method further comprises:
increasing a cutoff frequency of the programmable filter from the first cutoff frequency to a third cutoff frequency;
transmitting, using the RF transceiver, the calibration signal;
frequency-translating, using the local oscillator signal having the calibrated phase shift, the reflection of the calibration signal to produce the frequency-translated reflection of the calibration signal;
filtering, using the programmable filter having the third cutoff frequency, the frequency-translated reflection of the calibration signal to produce a filtered frequency-translated reflection of the calibration signal;
amplifying, using the amplifier having the first gain setting, the filtered frequency-translated reflection of the calibration signal to produce a second gain test signal; and
determining whether an amplitude of the second gain test signal is clipped.

17. The method of claim 16 , wherein the amplitude of the second gain test signal is not clipped, and wherein the method further comprises selecting the first gain setting as the gain of the amplifier and the third cutoff frequency as the cutoff frequency of the programmable filter.

18. A circuit, comprising:
a mixer having an input po

Assignees

• Infineon Technologies Ag

Inventors

• Trotta Saverio
• Jungmaier Reinhard Wolfgang
• Noppeney Dennis
• Forstner Johann Peter
• Nasr Ismail
• Issakov Vadim
• Wickmann Andreas

Classifications

• H04B1/38

  Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving · CPC title

• H04B17/21

  for calibration; for correcting measurements · CPC title

• H04B17/14 Primary

  of the whole transmission and reception path, e.g. self-test loop-back · CPC title