CN112491436A

CN112491436A - Radio frequency circuit

Info

Publication number: CN112491436A
Application number: CN201910864370.2A
Authority: CN
Inventors: 陈家源; 陈志龙; 张家润; 王柏之
Original assignee: Realtek Semiconductor Corp
Current assignee: Realtek Semiconductor Corp
Priority date: 2019-09-12
Filing date: 2019-09-12
Publication date: 2021-03-12
Anticipated expiration: 2039-09-12
Also published as: CN112491436B

Abstract

An RF circuit capable of performing an RF characteristic test in a test mode, comprising: a test signal generator for generating a test signal in the test mode; a radio frequency receiver coupled to the test signal generator for transmitting the test signal to generate a receiver analog signal; a coupling circuit, for conducting in the test mode and not conducting in an operation mode, for transmitting the receiver analog signal to a radio frequency transmitter in the test mode; the radio frequency transmitter is used for transmitting the receiver analog signal to generate a transmitter analog signal; a test result generator, coupled between the rf transmitter and a test result output terminal, comprising a signal converter, the signal converter being configured to generate a conversion signal according to the transmitter analog signal in the test mode, an output signal of the test result output terminal being the conversion signal or derived from the conversion signal, the output signal representing a result of the rf characteristic test.

Description

Radio frequency circuit

Technical Field

The present invention relates to radio frequency circuits, and more particularly, to radio frequency circuits capable of performing radio frequency characteristic tests.

Background

The pure radio frequency circuit does not include a digital base frequency circuit, an analog-to-digital converter and a digital-to-analog converter, so that the radio frequency characteristic of the pure radio frequency circuit (bare Chip) cannot be measured through a Chip/Die Probing test in the prior art, and an instrument for the bare Chip Probing test is a low-order test instrument, is mostly used for measuring a direct current characteristic, and cannot be used for measuring the radio frequency characteristic. In view of the above, in the prior art, after the package of the rf-only circuit is completed, the rf-only circuit (package circuit) is tested by the apparatus including the adc and the dac to eliminate the problem; however, if the RF characteristic test can be performed on the bare die of the RF circuit, the problem can be eliminated in advance, so as to reduce the packaging and testing cost.

Disclosure of Invention

It is an objective of the claimed invention to provide a radio frequency circuit capable of performing a radio frequency characteristic test without any analog-to-digital converter and digital-to-analog converter, and without an external high-specification radio frequency transceiver.

The radio frequency circuit of the present invention is capable of performing a radio frequency characteristic test in a test mode without any adc and dac nor external high-specification rf transceiver, and an embodiment of the radio frequency circuit includes: a test signal generator for generating a test signal in the test mode; a radio frequency receiver coupled to the test signal generator for transmitting the test signal to generate a receiver analog signal; a receiving switch for non-conducting in the test mode and conducting in an operation mode, the receiving switch being coupled between the radio frequency receiver and an analog signal input terminal, the analog signal input terminal being coupled to an analog-to-digital converter; a transmission switch for non-conducting in the test mode and conducting in the operation mode, the transmission switch being coupled between an analog signal output terminal for coupling to a digital-to-analog converter and a radio frequency transmitter; a coupling circuit, for conducting in the test mode and not conducting in the operation mode, for transmitting the receiver analog signal to the RF transmitter in the test mode; the radio frequency transmitter is used for transmitting the receiver analog signal to generate a transmitter analog signal; and a test result generator, coupled between the radio frequency transmitter and a test result output terminal, including a signal converter, the signal converter being configured to generate a conversion signal according to the transmitter analog signal in the test mode, an output signal of the test result output terminal being the conversion signal or derived from the conversion signal, the output signal representing a result of the radio frequency characteristic test.

Another embodiment of the rf circuit of the present invention comprises: a test signal generator for generating a test signal in the test mode; a radio frequency transmitter coupled to the test signal generator for transmitting the test signal to generate a transmitter analog signal; a coupling circuit, for conducting in the test mode and not conducting in an operation mode, for transmitting the transmitter analog signal to an RF receiver in the test mode; the radio frequency receiver is used for transmitting the transmitter analog signal to generate a receiver analog signal; a test result generator, coupled between the radio frequency receiver and a test result output terminal, including a signal converter, the signal converter being configured to generate a conversion signal according to the receiver analog signal in the test mode, an output signal of the test result output terminal being the conversion signal or derived from the conversion signal, the output signal representing a result of the radio frequency characteristic test; a receiving switch for non-conducting in the test mode and conducting in the operation mode, the receiving switch being coupled between the radio frequency receiver and an analog signal input terminal, the analog signal input terminal being coupled to an analog-to-digital converter; and a transmission switch for non-conducting in the test mode and conducting in the operation mode, the transmission switch being coupled between the radio frequency transmitter and an analog signal output terminal, the analog signal output terminal being coupled to a digital-to-analog converter.

The features, implementations, and technical advantages of the present invention are described in detail below with reference to the accompanying drawings.

Drawings

FIG. 1 shows an embodiment of a radio frequency circuit of the present invention;

FIG. 2 shows an embodiment of the RF receiver of FIG. 1;

FIG. 3 illustrates one embodiment of the RF transmitter of FIG. 1;

FIG. 4 shows one embodiment of the test result generator 170; and

fig. 5 shows another embodiment of the rf circuit of the present invention.

Description of the symbols

100 radio frequency circuit

110 test signal generator

120 radio frequency receiver

130 receiving switch

140 transfer switch

150 coupling circuit

160 radio frequency transmitter

170 test result generator

180T/R SW (radio frequency signal input/output circuit)

PAD_OUTTest result output terminal

RF_IN/OUTTransmitting terminal

RX_{ADC_IN}Analog signal input terminal

TX_{DAC_OUT}Analog signal output terminal

S_TTest signal

RX_AReceiver analog signal

RX_A1Receiver analog signal

TX_ATransmitter analog signal

S_OUTOutput signal

210LNA (Low noise Amplifier)

220 buffer stage circuit

230 frequency mixer

240TIA (transimpedance amplifier)

250 filter

LO1 oscillating signal

S_{LOW_FREQ}Low frequency signal

310 filter

320 mixer

330 gain stage circuit

340PA (Power Amplifier)

LO2 oscillating signal

S_{HIGH_FREQ}High frequency signal

410 signal converter

420 buffer stage circuit

S_CONConverting signals

500 radio frequency circuit

510 test signal generator

520 radio frequency transmitter

530 coupling circuit

540 radio frequency receiver

550 test result generator

560 receiving switch

570 transfer switch

580T/R SW (radio frequency signal input/output circuit)

Detailed Description

The invention discloses a radio frequency circuit which can execute radio frequency characteristic test without any analog-to-digital converter, digital-to-analog converter and external high-specification radio frequency transceiver.

Fig. 1 shows an embodiment of the rf circuit of the present invention. The rf circuit 100 of fig. 1 is capable of performing an rf characteristic test in a test mode, and includes a test signal generator 110, an rf receiver 120, a receiving switch 130, a transmitting switch 140, a coupling circuit 150, an rf transmitter 160, a test result generator 170, and an rf signal input/output circuit (T/R SW) 180. In this embodiment, the rf circuit 100 is an unpackaged die (die), and the rf characteristic test is a Chip Probing test; however, this is not a limitation of the practice of the present invention.

Please refer to fig. 1. The test signal generator 110 is used in the test modeGenerating a test signal S_T. One embodiment of the test signal generator 110 comprises a single-frequency (single-tone) signal generator for generating a single-frequency signal as the test signal S_T(ii) a For example, the single frequency signal generator comprises a phase-locked loop, which generates a clock signal as the test signal S according to a reference clock_T. The test signal S_TThe characteristics (e.g., frequency and strength) of the test signal generator 110 may depend on implementation requirements (e.g., the location of the test signal generator 110 in the rf circuit 100).

Please refer to fig. 1. The RF receiver 120 is coupled to the test signal generator 110 for transmitting the test signal S_TTo generate a receiver analog signal RX_A. Fig. 2 shows an embodiment of the rf receiver 120, which includes a Low Noise Amplifier (LNA) 210, a buffer circuit 220 (e.g., a LNA), a mixer 230, a Transimpedance Amplifier (TIA) 240, and a filter 250, wherein each of the buffer circuit 220, the Transimpedance Amplifier 240, and the filter 250 may be optionally omitted, and other circuits may be optionally included in the rf receiver 120 according to implementation requirements. In one exemplary embodiment, the test signal generator 110 outputs the test signal S_TTo a node between the lna 210 and the mixer 230, such that the mixer 230 is in the test mode according to a local oscillator signal LO1 and the test signal S_TGenerating a low frequency signal S_{LOW_FREQ}The receiver simulates a signal RX_AIs the low frequency signal S_{LOW_FREQ}Or from the low-frequency signal S_{LOW_FREQ}(e.g., the output of transimpedance amplifier 240 or filter 250); however, the test signal generator 110 can output the test signal S as long as the implementation is feasible_TAny point in the transmission path to the rf receiver 120, such as a location between the low noise amplifier 210 and the rf signal input/output circuit 180, or a location between the mixer 230 and the receiving switch 130. It is noted that in the embodiment of fig. 2, the signal between the mixer 230 and the rf signal input/output circuit 180 may be a common two-terminal signal, the mixer 230 and the receiving switch 13The signals between 0 include an In-Phase signal (In-Phase signal) and a Quadrature-Phase signal (Quadrature-Phase signal), which are well known In the art, and the details thereof are omitted herein.

Please refer to fig. 1. The receiving switch 130 is used for being non-conductive in the test mode and conductive in an operation mode; the receiving switch 130 is coupled to the RF receiver 120 and an analog signal input terminal RX_{ADC_IN}The analog signal input terminal RX_{ADC_IN}For coupling with an analog-to-digital converter. The transmission switch 140 is used for being non-conductive in the test mode and conductive in the operation mode; the transmission switch 140 is coupled to an analog signal output terminal TX_{DAC_OUT}And a radio frequency transmitter 160, the analog signal output terminal TX_{DAC_OUT}For coupling a digital-to-analog converter. A coupling circuit 150 (e.g., a transmission line including a switch) for conducting in the test mode and not conducting in the operation mode to simulate the receiver with the signal RX in the test mode_ATransmitted to the RF transmitter 160, and to avoid confusion, the receiver analog signal received by the RF transmitter 160 is called RX_A1. In the embodiment of fig. 1, one end of the coupling circuit 150 is coupled between the rf receiver 120 and the receiving switch 130, and the other end is coupled between the transmitting switch 140 and the rf transmitter 160; however, both ends of the coupling circuit 150 can be coupled to any place of the transmission path of the rf receiver 120 and any place of the transmission path of the rf transmitter 160, respectively, as long as the implementation is feasible. For example, the coupling circuit 150 includes a first terminal and a second terminal; the first terminal is coupled between a mixer (e.g., the mixer 230 of fig. 2) and a filter (e.g., the filter 250 of fig. 2) of the rf receiver 120, or between the filter (e.g., the filter 250 of fig. 2) and the receiving switch 130; the second terminal is coupled between a mixer (e.g., the mixer 320 of fig. 3) and a filter (e.g., the filter 310 of fig. 3) of the rf transmitter 160, or between the filter and the transmit switch 140.

Please refer to fig. 1. The RF transmitter 160 is used to transmit the receiver analog signal RX_A1To generate a transmitter analog signal TX_A. Fig. 3 shows an embodiment of the rf transmitter 160, which includes a filter 310, a mixer 320, a gain stage 330 (e.g., a pre-driver Amplifier (PAD)), and a Power Amplifier (PA) 340, wherein each of the filter 310 and the gain stage 330 may be optionally omitted, and other circuits may be optionally included in the rf transmitter 160. In an exemplary embodiment, one end of the coupling circuit 150 is coupled to a node between the filter 310/transmission switch 140 and the mixer 320 to output the receiver analog signal RX_A1To the node, so that the mixer 320 is in the test mode according to a local oscillator signal LO2 and the receiver analog signal RX_A1Generating a high frequency signal S_{HIGH_FREQ}The transmitter analog signal TX_AFor the high frequency signal S_{HIGH_FREQ}Or from the high-frequency signal S_{HIGH_FREQ}(e.g., the output signal of gain stage circuit 330). In an exemplary embodiment, the test result generator 170 is coupled to a node between the gain stage 330 and the power amplifier 340 for receiving the transmitter analog signal TX therefrom_AAnd accordingly generates an output signal S_OUT(ii) a However, the test result generator 170 may be coupled to any position of the transmission path of the rf transmitter 160, such as a position between the power amplifier 340 and the rf signal input/output circuit 180, or a position between the mixer 320 and the gain stage circuit 330, as long as the implementation is feasible. It is noted that the aforementioned test signal S_TMay be selectively different from the frequency of the second local oscillator signal LO2 (e.g., 2.4GHz) depending on implementation requirements. It is noted that in the embodiment of fig. 3, the signals between the mixer 320 and the rf signal input/output circuit 180 may be two-terminal signals, and the signals between the mixer 320 and the transmission switch 140 include an in-phase signal and a quadrature-phase signal, which are well known in the art and the details of which are omitted herein.

Please refer to fig. 1. The test result generator 170 is coupled to the RF transmitter 160 and a test result output PAD_OUTIn the meantime. FIG. 4 shows the test result generator 170One embodiment includes a signal converter 410 and a buffer stage circuit 420 (e.g., amplifier), wherein the buffer stage circuit 420 may be optionally omitted depending on implementation requirements. The signal converter 410 is used for converting the transmitter analog signal TX in the test mode_AGenerating a switching signal S_CONThe test result output terminal PAD_OUTIs output signal S_OUTFor the converted signal S_CONOr from the converted signal S_CON(e.g., the output signal of the buffer stage circuit 420), the output signal S_OUTRepresenting the results of the radio frequency characterization test. In one exemplary embodiment, the signal converter 410 comprises one of the following circuits: a self-mixer (self-mixer) for mixing the analog signal TX of the transmitter_AOutputting a voltage strength value as the conversion signal S_CON(ii) a A known or self-developed root-mean-square (RMS) value detector for simulating a signal TX based on the transmitter_AOutputting a voltage root mean square value as the conversion signal S_CON(ii) a A known or self-developed average value detector for outputting a voltage average value as the conversion signal according to the transmitter analog signal; and a known or self-developed power detector for detecting the transmitter analog signal TX_AOutputting a power value as the converted signal S_CON. Notably, due to the test signal S_TIs controllable and the test signal S_TIs known, the output signal S_OUTIs predictable, e.g. the average level at the instant or over a period of time, so that the output signal S is determined_OUTIf the result is in accordance with the expectation, the result of the radio frequency characteristic test can be obtained.

Please refer to fig. 1. A radio frequency signal input/output circuit 180 (e.g., Circulator) is coupled between the RF receiver 120 and the RF transmitter 160 for transmitting a radio frequency signal via a receiving end RF in the operation mode_IN/OUTReceive a Radio Frequency (RF) reception signal from the antenna or output a RF transmission signal to the antenna. Since the rf signal input/output circuit 180 may be a known or self-developed technology, its details are omitted here.

Fig. 5 shows another embodiment of the rf circuit of the present invention. The rf circuit 500 of fig. 5 is capable of performing an rf characteristic test in a test mode, and includes a test signal generator 510, an rf transmitter 520, a coupling circuit 530, an rf receiver 540, a test result generator 550, a receiving switch 560, a transmitting switch 570, and an rf signal input/output circuit 580. In this embodiment, the rf circuit is an unpackaged die, and the rf characteristic test is a die probing test, which is not a limitation of the present invention.

Please refer to fig. 5. The test signal generator 510 is used for generating a test signal S in the test mode_T. The RF transmitter 520 is coupled to the test signal generator 510 for transmitting the test signal S_TTo generate a transmitter analog signal TX_A. The coupling circuit 530 is used for conducting in the test mode and not conducting in an operation mode to transmit the transmitter analog signal TX in the test mode_ATo an rf receiver 540. The RF receiver 540 is used to transmit the transmitter analog signal TX_ATo generate a receiver analog signal RX_A. The test result generator 550 is coupled to the RF receiver 540 and a test result output PAD_OUTIn the test mode, a signal converter is included for converting the analog signal RX according to the receiver analog signal RX_AGenerating a switching signal S_CON(ii) a Test result output terminal PAD_OUTAn output signal S of_OUTFor the converted signal S_CONOr from the converted signal S_CONThe output signal S_OUTRepresenting the results of the radio frequency characterization test. The receiving switch 560 is used to be non-conductive in the test mode and conductive in the operation mode; the receiving switch 560 is coupled to the RF receiver 540 and an analog signal input terminal RX_{ADC_IN}The analog signal input terminal RX_{ADC_IN}For coupling with an analog-to-digital converter. The pass switch 570 is used to be non-conductive in the test mode and conductive in the operation mode; the transmission switch 570 is coupled to the RF transmitter 520 and an analog signal output terminal TX_{DAC_OUT}The analog signal output terminal TX_{DAC_OUT}For coupling a digital-to-analog converter. The RF signal I/O circuit 580 is coupled between the RF receiver 540 and the RF transmitter 520 for RF transmission via a receiving end in the operating mode_IN/OUTReceive a Radio Frequency (RF) reception signal from the antenna or output a RF transmission signal to the antenna. Compared to fig. 1, the test signal generator 550 of the embodiment of fig. 5 outputs the test signal S_TTo the RF transmitter 520, and the test result generator 550 receives the receiver analog signal RX_AAnd accordingly generating the output signal S_OUT。

Please refer to fig. 1. In an exemplary embodiment, the RF receiver 540 (e.g., the RF receiver 120 of FIG. 2) includes a first mixer (e.g., the mixer 230 of FIG. 2) for generating the first local oscillator signal and the transmitter analog signal TX in the test mode_AGenerating a low frequency signal, the receiver simulating a signal RX_AIs the low frequency signal or is derived from the low frequency signal. In an exemplary embodiment, the rf transmitter 520 (e.g., the rf transmitter 160 of fig. 3) includes a second mixer (e.g., the mixer 320 of fig. 3) for generating the test signal S according to a second local oscillation signal in the test mode_TGenerating a high frequency signal, the transmitter analog signal TX_AIs the high frequency signal or is derived from the high frequency signal. In one exemplary embodiment, the coupling circuit 530 comprises a first terminal coupled between the rf signal input/output circuit 580 and the first mixer, and a second terminal coupled between the rf signal input/output circuit 580 and the second mixer; in another example, the first terminal is coupled between the first mixer and a low noise amplifier (e.g., the low noise amplifier 210 of fig. 2) of the rf receiver 540, and the second terminal is coupled between the second mixer and a power amplifier (e.g., the power amplifier 340 of fig. 3) of the rf transmitter 520; it is noted that, as long as the implementation is feasible, two ends of the coupling circuit 530 can be coupled to any of the transmission paths of the rf receiver 540 and the rf transmitter 520, respectivelyAny of the above. In an exemplary embodiment, the test result generator 550 (e.g., the test result generator 170 of FIG. 4) receives the receiver analog signal RX from a first node between the first mixer and a first filter (e.g., the filter 250 of FIG. 2) of the RF receiver 540_AOr receiving the receiver analog signal RX from a second node between the first filter and the receiving switch 560_A(ii) a However, the test result generator 550 may be coupled to any position of the transmission path of the RF receiver 540 as long as the implementation is feasible. In one exemplary embodiment, the test signal generator 510 outputs the test signal S_TTo a third node between a second filter (e.g., filter 310 of FIG. 3) of the RF transmitter 520 and the second mixer, or outputs the test signal S_TTo a fourth node between the second filter and the pass switch 570.

Since those skilled in the art can appreciate details and variations of the embodiment of fig. 5 with reference to the disclosure of the embodiment of fig. 1 to 4, that is, technical features of the embodiment of fig. 1 to 4 can be reasonably applied to the embodiment of fig. 5, repeated and redundant descriptions are omitted herein.

It should be noted that, when the implementation is possible, a person skilled in the art may selectively implement some or all of the technical features of any one of the foregoing embodiments, or selectively implement a combination of some or all of the technical features of the foregoing embodiments, thereby increasing the flexibility in implementing the invention.

In summary, the rf circuit of the present invention can perform the rf characteristic test without any adc and dac or external high-specification rf transceiver, so that the rf circuit of the present invention can receive the rf characteristic test in a bare die state, thereby saving the test cost and the unnecessary package cost.

Although the embodiments of the present invention have been described above, the embodiments are not intended to limit the present invention, and those skilled in the art can make variations on the technical features of the present invention according to the explicit or implicit contents of the present invention, and all such variations may fall within the scope of the patent protection sought by the present invention.

Claims

1. A radio frequency circuit capable of performing a radio frequency characteristic test in a test mode without an analog-to-digital converter and a digital-to-analog converter, the radio frequency circuit comprising:

a test signal generator for generating a test signal in the test mode;

a radio frequency receiver coupled to the test signal generator for transmitting the test signal to generate a receiver analog signal;

a receiving switch for non-conducting in the test mode and conducting in an operation mode, the receiving switch being coupled between the radio frequency receiver and an analog signal input terminal, the analog signal input terminal being coupled to an analog-to-digital converter;

a transmission switch for non-conducting in the test mode and conducting in the operation mode, the transmission switch being coupled between an analog signal output terminal for coupling to a digital-to-analog converter and a radio frequency transmitter;

a coupling circuit, for conducting in the test mode and not conducting in the operation mode, for transmitting the receiver analog signal to the RF transmitter in the test mode;

the radio frequency transmitter is used for transmitting the receiver analog signal to generate a transmitter analog signal; and

a test result generator coupled between the RF transmitter and a test result output, the test result generator comprising:

a signal converter for generating a conversion signal according to the transmitter analog signal in the test mode, wherein an output signal of the test result output terminal is the conversion signal or is derived from the conversion signal, and the output signal represents the result of the rf characteristic test.

2. The RF circuit of claim 1 wherein the RF receiver comprises a first mixer and a second mixer, the first mixer configured to generate a low frequency signal according to a first local oscillating signal and the test signal in the test mode, the receiver analog signal being the low frequency signal or derived from the low frequency signal, the second mixer configured to generate a high frequency signal according to a second local oscillating signal and the receiver analog signal in the test mode, the transmitter analog signal being the high frequency signal or derived from the high frequency signal.

3. The RF circuit of claim 1 wherein the coupling circuit includes a first terminal coupled between the RF receiver and the receive switch and a second terminal coupled between the transmit switch and the RF transmitter.

4. The RF circuit of claim 1 wherein the RF receiver comprises a first mixer and a first filter, the RF transmitter comprises a second mixer and a second filter, the first filter is between the first mixer and the receive switch, the second filter is between the second mixer and the transmit switch, the coupling circuit comprises a first terminal coupled between the first mixer and the first filter or between the first filter and the receive switch, and a second terminal coupled between the second mixer and the second filter or between the second filter and the transmit switch.

5. The radio frequency circuit of claim 1, further comprising a radio frequency signal input/output circuit coupled between the radio frequency receiver and the radio frequency transmitter, wherein the radio frequency receiver comprises a first mixer and a low noise amplifier, the radio frequency transmitter comprises a second mixer and a power amplifier, the low noise amplifier is coupled between the radio frequency signal input/output circuit and the first mixer, the power amplifier is coupled between the radio frequency signal input/output circuit and the second mixer, the test signal generator outputs the test signal to a first node between the low noise amplifier and the first mixer, the test result generator receives the transmitter analog signal from a second node between the second mixer and the power amplifier.

6. A radio frequency circuit capable of performing a radio frequency characteristic test in a test mode, the radio frequency circuit comprising:

a test signal generator for generating a test signal in the test mode;

a radio frequency transmitter coupled to the test signal generator for transmitting the test signal to generate a transmitter analog signal;

a coupling circuit, for conducting in the test mode and not conducting in an operation mode, for transmitting the transmitter analog signal to an RF receiver in the test mode;

the radio frequency receiver is used for transmitting the transmitter analog signal to generate a receiver analog signal;

a test result generator coupled between the RF receiver and a test result output, the test result generator comprising:

a signal converter for generating a conversion signal according to the receiver analog signal in the test mode, wherein an output signal of the test result output terminal is the conversion signal or is derived from the conversion signal, and the output signal represents the result of the radio frequency characteristic test;

a receiving switch for non-conducting in the test mode and conducting in the operation mode, the receiving switch being coupled between the radio frequency receiver and an analog signal input terminal, the analog signal input terminal being coupled to an analog-to-digital converter; and

a transmission switch for non-conducting in the test mode and conducting in the operation mode, the transmission switch being coupled between the radio frequency transmitter and an analog signal output terminal, the analog signal output terminal being coupled to a digital-to-analog converter.

7. The RF circuit of claim 6 wherein the RF receiver comprises a first mixer and a second mixer, the first mixer configured to generate a low frequency signal according to a first local oscillating signal and the transmitter analog signal in the test mode, the receiver analog signal being the low frequency signal or derived from the low frequency signal, the second mixer configured to generate a high frequency signal according to a second local oscillating signal and the test signal in the test mode, the transmitter analog signal being the high frequency signal or derived from the high frequency signal.

8. The RF circuit of claim 6 further comprising an RF signal I/O circuit coupled between the RF receiver and the RF transmitter, wherein the RF receiver comprises a first mixer and the RF transmitter comprises a second mixer, the coupling circuit comprises a first terminal coupled between the RF signal I/O circuit and the first mixer and a second terminal coupled between the RF signal I/O circuit and the second mixer.

9. The RF circuit of claim 6 further comprising an RF signal I/O circuit coupled between the RF receiver and the RF transmitter, wherein the RF receiver comprises a first mixer and a low noise amplifier, the RF transmitter comprises a second mixer and a power amplifier, the low noise amplifier is coupled between the RF signal I/O circuit and the first mixer, the power amplifier is coupled between the RF signal I/O circuit and the second mixer, the coupling circuit comprises a first terminal coupled between the first mixer and the low noise amplifier and a second terminal coupled between the second mixer and the power amplifier.

10. The RF circuit of claim 6 wherein the RF receiver includes a first filter and a first mixer, the RF transmitter includes a second filter and a second mixer, the first filter is between the receive switch and the first mixer, the second filter is between the transmit switch and the second mixer, the test result generator receives the receiver analog signal from a first node between the first mixer and the first filter or from a second node between the first filter and the receive switch, the test signal generator outputs the test signal to a third node between the second filter and the second mixer or to a fourth node between the second filter and the transmit switch.