Testing circuit with directional coupler

1. A testing circuit comprising:

a testing circuit input configured to receive an output signal from a module, the output signal having a fundamental component and a harmonic component;

a testing circuit fundamental output configured to output the fundamental component;

a testing circuit harmonic output configured to output the harmonic component;

an insertion loss output configured to output an insertion loss output signal in response to an insertion loss input applied to the testing circuit fundamental output; and

a first directional coupler having a first coupler input coupled to the testing circuit input, a first transmitted output coupled to the testing circuit fundamental output, and a first coupled output coupled to the testing circuit harmonic output.

2. The testing circuit of claim 1 further comprising a first filter coupled between the first coupled output and the testing circuit harmonic output, the first filter configured to bandpass filter the harmonic component for a first type of the output signal.

3. The testing circuit of claim 2 wherein the first type of the output signal is a GSM (Global System for Mobile Communications) signal.

4. The testing circuit of claim 1 further comprising a second directional coupler having a second coupler input coupled to the testing circuit input, a second transmitted output coupled to the testing circuit fundamental output, and a second coupled output coupled to the testing circuit harmonic output.

5. The testing circuit of claim 4 further comprising a switch having a first switching input coupled to the first coupled output, a second switching input coupled to the second coupled output, and a switching output coupled to the testing circuit harmonic output.

6. The testing circuit of claim 4 further comprising a second filter coupled between the second coupled output and the testing circuit harmonic output, the second filter configured to bandpass filter the harmonic component for a second type of the output signal.

7. The testing circuit of claim 6 wherein the second type of the output signal is a DCS (Digital Cellular Service) signal.

8. The testing circuit of claim 1 wherein the first directional coupler includes a portion of a first trace and a portion of second trace, the first trace coupling the testing circuit input to the testing circuit fundamental output and the portion of the second trace being disposed adjacent and parallel to the portion of the first trace.

9. The testing circuit of claim 8 wherein the first trace and the second trace are disposed on a printed circuit board.

10. The testing circuit of claim 1 further comprising a first transmission signal input configured to provide a first transmission input signal to a first transmission input of the module.

11. The testing circuit of claim 10 further comprising a second transmission signal input configured to provide a second transmission input signal to a second transmission input of the module.

12. The testing circuit of claim 11 further comprising a switch having a first switching output coupled to the first transmission signal input and a second switching output coupled to the second transmission signal input.

13. A testing unit comprising:

a printed circuit board;

a testing circuit implemented on the printed circuit board, the testing circuit including a testing circuit input configured to receive an output signal from a radio-frequency (RF) module, the output signal having a fundamental component and a harmonic component, a testing circuit fundamental output configured to output the fundamental component, a testing circuit harmonic output configured to output the harmonic component, an insertion loss output configured to output an insertion loss output signal in response to an insertion loss input applied to the testing circuit fundamental output, and a first directional coupler having a first coupler input coupled to the testing circuit input, a first transmitted output coupled to the testing circuit fundamental output, and a first coupled output coupled to the testing circuit harmonic output.

14. The testing unit of claim 13 wherein the RF module is a front-end module (FEM).

15. The testing unit of claim 13 wherein the testing circuit further includes a second directional coupler having a second coupled input coupled to the testing circuit input, a second transmitted output coupled to the testing circuit fundamental output, and a second coupled output coupled to the testing circuit harmonic output.

16. The testing unit of claim 13 further comprising a second testing circuit implemented on the PCB, the second testing circuit including a second testing circuit input configured to receive a second output signal from a second module, the second output signal having a second fundamental component and a second harmonic component, a second testing circuit fundamental output configured to output the second fundamental component, a second testing circuit harmonic output configured to output the second harmonic component, and a second directional coupler having a second coupler input coupled to the second testing circuit input, a second transmitted output coupled to the second testing circuit fundamental output, and a second coupled output coupled to the second circuit harmonic output.

17. The testing unit of claim 13 wherein the first directional coupler includes a portion of a first trace and a portion of second trace, the first trace coupling the testing circuit input to the testing circuit fundamental output and the portion of the second trace being disposed adjacent and parallel to the portion of the first trace.

18. A method of testing a radio-frequency (RF) module, the method comprising:

coupling the RF module to a testing unit;

applying a transmission test input signal to an input of the testing unit;

receiving a transmission test fundamental output signal at a first output of the testing unit;

receiving a transmission test harmonic output signal from a second output of the testing unit via a directional coupler of the testing unit;

applying a reception test input signal to the first output of the testing unit; and

receiving a reception test output signal from an insertion loss output of the testing unit.

19. The method of claim 18 further comprising applying a second transmission test input signal to the input of the testing unit, the transmission test input signal being a GSM signal and the second transmission test input signal being a DCS signal.

20. The method of claim 18 wherein receiving the transmission test harmonic output signal comprises setting a state of a switch to receive a signal from one of a plurality of directional couplers corresponding to different signal types.