A radio frequency device comprising: a plurality of mixers (Rx1, Rx2, Rx3), each of the plurality of mixers having a first input terminal, a second input terminal, and an output terminal (IF1, IF2, IF3); and a self-test circuit comprising: a buffer having an input terminal and an output terminal, the buffer configured to buffer a reference signal from a local oscillator to produce a first RF signal at a first frequency; and a plurality of delay elements (TL1, TL2, TL3) having different respective transmission delays, the delay elements (TL1, TL2, TL3) each having a first end coupled to the output terminal of the buffer and a second end configured to provide a respective delayed signal based on the first RF signal, wherein the self-test circuit is configured to, in a test mode, couple the second ends of the delay elements (TL1, TL2, TL3) to respective first input terminals of the plurality of mixers (Rx1, Rx2, Rx3) to provide each mixer with the respective delayed signal, and wherein the second input terminals of the mixers (Rx1, Rx2, Rx3) are configured to receive a second RF signal having the first frequency, wherein the second RF signal is derived from the reference RF signal, wherein the self-test circuit is configured to, in a normal operation mode, couple a plurality of antenna ports to respective first input terminals of the plurality of mixers (Rx1, Rx2, Rx3), wherein the self-test circuit is configured to, in the test mode, change a phase shift of the buffer from a first value to a second value, in order to detect failure of the mixers. a plurality of mixers (Rx1, Rx2, Rx3), each of the plurality of mixers having a first input terminal, a second input terminal, and an output terminal (IF1, IF2, IF3); and a self-test circuit comprising: a buffer having an input terminal and an output terminal, the buffer configured to buffer a reference signal from a local oscillator to produce a first RF signal at a first frequency; and a plurality of delay elements (TL1, TL2, TL3) having different respective transmission delays, the delay elements (TL1, TL2, TL3) each having a first end coupled to the output terminal of the buffer and a second end configured to provide a respective delayed signal based on the first RF signal, wherein the self-test circuit is configured to, in a test mode, couple the second ends of the delay elements (TL1, TL2, TL3) to respective first input terminals of the plurality of mixers (Rx1, Rx2, Rx3) to provide each mixer with the respective delayed signal, and wherein the second input terminals of the mixers (Rx1, Rx2, Rx3) are configured to receive a second RF signal having the first frequency, wherein the second RF signal is derived from the reference RF signal, wherein the self-test circuit is configured to, in a normal operation mode, couple a plurality of antenna ports to respective first input terminals of the plurality of mixers (Rx1, Rx2, Rx3), wherein the self-test circuit is configured to, in the test mode, change a phase shift of the buffer from a first value to a second value, in order to detect failure of the mixers. a buffer having an input terminal and an output terminal, the buffer configured to buffer a reference signal from a local oscillator to produce a first RF signal at a first frequency; and a plurality of delay elements (TL1, TL2, TL3) having different respective transmission delays, the delay elements (TL1, TL2, TL3) each having a first end coupled to the output terminal of the buffer and a second end configured to provide a respective delayed signal based on the first RF signal, wherein the self-test circuit is configured to, in a test mode, couple the second ends of the delay elements (TL1, TL2, TL3) to respective first input terminals of the plurality of mixers (Rx1, Rx2, Rx3) to provide each mixer with the respective delayed signal, and wherein the second input terminals of the mixers (Rx1, Rx2, Rx3) are configured to receive a second RF signal having the first frequency, wherein the second RF signal is derived from the reference RF signal, wherein the self-test circuit is configured to, in a normal operation mode, couple a plurality of antenna ports to respective first input terminals of the plurality of mixers (Rx1, Rx2, Rx3), wherein the self-test circuit is configured to, in the test mode, change a phase shift of the buffer from a first value to a second value, in order to detect failure of the mixers.