WO2016026301A1

WO2016026301A1 - Signal input device, global positioning system (gps) frequency adjuster, and terminal

Info

Publication number: WO2016026301A1
Application number: PCT/CN2015/075728
Authority: WO
Inventors: 罗迤宝
Original assignee: 中兴通讯股份有限公司
Priority date: 2014-08-20
Filing date: 2015-04-01
Publication date: 2016-02-25

Abstract

The present utility model provides a signal input device, a global positioning system (GPS) frequency adjuster, and a terminal. The signal input device comprises a pulse density modulation (PDM) wave output port, and a PDM wave receiving port for receiving a PDM wave. A first phase-shift RC circuit is connected to the PDM wave output port and the PDM wave receiving port, and a buffer is connected between the PDM wave output port and the first RC circuit. By means of the present utility model, a problem in the related art that the fluctuation of the amplitude of a PDM wave cannot be effectively inhibited is solved, thereby achieving an effect of buffering the fluctuation of the amplitude of the PDM wave.

Description

Signal input device, global positioning system GPS frequency adjuster and terminal

Technical field

The utility model relates to the field of communication, in particular to a signal input device, a global positioning system GPS frequency adjuster and a terminal.

Background technique

The Global Position System (GPS) function has become the standard configuration of intelligent terminals, which is convenient and easy to use, and can bring great convenience to users without relying on the characteristics of the terminal network. Currently, the application of intelligent terminals GPS functions are also widely used in software. Accurate and reliable GPS performance will bring a very good user experience to the smartphone.

However, in the actual use of GPS, there are often some difficulties encountered. Taking the smart phone as an example, the accuracy of the frequency of the GPS module is very high. In the current smart phone platform, the common GPS design clock is often It is the crystal sharing of the wireless transceiver unit of the mobile phone. The use of wireless networks, the fever of smartphones, and the coexistence of other modules inside the phone pose significant challenges to GPS performance.

From the current common GPS faults: the first slow search speed, difficult satellite analysis, frequent star-loss in dual-mode networks, etc., the cause of the fault is concentrated in the environmental or electromagnetic compatibility of the GPS crystal oscillator (ElectroMagnetic Compatibility, referred to as EMC) The impact of these unfavorable factors greatly hinders the experience of GPS users.

Although the current mobile smart platform and motherboard design have made a lot of efforts to solve this problem, the wireless module crystal oscillator sharing, the use of smart phones and other issues will still have a great impact on the GPS module.

1 is a TCXO adjustment circuit in the related art. As shown in FIG. 1 , in a GPS Temperature Compensated Crystal Oscillator (TCXO) circuit, a VTC pin of a TCXO is applied by an application processor AP main chip. Control, the pulse frequency intensity modulation (PDM) wave control TCXO initial frequency fine-tuning, TCXO output to the power management chip (Power Management referred to as PM), all the way to the RF wireless module, usually the GPS module is integrated In the RF wireless module, the respective frequencies are generated by respective up-conversion circuits. The frequency tuning of TCXO is adjusted by PDM. TCXO has its own temperature compensation circuit, which can adjust the frequency fluctuation caused by temperature change. However, GPS requires high frequency accuracy of the clock. We often find it in the analysis of mobile phones with GPS faults. There are high harmonics and pulse clutter on the control signal of PDM. These interferences will cause the crystal output frequency to fluctuate by 1-2HZ. Although this fluctuation is small relative to the crystal frequency output, but for GPS, which is sensitive to frequency requirements, this kind of tiny jitter has a great influence on the first positioning of GPS. The visible phenomenon is GPS. Sufficient satellites have been received, and the signal-to-noise ratio is relatively good, but the location information cannot be resolved. If this kind of jitter persists, it will cause the GPS of the mobile phone to be unable to complete positioning. This kind of pulse wave is generally generated when the frequency change of the wireless network of the mobile phone wireless module is changed. This adjustment is especially frequent in the dual mode operation mode, so the GPS performance may be seriously deteriorated at this time. In addition, the PDM waveform generated by the main chip is generally a rectangular square wave, so the high harmonic components are rich, which also affects the frequency adjustment of the TCXO.

Therefore, there is a problem in the related art that the fluctuation of the PDM wave in amplitude cannot be effectively suppressed.

Utility model content

The utility model provides a signal input device, a global positioning system GPS frequency adjuster and a terminal, so as to at least solve the problem that the related art cannot effectively suppress the fluctuation of the PDM wave in amplitude.

According to an aspect of the present invention, a signal input device is provided, comprising: a pulse intensity modulated PDM wave output port, a PDM wave receiving port receiving the PDM wave, and the PDM wave output port and the PDM wave receiving The port is connected to a first phase shift RC circuit, and a buffer is connected between the PDM wave output port and the first RC circuit.

In an embodiment of the invention, the buffer frequency of the buffer is adapted to the frequency of the PDM wave.

In an embodiment of the present invention, the buffer frequency of the buffer is adapted to the frequency of the PDM wave, and the frequency of the buffer is the same as the frequency of the PDM wave.

In an embodiment of the present invention, the buffer includes an enable pin for preventing amplification of a wave signal of the PDM wave, and the enable pin is grounded.

In an embodiment of the invention, one or more second RC circuits are connected between the output pin of the buffer and the first RC circuit.

In an embodiment of the invention, the resistance value and the capacitance value of the one or more second RC circuits are determined by the frequency of the PDM wave output by the buffer.

According to another aspect of the present invention, a global positioning system GPS frequency adjuster is provided, comprising the signal input device and the temperature compensated crystal oscillator TCXO according to any of the above.

In an embodiment of the present invention, the input pin Vcont of the TCXO is a PDM wave receiving port of the signal input device.

According to still another aspect of the present invention, a terminal is provided, comprising the GPS frequency adjuster of any of the above.

The utility model provides a signal output device with a buffer connected between a PDM wave output port and a first phase shift RC circuit, which solves the problem that the fluctuation of amplitude of the PDM wave cannot be effectively suppressed in the related art. Further, the effect of buffering the fluctuation of the PDM wave in amplitude is achieved.

DRAWINGS

The drawings are intended to provide a further understanding of the present invention, and are intended to be a part of the present invention, and the description of the present invention is intended to be illustrative of the invention and is not intended to limit the invention. In the drawing:

1 is a TCXO adjustment circuit in the related art;

2 is a block diagram showing the structure of a signal input device according to an embodiment of the present invention;

3 is a block diagram showing a preferred structure of a signal input device according to an embodiment of the present invention;

4 is a global positioning system GPS frequency adjuster in accordance with an embodiment of the present invention;

FIG. 5 is a structural block diagram of a terminal according to an embodiment of the present invention; FIG.

6 is a GPS frequency adjustment circuit in accordance with an embodiment of the present invention.

detailed description

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings in conjunction with the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict.

2 is a structural block diagram of a signal input device according to an embodiment of the present invention. As shown in FIG. 2, the signal input device includes: a pulse intensity modulated PDM wave output port 22, and a PDM wave receiving port 24 that receives the PDM wave. The PDM wave output port is connected to the PDM wave receiving port with a first phase shift RC circuit 26, and a buffer 28 is connected between the PDM wave output port and the first RC circuit. In the device, the buffer 28 can correctly transmit the duty cycle variation of the PDM wave, and can effectively isolate the amplitude of the PDM wave, thereby isolating the interference caused by the PDM fluctuation.

In a preferred embodiment, the buffer frequency of the buffer can be adapted to the frequency of the PDM wave to effectively isolate the amplitude of the PDM wave.

Wherein, in the above preferred embodiment, when the buffer device is selected, a device having the same buffer frequency as the frequency of the PDM wave can be selected, so that the higher harmonics in the PDM wave can be effectively suppressed and isolated, and the PDM wave can be prevented. Abnormal jitter.

In a preferred embodiment, an enable pin for preventing the PDM wave from being amplified may also be provided in the buffer, and the enable pin may be grounded. This allows the buffer device to function as isolation and shaping without the enhanced drive capability of the buffer device.

3 is a block diagram showing a preferred structure of a signal input device according to an embodiment of the present invention. As shown in FIG. 3, the device includes one or more second RC circuits 32 in addition to the device shown in FIG.

As can be seen from FIG. 3, one or more second RC circuits may be connected between the output pin of the buffer and the first RC circuit, and the second RC circuit may be a frequency selective low pass circuit, thereby increasing the high order of the PDM wave. Harmonic suppression effect. Of course, the second RC circuit may not be added, and the first RC circuit may be appropriately adjusted to achieve the effect of suppressing higher harmonics in the PDM wave.

In the preferred embodiment described above, the resistance and capacitance values of one or more of the RC circuits can be determined by the frequency of the PDM wave output by the buffer to enhance the suppression of higher harmonics.

4 is a global positioning system GPS frequency adjuster according to an embodiment of the present invention. As shown in FIG. 4, the GPS frequency adjuster 40 includes the signal input device 42 and the temperature compensated crystal oscillator TCXO 44 of any of the above. It can be seen from the above that the signal input device can effectively suppress the jump of the amplitude of the PDM wave and shape the PDM wave. Therefore, the GPS frequency adjuster composed of the signal input device 42 and the temperature compensated crystal oscillator TCXO44 can effectively achieve stability. The purpose of the GPS crystal frequency.

Further, when a specific line connection is made, the input pin Vcont of the TCXO can be set as the PDM wave receiving port of the signal input device. Thereby achieving the above purpose of stabilizing the GPS crystal frequency.

FIG. 5 is a structural block diagram of a terminal according to an embodiment of the present invention. As shown in FIG. 5, the terminal 50 includes the GPS frequency adjuster 52 of any of the above.

The utility model will be described below by taking a mobile phone as an example.

In the related art, the following problems exist. In the current smart phone solutions provided by various chip manufacturers, it is common for the entire system to share a master clock, and different RF transceiver chips share the master clock to achieve Their respective functions, but when these RF transceiver modules work at the same time, the master clock will make minor adjustments according to the working state of each module, such as wireless wifi, BitTorrent (BT), Global Mobile Communications ( Global system for Mobile Communication (referred to as GSM), Code Division Multiple Access (CDMA), etc. The fine-tuning of the clock during communication has little effect on its performance, but when the GPS module is shared with these RF modules. At the time, the fine-tuning of the clock will have a very fatal effect on the positioning of the GPS, which will result in a long initial positioning time, poor positioning accuracy, and frequent star-dropping situations, which will bring great experience to users using GPS. Obstacles.

In this regard, the present invention provides the following technical solution: a buffer circuit is added to the clock circuit of the mobile phone, so that the frequency change of the mutation can be buffered, and a buffer circuit with a processing speed matching the clock frequency can be selected, and the rate can be removed. The interference of the higher harmonic components of the clock, so that the PDM wave used to control the clock shaping will be cleaner, thus achieving the effect of stabilizing the clock.

It can be seen from the circuit shown in Fig. that the adjustment of the clock is adjusted by the PDM wave, which is issued by the chip, and the duty ratio of the PDM is changed according to the temperature change to adjust the stable clock frequency when interference occurs. The amplitude of the PDM will jump, which causes the pulse width voltage to change, causing a change in the clock frequency.

6 is a GPS frequency adjustment circuit according to an embodiment of the present invention. As shown in FIG. 6, the frequency adjustment circuit adds a buffer circuit based on FIG. 1, and the buffer circuit can correctly transmit the duty of the PDM wave. The ratio changes, and the amplitude of the PDM wave is isolated by the buffer, thereby isolating the interference.

Wherein, as shown in FIG. 6, a buffer circuit is added to the PDM signal path, and the main purpose of the buffer circuit is to eliminate the instantaneous jitter of the PDM and the shaping of the PDM waveform, and select the response frequency and the PDM wave when selecting the buffer device. For a frequency-similar circuit, it is preferable to select a buffer having the same response frequency and the frequency of the PDM wave, so as to ensure strong suppression and isolation of the higher harmonics, and selecting a suitable device for the time can be abnormal. The jitter is isolated so that the stable TCXO circuit guarantees the performance of the GPS.

Moreover, the RC frequency-selective low-pass circuit (the second RC circuit described above) is used on the snubber circuit output railway to increase the effect of suppressing the higher harmonics, and the specific resistance value and capacitance value of the RC circuit are determined by the PDM wave. Frequency is determined. The RC circuit and the selection of a suitable frequency response buffer device can guarantee the suppression of higher harmonics.

The usual buffer device also has an enhanced driving effect on the waveform. In order to prevent the PDM wave signal from being amplified in the smartphone, the enable pin of the buffer can be grounded, so that the enhanced driving capability of the buffer device can be eliminated. Therefore, the function of the buffer device is only the function of isolation and shaping, and the peripheral circuit of the buffer is used to achieve the purpose of stabilizing the GPS crystal frequency.

Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device, which can be concentrated on a single computing device or distributed among multiple computing devices. On the network, optionally, they may be implemented by program code executable by the computing device such that they may be stored in the storage device by the computing device and, in some cases, may be different from The steps shown or described are performed sequentially, or they are separately fabricated into individual integrated circuit modules, or a plurality of modules or steps thereof are fabricated into a single integrated circuit module. Thus, the invention is not limited to any specific combination of hardware and software.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention. For those skilled in the art, various modifications and changes can be made in the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Industrial applicability

As described above, with the above-described embodiments and preferred embodiments, the problem of the inability to effectively suppress the fluctuation of the amplitude of the PDM wave in the related art is solved, and the effect of buffering the fluctuation of the PDM wave in amplitude is achieved.

Claims

A signal input device includes: a pulse intensity modulated PDM wave output port, a PDM wave receiving port receiving the PDM wave, and a first phase shift RC circuit connected to the PDM wave receiving port and the PDM wave receiving port, A buffer is connected between the PDM wave output port and the first RC circuit.
The apparatus of claim 1 wherein the buffer frequency of the buffer is adapted to the frequency of the PDM wave.
The apparatus of claim 2, wherein the buffer frequency of the buffer is adapted to the frequency of the PDM wave comprises:

The buffer has a buffer frequency that is the same as the frequency of the PDM wave.
The apparatus of claim 1, wherein the buffer comprises an enable pin for preventing amplification of a wave signal of the PDM wave, the enable pin being grounded.
The apparatus of claim 1 wherein one or more second RC circuits are coupled between the output pin of the buffer and the first RC circuit.
The apparatus of claim 4 wherein the resistance and capacitance values of said one or more second RC circuits are determined by the frequency of said PDM waves output by said buffer.
A global positioning system GPS frequency adjuster comprising the signal input device of any of claims 1-6 and a temperature compensated crystal oscillator TCXO.
The GPS frequency adjuster according to claim 7, wherein the input pin Vcont of the TCXO is a PDM wave receiving port of the signal input device.
A terminal comprising the GPS frequency adjuster of any one of claims 7 to 8.