CN1549647A - Double- mode diplex for mobile communication terminal - Google Patents

Abstract

A double mode duplexer is composed of separation switch of TV-SCDMA for separating transmission-receiving signal of TD-SCDMA, duplexer of GSM for separating transmission-receiving signal of GSM, switch being used to connect antenna on separation switching of TD-SCDMA and switching being used to connect antenna on duplexer of GSM.

Description

The double-mode duplexer of mobile communication terminal

Technical field

The invention relates to mobile communication terminal, especially relate to a kind of double-mode duplexer that is intended to improve receptivity.

Background technology

As a rule, mobile communication terminal has filters such as duplexer (duplexer), SAW, to realize the conversation of sound clarity.

Above-mentioned duplexer directly is connected with antenna, is bringing into play the effect that the frequency that enters by this antenna is replenished, and is also referred to as antenna multicoupler or diplexer.

That is, duplexer utilizes the difference of frequency, and tranmitting frequency is separated with receive frequency.Remove unwanted frequency simultaneously.

Fig. 1 is the circuit structure diagram of common double multiplexer.As shown in the figure, its emission constitutes with band pass filter (12) with band pass filter (11) and reception.

The effect of above-mentioned each band pass filter (11) (12) is that corresponding signal is passed through, and makes all the other signal attenuations.

Fig. 2 is the circuit structure diagram of GSM/TD-SCDMA double-mode duplexer in the past.As shown in the figure, it is made of following several sections: GSM/TD-SCDMA duplexer (20), it is connected in antenna, to (Global System for Mobile communication: transmitting and receiving signal global system for mobile communications) is with (Time Division-Synchronous Code Divion Multiple Access: transmitting and receiving signal TD SDMA) separates based on TD-SCDMA based on GSM; TD-SCDMA separating switch (21), it is connected in this duplexer (20), and the transmitting and receiving signal based on TD-SCDMA is separated; GSM duplexer (22), it is connected in above-mentioned duplexer (20), and the transmitting and receiving signal based on GSM is separated.

Usually, the receptivity of receiver can be according to following " mathematical expression 1 ", serves as according to estimating with the NF (noise factor) of receiving terminal.

" mathematical expression 1 "

P _{in_min}＝174dBm/Hz+NF+10logB+SNR _min

For the circuit of Fig. 2, the noise factor (NF) that comprises in above-mentioned " mathematical expression 1 " can be represented as " mathematical expression 2 " or " mathematical expression 3 ".

" mathematical expression 2 "

${\mathrm{NF}}_{\mathrm{total}}\≅{\mathrm{NF}}_{\mathrm{duplexer}\left(20\right)+\mathrm{switch}\left(21\right)}+\frac{{\mathrm{NF}}_{\mathrm{LNA}}-1}{G_{\mathrm{duplexer}}}$

" mathematical expression 3 "

${\mathrm{NF}}_{\mathrm{total}}\≅{\mathrm{NF}}_{\mathrm{duplexer}\left(20\right)+\mathrm{GSMduplexer}\left(22\right)}+\frac{{\mathrm{NF}}_{\mathrm{LNA}}-1}{G_{\mathrm{duplexer}}}$

Promptly, in the circuit of Fig. 2, the insertion loss of duplexer (20) (22) and switch (21) is equivalent to noise factor, for the TD-SCDMA pattern, the noise factor of duplexer (20) and switch (21) increases the overall noise coefficient of receiving terminal, for the GSM pattern, the noise factor of duplexer (20) (21) increases the overall noise coefficient of receiving terminal.

In addition, reach shown in " mathematical expression 3 " as " mathematical expression 2 ", overall noise coefficient (NF) is mainly determined by the performance of front end of receiving terminal.

But there is a kind of like this problem in conventional art, and promptly when using GSM pattern and TD-SCDMA pattern, GSM/TD-SCDMA increases the whole NF (noise factor) of system with the insertion loss of each filter that duplexer has, and has reduced receiver performance.

That is, conventional art needs switch (21) and duplexer (20) (22) in order to realize the double-mode duplexer of GSM/TD-SCDMA, thereby has increased the non-efficiency in space, has increased the noise factor of receiving terminal, and has reduced the isolation of GSM and TD-SCDMA.

Summary of the invention

Therefore, the present invention is for improving problem in the past, and purpose is to provide a kind of double-mode duplexer of mobile communication terminal, receives emission based on the required circuit of the signal of TD-SCDMA and GSM to constitute one, so that can improve the noise factor of receiving terminal, improve receiving sensitivity.

That is, the present invention is built in TD-SCDMA in the circuit with circuit and GSM/TD-SCDMA selector switch with circuit, GSM, so that can improve the noise factor of receiving terminal, improves receiving sensitivity.

For achieving the above object, feature of the present invention is that double-mode duplexer comprises following several sections: the TD-SCDMA separating switch is used to separate the TD-SCDMA transmitting and receiving signal; The GSM duplexer is used to separate the GSM transmitting and receiving signal; The GSM/TD-SCDMA selector switch is used for antenna is connected to above-mentioned TD-SCDMA with separating switch or GSM duplexer.

Above-mentioned TD-SCDMA is to substitute with duplexer to constitute with the feature of separating switch.

Description of drawings

Fig. 1 is the circuit diagram of common double multiplexer.

Fig. 2 is the duplexer circuit figure of conventional art.

Fig. 3 is the required duplexer circuit figure of one embodiment of the invention.

Fig. 4 is the required duplexer circuit figure of another embodiment of the present invention.

Fig. 5 and Fig. 6 are conventional art and receiver performance table of the present invention.

Embodiment

With reference to the accompanying drawings, describe the present invention in detail.

Fig. 3 is the required duplexer circuit figure of one embodiment of the invention.As shown in the figure, double-mode duplexer is made of following several sections: TD-SCDMA is used to separate the TD-SCDMA transmitting and receiving signal with separating switch (31); GSM is used to separate the GSM transmitting and receiving signal with duplexer (32); Switch (33) is used for antenna (35) is connected to above-mentioned TD-SCDMA separating switch (31); Switch (34) is used for antenna (35) is connected to said GSM duplexer (32).

The work and the action effect of the embodiments of the invention of structure describe to having as above below.

In an embodiment of the present invention, use on the duplexer (32) with separating switch (31) or GSM, have switch (33) (34) for antenna (35) being connected to TD-SCDMA.

So, when working with the TD-SCDMA pattern, starting switch (33), when working with the GSM pattern, starting switch (34).

That is, when opening switch (33) with the work of TD-SCDMA pattern, TD-SCDMA is connected to antenna (35) with separating switch (31).When emission TD-SCDMA signal, above-mentioned TD-SCDMA switches according to the TX-ON signal with separating switch (31), when receiving the TD-SCDMA signal, switches according to the RX-ON signal.At this moment, switch (34) keeps (off) state of cutting out.

On the contrary, when when opening switch (34) with the work of GSM pattern, GSM is connected to antenna (35) with duplexer (32).Said GSM utilizes 2 band pass filters to separate emission, received signal with duplexer (32).At this moment, switch (33) keeps (off) state of cutting out.

And in said process, switch (33,34) is with TD-SCDMA pattern or the work of GSM pattern the time, and a side switch switches to opening, and the opposite side switch keeps closed condition.

Therefore, the GSM/TD-SCDMA double-mode duplexer of the present invention by switch (31) (33) (34) and duplexer (32) constitute has abundant isolation between GSM frequency and TD-SCDMA frequency, suppressed the increase part of noise factor (NF).

That is, embodiments of the invention pass through to remove the GSM/TD-SCDMA duplexer (20) under the conventional art, thereby have improved noise factor (NF), and the improvement value is the insertion loss of this duplexer (20), is approximately about 1.5～3dB.

If the receiver performance among TD-SCDMA pattern comparison conventional art and the present invention sees Fig. 5 and Fig. 6 for details.As shown in the figure, when application is of the present invention, compare with conventional art, noise factor (NF) has improved about about 3dB.

In addition, as another embodiment of the present invention, can constitute by circuit as shown in Figure 4.

That is, have TD-SCDMA,, receive signal based on TD-SCDMA or GSM to realize emission by opening switch (43 or 44) with duplexer (41) and GSM duplexer (42).

As the above-mentioned detailed description of doing, the present invention constitutes a circuit to TD_SCDMA with switch (duplexer), GSM with duplexer and the required switch of On/Off emission RX path, thereby the isolation and the receiving terminal noise factor (NF) of GSM pattern and TD-SCDMA pattern have been improved, not only can improve the entire system performance, but also have the effect that reduces the duplexer size.

Claims (3)

1. the double-mode duplexer of a mobile communication terminal is characterized in that having as lower device, can improve receptivity:

The 1st signal separator is in order to separate the transmitting and receiving signal based on TD-SCDMA;

The 2nd signal separator is in order to separate the transmitting and receiving signal based on GSM;

The 1st jockey is in order to be connected to antenna above-mentioned the 1st signal separator;

The 2nd jockey is in order to be connected to antenna above-mentioned the 2nd signal separator.

2. the double-mode duplexer of mobile communication terminal according to claim 1 is characterized in that the 1st signal separator is made of switch or duplexer.

3. the double-mode duplexer of mobile communication terminal according to claim 1 is characterized in that the 2nd signal separator is made of duplexer.

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