Patent Description:
As the progress of the communication technology, mobile terminals, such as a cell phone, have become necessary in human life. More and more cell phones are equipped with a distance sensing function.

The distance sensing function could reduce the radiation to human bodies and reduce the power consumption of the mobile terminal. When the user is getting closer to the mobile terminal, the transmission function of the antenna is reduced to reduce the radiation to a human body. Therefore, most of the mobile terminals are equipped with the distance sensing function.

The distance sensing chip and the RF chip in a conventional mobile terminal are independently connected to their antennas. As shown in <FIG>, the distance sensing antenna is close to the RF antenna. Because both antenna are close to each other and are made by metal, they introduce interferences to each other. Furthermore, the occupied area of the distance sensing antenna is larger and the cost of the distance sensing antenna is higher.

D1 (<CIT>), D2 (<CIT>) and D3 (<CIT>) disclose examples of mobile terminals where distance sensing and RF communication chips are not independently connected to their antennas.

One objective of an embodiment of the present invention is to provide a mobile terminal with a shared antenna to solve the above-mentioned issues of high interferences and high costs in an improved way.

The invention is described below in detail with reference to the accompanying drawings, wherein like reference numerals are used to identify like elements illustrated in one or more of the figures thereof, and in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the particular embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Please refer to <FIG> is a diagram of a structure of a mobile terminal with a shared RF antenna according to an embodiment of the present invention. As shown in <FIG>, the mobile terminal comprises a printed circuit board (PCB) <NUM>. The PCB comprises a distance sensing module <NUM>, an RF module <NUM>, a filter module <NUM>, and an RF antenna module <NUM>. The distance sensing module <NUM> is electrically connected to the RF antenna module <NUM> through the filter module <NUM>. The RF antenna module <NUM> is electrically connected to the RF module <NUM>.

The RF antenna module <NUM> could generate a low-frequency resonant frequency (determined by the working frequency of the distance sensing module) and a high-frequency resonant frequency (corresponding to the working frequency of the RF module <NUM>) such that the RF antenna module <NUM> could satisfy the demands of a low-frequency working signal required by the distance sensing module <NUM> and a high-frequency working signal required by the high-frequency RF module <NUM>. The filter module <NUM> is used to block the unwanted portion of the input signal of the distance sensing module <NUM>. While the mobile terminal is working in a communication mode, the RF antenna module <NUM> generates a working signal. The working signal is transmitted to the RF module <NUM> and the filter module <NUM>. The RF module <NUM> receives the working signal and works accordingly. The filter module <NUM> receives the working signal and filters out the high-frequency portion of the working signal. For example, the filter module <NUM> could filter out the portion having frequency larger than <NUM> and only allow the signal having the frequency lower than <NUM> to pass through. The filtered working signal is then transmitted to the distance sensing module <NUM> as its input signal such that the distance sensing module <NUM> works accordingly. In this way, it could prevent the distance sensing module <NUM> from being incorrectly triggered. It could also ensure that the distance sensing module <NUM> could correctly be triggered when the distance sensing operation is required. The distance sensing module <NUM> is used to perform the distance sensing operation. The RF module <NUM> is used to perform a RF transceiving operation.

Furthermore, the mobile terminal could be a LTE, <NUM> or <NUM> wireless communication smart terminals having the distance sensing function, such as a tablet, a cell phone, a data card, etc. These belong to the scope of the present invention.

In this embodiment, the RF antenna module <NUM> and the filter module <NUM> capable of generating high-frequency and low-frequency resonant frequencies are adopted. This reduces the interferences between the distance sensing module <NUM> and the RF module <NUM> when they share the same antenna. Because only one shared antenna is used, the number of antennas is reduced and thus the cost is reduced. Furthermore, the above-mentioned issue of interferences is also solved.

Please refer to <FIG> in conjunction with <FIG>. In order to allow only the necessary working signal for the distance sensing module <NUM> (filter out the unwanted portion), the filter module comprises the first resistor R1, the first capacitor C1 and the first inductor L1. One end of the first resistor R1 is electrically connected to the RF antenna module <NUM> and the other end of the first resistor R1 is electrically connected to the ground through the first capacitor C1 and is also electrically connected to the distance sensing module <NUM> through the first inductor L1.

Specifically, the first resistor R1 connects the distance sensing module <NUM> to the RF antenna module <NUM> to realize the share of antenna. The first inductor L1 is used to block high-frequency portions and allow the low-frequency portion (such as signals having a frequency lower than <NUM>) to pass through. The first capacitor C1 is a filter capacitor for filtering out signals having a frequency higher than <NUM>. When the mobile terminal is working in the communication mode and the communication signals are inputted from the RF antenna module <NUM> into the distance sensing module <NUM>, the communication signals are released to the ground through the first resistor R1 and the first capacitor and the high-frequency portion (higher than <NUM>) of the communication signals are blocked by the first inductor L1 to prevent the distance sensing module from being incorrectly triggered. When the distance sensing module <NUM> needs to work, a low frequency signal is inputted the distance sensing module <NUM> through the first resistor R1 and the first inductor L1 to trigger the distance sensing module <NUM>.

Through installing the filter module <NUM>, when the mobile terminal is working in the communication mode, the communication signal is released to the ground and the signal having the frequency higher than <NUM> is blocked. This prevents the distance sensing module from being incorrectly triggered. When the distance sensing module <NUM> needs to work, the filter module <NUM> could allow the low-frequency signal to pass through the filter module to trigger the distance sensing module <NUM> to work. In this way, there is no need to add another distance sensing antenna. Therefore, the cost is reduced and the interference between two antennas is avoided.

In a preferred embodiment, the inductance of the first inductor L1 is 39nh-100nh. This inductance is not too low to affect the RF signal and is not too high to affect the distance sensing function. Thus, this inductance range could ensure the function of the filter module <NUM>.

Please refer to <FIG> and <FIG> again. The RF antenna module <NUM> comprises an RF antenna ANT and the second resistor R2. The end of the RF antenna ANT is electrically connected to the ground through the second resistor R2 and is electrically connected to one end of the first resistor R1. The second resistor R2 is used for protection. The RF antenna module <NUM> could generate the resonant frequency for the distance sensing module <NUM> to work and could also generate the resonant frequency for the RF module <NUM> to work. In other words, the RF antenna module <NUM> could satisfy the requirement of the distance sensing signal of the distance sensing module <NUM> and the requirement of the RF signal of the RF module <NUM>. The end of the RF antenna ANT has an antenna feeding point, which is electrically connected to the RF module <NUM> and the filter module <NUM> to ensure the communication signal to pass.

Please refer to <FIG> and <FIG> again. The RF module <NUM> comprises the RF chip U1, the third resistor R3, the fourth resistor R4 and the second capacitor C2. One end of the third resistor R3 is electrically connected to the end of the RF antenna ANT. The other end of the third resistor R3 is electrically connected to the ground through the second capacitor C2 and is also electrically connected to the signal pin of the RF chip U1 through the fourth resistor R4. The GND pin of the RF chip U1 is electrically connected to the ground. The third resistor R3 and the second capacitor C2 form the RC oscillator circuit for the filter function. The fourth resistor R4 is a protection resistor. The RF chip could be the RF chip of the model type RF1662. This model type has advantages of stable performance and great function. In another embodiment, the present invention could adopt another model type of the RF chip. This change also falls within the scope of the present invention.

When the mobile terminal is working in the communication mode, the RF antenna module <NUM> generates the communication signal. The RC oscillator circuit performs the filter operation on the communication signal and then transfers the filtered signal to the RF chip U1 to drive the RF chip U1 to work such that various RF functions are realized.

Please refer to <FIG> and <FIG> again. The distance sensing module <NUM> comprises the distance sensing chip U2, the fifth resistor R5, the sixth resistor R6, and the third capacitor C3. One end of the fifth resistor R5 is electrically connected to the other end of the first resistor R1 through the first inductor L1. The other end of the fifth resistor R5 is electrically connected to the ground through the third capacitor C3 and is electrically connected to an RX pin of the distance sensing chip U2 through the sixth resistor R6. The GND pin of the distance sensing chip U2 is electrically connected to the ground and the VDD pin of the distance sensing chip U2 is electrically connected to a <NUM>. 3V voltage source. The fifth resistor R5 and the third capacitor C3 form an RC oscillator circuit to perform the filter function. The sixth resistor R6 is the protection resistor. The distance sensing chip U2 could be the distance sensing chip of the model type LDJ18829M24AC002. This model type has advantages of stable performance and great function. In another embodiment, the present invention could adopt another model type of the distance sensing chip. This change also falls within the scope of the present invention.

When the mobile terminal is working in the communication mode, the communication signal is released to the ground through the filter module <NUM> and the signals having the frequency higher than <NUM> to prevent the distance sensing function from being incorrectly triggered. When the distance sensing module needs to work, the filter module <NUM> could allow the low-frequency signal to pass through the filter module <NUM>. The RC oscillator circuit performs the filter operation on the communication signal and transfers the filtered signal to the distance sensing chip U2 to drive the distance sensing chip U2 to work such that the distance sensing function is triggered.

In a further embodiment, the first resistor R1 is installed near the antenna feeding point. The first inductor L1 is installed near the distance sensing chip U2. This could ensure the filter module <NUM> to correctly work and prevent the interference between the devices. In this way, the distance sensing function and the RF function could be satisfied by sharing only one antenna. In addition, the layout wire is shorter on the PCB such that the influence on the RF and low frequency band is avoided.

In order to well understand the present application, a further illustration will be disclosed in the following disclosure along with <FIG> and <FIG>:.

The RF antenna module <NUM> generates the working signal when the mobile terminal is working in the communication mode. The working signal is respectively transmitted to the RF module <NUM> and the filter module <NUM>. The RF module <NUM> receives the working signal and works accordingly. The filter module <NUM> receives the working signal and filters out a high frequency portion from the working signal (e.g. filter out the signal portion having the frequency higher than <NUM> and allow the signal portion having the frequency lower than <NUM> to pass). This prevents the distance sensing module from being incorrectly triggered. When the distance sensing module needs to work, the low frequency signal that passes through the filter module <NUM> could drive the distance sensing chip U2 to work such that the distance sensing function is triggered.

Claim 1:
A mobile terminal with a shared radio frequency, RF, antenna, comprising:
a printed circuit board, PCB, (<NUM>), comprising:
a distance sensing module (<NUM>), configured to perform a distance sensing operation;
a radio frequency, RF, module (<NUM>), configured to perform an RF transceiving operation;
a filter module (<NUM>), configured to filter out a unwanted portion of an input signal of the distance sensing module (<NUM>); and
wherein the mobile terminal comprises an radio frequency, RF, antenna module (<NUM>), electrically connected to the distance sensing module (<NUM>) through the filter module (<NUM>) and directly connected to the RF module (<NUM>), the RF antenna module (<NUM>) being configured to generate a resonant frequency for the distance sensing module (<NUM>) and a resonant frequency for the RF module (<NUM>);
wherein the filter module (<NUM>) comprises:
a first resistor (R1);
a first capacitor (C1); and
a first inductor (L1);
wherein one end of the first resistor (R1) is electrically connected to the RF antenna module (<NUM>), and another end of the first resistor (R1) is electrically connected to a ground through the first capacitor (C1) and is electrically connected to the distance sensing module (<NUM>) through the first inductor (L1);
wherein the RF antenna module (<NUM>) comprises:
an RF antenna (ANT); and
a second resistor (R2);
wherein an end of the RF antenna (ANT) is electrically connected to the ground through the second resistor (R2) and is electrically connected to the end of the first resistor (R1);
wherein the distance sensing module (<NUM>) comprises:
a distance sensing chip (U2);
a fifth resistor (R5);
a sixth resistor (R6); and
a third capacitor (C3);
wherein one end of the fifth resistor (R5) is electrically connected to the another end of the first resistor (R1) through the first inductor (L1), another end of the fifth resistor (R5) is electrically connected to the ground through the third capacitor (C3) and is electrically connected to an RX pin of the distance sensing chip (U2) through the sixth resistor (R6), a GND pin of the distance sensing chip (U2) is electrically connected to the ground, and a VDD pin of the distance sensing chip (U2) is electrically connected to a <NUM>.3V voltage source.