Radiofrequency integrated circuit and corresponding test method

1. A radiofrequency transmission and/or reception integrated circuit comprising:

at least one radiofrequency signal amplifier, said at least one radiofrequency signal amplifier being configured, in operational mode, so as to perform a function of amplifying a first radiofrequency signal applied at an input, said at least one radiofrequency signal amplifier being configured so as to perform an oscillator function in a self-test mode of the integrated circuit, to generate a second radiofrequency signal on at least one of the input or an output of said at least one radiofrequency signal amplifier,

wherein the integrated circuit is configured, in said self-test mode, so as to allow said second radiofrequency signal to propagate in at least one component of said radiofrequency integrated circuit, separate from said at least one radiofrequency signal amplifier, and in that it also comprises a measuring circuit for measuring a signal generated following propagation of said second radiofrequency signal in said component of said integrated circuit and representative of at least one characteristic of said component, said at least one radiofrequency signal amplifier comprises a field-effect transistor controlled as a switch by an operating mode control signal, said switch forming a feedback loop between two nodes of the at least one radiofrequency signal amplifier and a node coupled to its input, said loop being open, corresponding to a blocked mode of said transistor, in operational mode, and closed, corresponding to a conductive mode of said transistor, in self-test mode.

2. The integrated circuit according to claim 1 , wherein said measuring circuit is a measuring circuit for measuring a low-frequency characteristic of said second radiofrequency signal.

3. The integrated circuit according to claim 2 , wherein said at least one measuring circuit is a peak voltage measuring circuit.

4. The integrated circuit according to claim 1 , comprising a reception path having at least one first amplifier stage and a transmission path having at least one last amplifier stage, wherein said at least one radiofrequency signal amplifier is the first amplifier stage of the reception path or the last amplifier stage of the transmission path and is coupled, via its input or its output, to an antenna connection pad.

5. The integrated circuit according to claim 1 , wherein said at least one radiofrequency signal amplifier is a differential-pair amplifier and comprises a feedback loop comprising a transistor controlled as a switch associated with each of inverting and non-inverting outputs of a stage, wherein said transistor controlled as a switch forms a Neutrodyne capacitor in operational mode and a short-circuit in self-test mode of the integrated circuit, then configuring said at least one radiofrequency signal amplifier as an electronic oscillator.

6. The integrated circuit according to claim 1 , wherein said at least one radiofrequency signal amplifier is a non-differential amplifier and comprises:

a first field-effect transistor in a common source configuration and a gate electrode of which forms a signal input of the at least one radiofrequency signal amplifier, in series with a second field-effect transistor of which a drain electrode forms a signal output node of the at least one radiofrequency signal amplifier,

a resonant circuit (for tuning a load of the output node, comprising two capacitors in series, and

a feedback loop controlled by the operating mode control signal, comprising a field-effect transistor controlled as a switch connected between a connection node between said first and second field-effect transistors and a connection node between the two capacitors.

7. The integrated circuit according to claim 1 , comprising a reception path having at least one first amplifier stage and one transmission path having at least one last amplifier stage, wherein said first amplifier stage (LNA 1 ) of the reception path and said last amplifier stage of the transmission path each have an amplification function in operational mode and an oscillator function in self-test mode of the integrated circuit, controlled by a respective mode control signal.

8. The integrated circuit according to claim 7 , furthermore comprising loopback means for looping an output of the transmission path back to an input of the reception path and at least one measuring circuit for measuring a low-frequency characteristic of the signal at the output of the reception path.

9. The integrated circuit according to claim 8 , furthermore comprising loopback means for looping an output of the reception path back to an input of the transmission path and a measuring circuit for measuring a low-frequency characteristic of the signal measured at the output of the transmission path.

10. The integrated circuit according to claim 1 , wherein the measuring circuit or circuits for measuring a low-frequency characteristic comprise a peak voltage detection circuit associated with a respective or shared analogue-to-digital converter.

11. A self-test method for a radiofrequency integrated circuit comprising the following steps:

a) configuring a radiofrequency signal amplifier in operational mode, so as to perform a function of amplifying a first radiofrequency signal applied at an input, said radiofrequency signal amplifier being configured so as to perform an oscillator function in a self-test mode of the integrated circuit, to generate a second radiofrequency signal on at least one of the input or an output of said radiofrequency signal amplifier, wherein the integrated circuit is configured, in said self-test mode, so as to allow said second radiofrequency signal to propagate in at least one component of said radiofrequency integrated circuit, separate from said radiofrequency signal amplifier, and in that it also comprises a measuring circuit for measuring a signal generated following propagation of said second radiofrequency signal in said component of said integrated circuit and representative of at least one characteristic of said component, said radiofrequency signal amplifier comprises a field-effect transistor controlled as a switch by an operating mode control signal, said switch forming a feedback loop between two nodes of the radiofrequency signal amplifier and a node coupled to its input, said loop being open, corresponding to a blocked mode of said transistor, in operational mode, and closed, corresponding to a conductive mode of said transistor, in self-test mode;

b) propagating said radiofrequency signal in at least one component of said radiofrequency integrated circuit, separate from said radiofrequency signal amplifier; and

c) measuring a signal generated following propagation of said radiofrequency signal in said component of said integrated circuit, and deducing at least one characteristic of said component therefrom.

12. The method according to claim 11 , wherein step c) comprises measuring a low-frequency characteristic of said radiofrequency signal.

13. The method according to claim 12 , wherein step c) also comprises determining a load impedance of the radiofrequency signal amplifier when its input or its output is connected to an antenna or to an equivalent impedance load.

14. The method according to claim 11 , wherein the integrated circuit comprises a reception path having at least one first amplifier stage and a transmission path having at least one last amplifier stage, wherein said radiofrequency signal amplifier is the first amplifier stage of the reception path or the last amplifier stage of the transmission path and is coupled, via its input or its output, to an antenna connection pad; the method comprising an antenna connection test step comprising:

connecting an antenna or an equivalent impedance load to said antenna connection pad,

activating a control signal, in order to control reconfiguration of an amplifier stage coupled to said antenna pad, which is the first amplifier stage of the reception path or the last amplifier stage of the transmission path, as an electronic oscillator, and

measuring a low-frequency characteristic of a signal measured between said at least one amplifier stage and said antenna connection pad, representative of an antenna load impedance, in order to discriminate between a correct and an incorrect antenna connection.

15. The method according to claim 11 , the radiofrequency integrated circuit comprising a transmission path having at least one last amplifier stage able to be reconfigured as an electronic oscillator, and the radiofrequency integrated circuit furthermore comprises first loopback means for looping back the output of said last amplifier stage of the transmission path at the input of said at least one amplifier stage of a reception path, and a measuring circuit for measuring a low-frequency characteristic of the measured signal on an output of the reception path, the test method furthermore comprising a step of checking a reception path (TEST-RX), comprising the following steps:

activating a control signal in order to control reconfiguration of said last amplifier stage of the transmission path as an electronic oscillator, in order to generate a sinusoidal radiofrequency calibration signal at output,

activating said first loopback means in order to inject said radiofrequency calibration signal at input of said at least one amplifier stage of the reception path, and

measuring a low-frequency characteristic of said radiofrequency calibration signal and a corresponding signal delivered at output of the reception path, in order to establish a reception path gain.

16. The method according to claim 15 , comprising an additional step of spectral analysis of the signal delivered at output of the reception path, in order to establish a noise level of the reception path.

17. The method according to claim 11 , the radiofrequency integrated circuit comprising a reception path having at least one first amplifier stage able to be reconfigured as an electronic oscillator, and the radiofrequency integrated circuit furthermore comprises second loopback means for looping back an output of the reception path to an input of a transmission path, the self-test method furthermore comprising a step of checking a transmission path, comprising the following steps:

activating a control signal in order to control reconfiguration of said first amplifier stage of the transmission path as an electronic oscillator, in order to generate a radiofrequency sinusoidal signal in said reception path and obtain a radiofrequency calibration signal at the output of said path,

activating said second loopback means in order to inject said radiofrequency calibration signal at the input of the transmission path, and

measuring a low-frequency characteristic of said radiofrequency calibration signal and a corresponding signal delivered at the output of the transmission path, in order to establish a transmission path gain.