Built-in testing signal wireless communication apparatus and testing method thereof

A wireless communication apparatus has: a direct current generator, for generating a direct current signal and a transmitter. The transmitter includes: an oscillating signal generator for generating an oscillating signal; a mixer for mixing one of the direct current signal and the transmitting signal with the oscillating signal according to a mode signal and generating a mixed signal; and an amplifying module for amplifying the mixed signal to generate an output signal. When the mode signal is represented that the wireless communication apparatus is under test, the direct current signal is being mixed with the oscillating signal and the mixed signal is a sinusoidal wave. When the mode signal is represented that the wireless communication apparatus is under transmitting, the transmitting signal is being mixed with the oscillating signal and the mixed signal is a modulated signal.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a testing method of a wireless communication apparatus, and more particularly, to a testing method of a wireless communication apparatus with a built-in testing signal.

2. Description of the Prior Art

In common radio frequency communication systems using amplitude modulation (AM), the linearity of the transceiver directly affects the quality of the received signal, which will be distorted by the noise inside or outside of the channel. Since the error-signal rate often increases with the signal distortion caused by non-linearity of the circuit, an external testing signal source is added and an oP1 dB (output 1 dB compression point) is observed when testing the transceiver IC. Please refer toFIG. 1.FIG. 1is a schematic diagram of delineating the output voltage as a function of the input voltage. In mass-production testing of the radio frequency IC, it is essential but time-consuming to measure the oP1 dB. As shown inFIG. 1, after sinusoidal signals with varied amplitude are inputted into the transceiver IC, the output voltage (Pout) is then obtained. It takes further calculation to get oP1 dB where the difference in Poutis 1 dB. In conclusion, with the fact that input of a sinusoidal signal with a varied voltage is inevitable in measuring Pout, a new method providing fast and simple measurement is required to decrease the time spent in measurement.

SUMMARY OF THE INVENTION

It is therefore one of the objectives of the present invention to provide a wireless communication apparatus with a built-in testing signal, and a testing method thereof, which will skip signal installation and save time spent in testing to solve the above-mentioned problems.

A wireless communication apparatus is disclosed, the apparatus comprising: a direct current generator, for generating a direct current signal; and a transmitter, coupled to the direct current generator, the transmitter comprising: an oscillating signal generator, for generating an oscillating signal; a mixer, coupled to the oscillating signal generator, for mixing one of the direct current signal and the transmitting signal with the oscillating signal according to a mode signal and generating a mixed signal; and an amplifying module, coupled to the mixer, for amplifying the mixed signal to generate an output signal; wherein when the mode signal is represented that the wireless communication apparatus is under test, the direct current signal is being mixed with the oscillating signal and the mixed signal is a sinusoidal wave; when the mode signal is represented that the wireless communication apparatus is under transmitting, the transmitting signal is being mixed with the oscillating signal and the mixed signal is a modulated signal.

A testing method for application in a wireless communication apparatus is disclosed, the method comprising: generating a direct current signal; generating an oscillating signal; mixing the direct current signal with the oscillating signal to generate a sinusoidal wave; and amplifying the sinusoidal wave and generating an output signal to be tested; wherein the direct current signal, the oscillating signal and the output signal are generated from the wireless communication apparatus.

DETAILED DESCRIPTION

Please refer toFIG. 2.FIG. 2is a functional block of a testing apparatus100according to an embodiment of the present invention. As shown inFIG. 2, the testing apparatus100includes a wireless communication apparatus110, a measuring device120and a spectrum analyzer130. As known in this field, a wireless communication apparatus is composed of a plurality of elements (a receiver or a transmitter). As shown inFIG. 2, the wireless communication apparatus110comprises a frequency synthesizer112for generating an oscillating signal, a mixer114for mixing input signals to generate a mixed signal, an amplifying module116for amplifying an input signal and a DC offset generator118for generating a direct current signal, wherein the frequency synthesizer112, the mixer114and the amplify module116form a transmitting circuit. The DC offset generator118is formed by a switch and controlled by a mode control signal. As the apparatus shown inFIG. 2, when the wireless communication apparatus110is under transmitting, the frequency synthesizer112outputs an oscillating signal to one end of the mixer114and the mode control signal closes the DC offset generator118. In one embodiment, the mode control signal is logic 1 which is representing the wireless communication apparatus110is under transmitting to close the switch. The mixer114mixes a transmitting signal with the oscillating signal to generate a modulated signal. Accordingly the modulated signal is amplified by the amplifying module116and generates an output signal to be transmitted. On the other hand, when the wireless communication apparatus110is under test, the frequency synthesizer112outputs an oscillating signal to one end of the mixer114and the mode control signal opens the DC offset generator118to generate a DC offset (supply voltage Vdd) to the other end of the mixer114. In one embodiment, the mode control signal is logic 0 which is representing the wireless communication apparatus110is under test to open the switch. The mixer114mixes the DC signal with the oscillating signal to generate a sinusoidal signal rather than generate a modulated signal, wherein the frequency of the sinusoidal signal is equal to the frequency of the oscillating signal generated by the frequency synthesizer112. Accordingly, the sinusoidal signal is amplified by the amplifying module116and generates an output signal to be tested. The measuring device120is coupled to the wireless communication apparatus100, for measuring if the power of the output signal is sufficient. The wireless communication apparatus100is qualified in measuring if the saturate power of the output signal is over the threshold value. According to one embodiment of the present invention, the threshold value could use the output voltage corresponding to the input voltage is 0 dbm as shown inFIG. 1. Moreover, the frequency of the output signal can be further used by the spectrum analyzer130to determine whether the frequency of the oscillating signal generated by the frequency synthesizer112is correct.

Please refer toFIG. 3.FIG. 3shows a flow chart of a testing method for the wireless communication apparatus according to the present invention. The testing method is operated on the testing apparatus100mentioned above, and comprises the following steps:

Step320: Output an oscillating signal to the mixer114.

Step330: Input a DC offset to the mixer114.

Step340: Amplify an output of the mixer114.

Step350: Measure an output of the amplifying module116and compare it with a threshold.

Step355: Is the output of the amplifying module116larger than the threshold? If yes, go to Step360; otherwise, go to Step370.

Step360: Analyze the output of the amplifying module116to determine whether or not the frequency of the oscillating signal generated by the frequency synthesizer112is correct.

Step365: Is the frequency spectrum correct? If yes, go to step380; otherwise, go to step370.

Step370: Determine the wireless communication apparatus does not pass the test.

Step380: Determine the wireless communication apparatus passes the test.

In this embodiment, after the synthesizer112is initiated (Step310), the synthesizer112will output an oscillating signal to the mixer114(step320). The DC offset generator118generates a DC offset (Step330) and transmits the DC offset to the other side of the mixer114. The DC offset is the maximum voltage of the communication system (i.e. Vdd) or the voltage corresponding to the input voltage is 0 dBm as shown inFIG. 1. The usage of the maximum voltage can ensure that the output signal of the wireless communication system is a saturated voltage or a maximum power. In this testing mode, after a large DC offset is generated by the built-in DC offset generator118and is transmitted to the mixer114, the measuring device120measures the output signal for determining whether the saturated voltage or the saturated power of the output signal is over a threshold to determine whether the wireless communication apparatus passes the test. As mentioned above, the oP1 dB and saturated power in each of wireless communication apparatus produced from the same process is supposed to be consistent. Therefore, the saturated power of the qualified wireless communication apparatus100can be used as the testing threshold for testing other wireless communication apparatuses. The method mentioned here will reduce the testing time and improve the efficiency of testing procedures.

On the other hand, the testing apparatus100further comprises a spectrum analyzer130, for determining the correctness of the frequency spectrum of the oscillating signal generated by the frequency synthesizer112(Step360). Generally speaking, the function of the mixer114in a communication system is to transform frequency, that is, signal multiplication. For example, the oscillating signal (i.e. a local oscillating signal) can be used to transform a median frequency signal to a radio frequency signal or transform a median frequency signal to a radio frequency signal. However, in this embodiment, one input end of the mixer114is not connected to any external signal source but a DC offset in testing mode, so the frequency of the median signal can be viewed as 0 Hz. That is, even mixing the DC offset with the oscillating signal, the frequency of the mixed signal outputted by mixed114is substantially equal to the frequency of the oscillating signal generated by synthesizer112. As a result, the spectrum shown on the spectrum analyzer130is corresponding to the spectrum of the oscillating signal. Therefore it is easy to verify the frequency of the oscillating signal is correct or not by utilizing the spectrum analyzer130.

The present invention utilizes a built-in DC offset generator to generate the DC testing signal to the mixer114, so the frequency of the oscillation signal can be verified without any external signal source. With this method, time spent in testing can be reduced. In addition, the determination of the threshold value is not limited to the embodiment mentioned above. Other ways to determine the threshold also lie within the scope of the present invention.