Control method for reducing spurious signals of transmitter and transmitter

Abstract

The invention discloses a control method for reducing spurious signals of a transmitter and the transmitter, and the control method comprises the steps: enabling a phase-locked loop power supply circuit and a baseband module power supply circuit to output power supply voltage through a transmitter control center, and completing the power-on of a phase-locked loop and a baseband signal processing module of the transmitter; a digital gain unit is initialized to be in a lowest gain working state, and a pre-power amplifier is initialized to be in a lowest gain working state; setting a target local frequency through frequency control until the frequency of the phase-locked loop is locked; the transmitter control center enables the radio frequency circuit module to output power supply voltage to complete power-on of the radio frequency circuit module; and according to a preset gain control function, circuit gains of the digital gain unit and the pre-power amplifier are gradually improved through baseband gain control and radio frequency gain control until the output power of the transmitter reaches a preset output power target, and the transmitter enters a normal working state. According to the invention, the generation of spurious signals is effectively suppressed by optimizing the starting sequence and the gain control strategy of the transmitter.

Description

Technical Field

[0001] The present invention relates to the field of transmitters, and in particular to a control method for reducing transmitter spurious signals and a transmitter. Background Art

[0002] As a key component of wireless communication systems, RF transmitters are responsible for up-converting baseband signals and amplifying them to sufficient power before transmitting them through antennas. In practical applications, transmitters must be frequently turned on and off as needed to save power or prevent the negative impact of long-term transmission on devices and users. However, when these signals are turned off and on again, transient spurious signals are often generated. This not only interferes with normal communications in other frequency bands but can also degrade the transmitter's own performance and even violate electromagnetic compatibility standards, posing a serious threat to the reliability and stability of the entire communication system.

[0003] The reasons are as follows: 1. After the transmitter is turned on, the local oscillator frequency takes a certain amount of time to stabilize. If the transmit output circuit is turned on synchronously at this time, the unstable local oscillator frequency will be transmitted to the RF output end through the mixing, which will manifest as frequency drift spurious. 2. If the transmitter gain suddenly changes from low to high at the moment of turning on, it will cause the transmit output power to change sharply. This sudden change will also cause the generation of spurious signals. Summary of the Invention

[0004] In order to overcome the above technical defects, the present invention provides a control method for reducing transmitter spurious signals and a transmitter, which can reduce instantaneous spurious signals during the transmitter startup process.

[0005] In order to solve the above problems, the present invention is implemented according to the following technical solutions: A control method for reducing transmitter spurious signals comprises the steps of: The transmitter control center controls the power supply so that the phase-locked loop power supply circuit and the baseband module power supply circuit of the power management unit output the power supply voltage, thereby powering on the phase-locked loop and baseband signal processing module of the transmitter. The transmitter control center initializes the digital gain unit to the lowest gain working state through baseband gain control, and initializes the pre-power amplifier to the lowest gain working state through baseband gain control; The transmitter control center sets the target local oscillator frequency through frequency control and waits until the frequency of the phase-locked loop is locked; The transmitter control center controls the power supply so that the RF circuit module of the power management unit outputs the power supply voltage, completing the power-on of the RF circuit module. The transmitter control center gradually increases the circuit gain of the digital gain unit and pre-power amplifier through baseband gain control and RF gain control according to the preset gain control function until the transmitter output power reaches the preset output power target and enters normal working state.

[0006] As a further improvement of the present invention, the steps of setting the target local oscillator frequency and waiting until the frequency of the phase-locked loop is locked are repeated until the locking indication flag of the phase-locked loop is 1.

[0007] As a further improvement of the present invention, the preset gain control function includes: a linear interpolation function and an exponential function.

[0008] The present invention also provides a transmitter for implementing the above control method, comprising: a baseband signal processing module, a radio frequency circuit module, a power management unit, a transmitter control center, and a phase-locked loop; The input end of the baseband signal processing module is connected to the baseband input signal, the output end is connected to the input end of the radio frequency circuit module, and the output end of the radio frequency circuit module outputs the radio frequency signal; The transmitter control center is connected to the baseband signal processing module, the radio frequency circuit module, and the phase-locked loop; The transmitter control center is connected to the baseband signal processing module, the radio frequency circuit module, and the phase-locked loop through the power management unit; The transmitter control center is connected to the radio frequency circuit module through the power management unit and the phase-locked loop; The transmitter control center is connected to the radio frequency circuit module through the phase-locked loop.

[0009] As a further improvement of the present invention, the power management unit includes: a baseband module power supply circuit, a radio frequency module power supply circuit and a phase-locked loop power supply circuit; The transmitter control center is connected to the baseband signal processing module through the baseband module power supply circuit; The transmitter control center is connected to the radio frequency circuit module through the radio frequency module power supply circuit; The transmitter control center is connected to the phase-locked loop through the phase-locked loop power supply circuit.

[0010] As a further improvement of the present invention, the baseband signal processing module includes: an interpolation filter, a digital gain unit, a digital-to-analog converter, and an analog filter connected in sequence; The input end of the interpolation filter is connected to the baseband input signal; The transmitter control center is connected to the digital gain unit, and the output end of the analog filter is connected to the radio frequency circuit module.

[0011] As a further improvement of the present invention, the radio frequency circuit module includes: an up-converter and a pre-power amplifier connected in sequence; The up-converter is connected to the phase-locked loop; The input end of the up-converter is connected to the output end of the analog filter, and the output end of the pre-power amplifier outputs the radio frequency signal.

[0012] Compared with existing technologies, this invention offers the following advantages: By optimizing the transmitter startup sequence, frequency drift spurious signals generated during the frequency calibration process after the phase-locked loop is powered on are prevented from being amplified by the transmitter and output outside the chip. By gradually controlling the transmitter gain, spurious signals caused by sudden changes in transmitter output power are avoided. Through orderly control by the transmission control center, the power of transmitted spurious signals is reduced, the frequency purity of the transmitter output signal is improved, and the reliability of the communication system in complex electromagnetic environments is enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a flow chart of the control method of the present invention; Figure 2 This is a schematic diagram of the power management unit according to the present invention; Figure 3 It is a structural diagram of the transmitter of the present invention. DETAILED DESCRIPTION

[0014] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0015] The present invention provides a control method for reducing transmitter spurious signals, such as Figure 1 As shown, the steps include: S1, the transmitter control center controls the power supply to make the phase-locked loop power supply circuit and baseband module power supply circuit of the power management unit output the power supply voltage, completing the power-on of the transmitter's phase-locked loop and baseband signal processing module. Figure 2 As shown, turn on the LDO_PLL of the power management unit, connect the switch SW6, make VDD_PLL reach the normal working supply voltage required by the phase-locked loop, and complete the power-on of the phase-locked loop; turn on the LDO_DIG of the power management unit, connect the switch SW3, make VDD_DIG reach the normal working supply voltage required by the interpolation filter and the digital gain unit, and complete the power-on of the interpolation filter and the digital gain unit; turn on the LDO_DAC of the power management unit, connect the switch SW2, make VDD_DAC reach the normal working supply voltage required by the digital-to-analog converter, and complete the power-on of the digital-to-analog converter; turn on the LDO_LPF of the power management unit, connect the switch SW1, make VDD_LPF reach the normal working supply voltage required by the analog filter, and complete the power-on of the analog filter.

[0016] S2. The transmitter control center initializes the digital gain unit to its lowest gain state through baseband gain control. Also, the baseband gain control initializes the pre-power amplifier to its lowest gain state. Assuming the digital gain unit's gain range is -31dB to 0dB, the baseband gain control sets the initial gain of the digital gain unit to -31dB. Assuming the pre-power amplifier's gain range is 0dB to 12dB, the initial gain is set to 0dB.

[0017] S3. The transmitter control center sets the target local oscillator frequency through frequency control and waits until the frequency of the phase-locked loop is locked; when the lock indication mark of the phase-locked loop is Lock=0, it is in a waiting state, and when the lock indication mark is Lock=1, it enters step S4.

[0018] S4, the transmitter control center controls the power supply to make the RF circuit module of the power management unit output the power supply voltage, thus completing the power-on of the RF circuit module. Figure 2 As shown, turn on LDO_MIX of the power management unit, connect switch SW5, make VDD_MIX reach the normal working supply voltage required by the up-converter, and complete the power-on of the up-converter; turn on LDO_PPA of the power management unit, connect switch SW4, make VDD_PPA reach the normal working supply voltage required by the pre-power amplifier, and complete the power-on of the pre-power amplifier.

[0019] S5. The transmitter control center gradually increases the circuit gain of the digital gain unit and pre-power amplifier according to the preset gain control function until the output power reaches the preset output power target and the transmitter enters normal operation. For example, if the gain increases from -31dB to 0dB, the gain change rate is controlled, not directly from -31dB to 0dB. For example, a linear interpolation function or exponential function is used to gradually increase the gain from -31dB to 0dB.

[0020] The preset gain control function is set to make the gain change regular, avoid sudden changes in the transmit output power, and reduce spurious signals caused by transient gain changes. The preset gain control function includes: linear function, exponential function or other smoothly increasing mathematical function forms.

[0021] By stabilizing the local oscillator frequency before activating the transmit output circuit and employing a gradual gain control method, the present invention effectively avoids the generation of spurious signals caused by frequency instability and power fluctuations. This significantly reduces the spurious level at the moment the transmitter is activated, improves the purity of the transmitted signal, and enhances the reliability and stability of the entire communication system. This is particularly advantageous in complex communication environments where spectrum resources are scarce and multiple frequency bands coexist. By rationally and effectively controlling the transmit frequency and power output, the transmitter can enter a stable operating state more quickly, shortening the transmitter's warm-up time and reducing the transmitter's inactive operating time, thereby lowering the average power consumption of the transmitter in actual applications.

[0022] The present invention provides a transmitter, such as Figure 3 As shown, the control method used to implement the above-mentioned method includes: a baseband signal processing module, a radio frequency circuit module, a power management unit, a transmitter control center, and a phase-locked loop; the input end of the baseband signal processing module is connected to the baseband input signal, the output end is connected to the input end of the radio frequency circuit module, and the output end of the radio frequency circuit module outputs the radio frequency signal; the transmitter control center is connected to the baseband signal processing module and the radio frequency circuit module; the transmitter control center is connected to the baseband signal processing module and the radio frequency circuit module through the power management unit; the transmitter control center is connected to the radio frequency circuit module through the power management unit and the phase-locked loop; the transmitter control center is connected to the radio frequency circuit module through the phase-locked loop.

[0023] A phase-locked loop (PLL) circuit generates the target local oscillator frequency (flo) based on the reference clock frequency and the division ratio. After the PLL is powered on, the output frequency is in the unlocked state (Lock = 0), generating a signal that differs from the target local oscillator frequency (flo). If the transmitter is fully powered on at this time, this can cause unexpected spurious signals in the transmit output. After the PLL operates for a period of time, the output local oscillator frequency will lock to the target local oscillator frequency (flo), and the PLL lock indicator (Lock = 1) will be displayed.

[0024] Furthermore, the power management unit includes: a baseband module power supply circuit, a radio frequency module power supply circuit, and a phase-locked loop power supply circuit; the transmitter control center is connected to the baseband signal processing module via the baseband module power supply circuit; the transmitter control center is connected to the radio frequency circuit module via the radio frequency module power supply circuit; and the transmitter control center is connected to the phase-locked loop via the phase-locked loop power supply circuit. The baseband module power supply circuit powers the interpolation filter, digital gain unit, digital-to-analog converter, and analog filter; the radio frequency module power supply circuit powers the upconverter and pre-power amplifier; and the phase-locked loop power supply circuit powers the phase-locked loop. The power supply circuits are controlled by the transmitter control center and can be powered on or off independently.

[0025] Furthermore, the baseband signal processing module includes a sequentially connected interpolation filter, a digital gain unit, a digital-to-analog converter, and an analog filter. The input of the interpolation filter is connected to the baseband input signal. The transmitter control center is connected to the digital gain unit, and the output of the analog filter is connected to the RF circuit module. The baseband signal processing module is used to perform interpolation filtering, digital gain control, digital-to-analog conversion, and analog filtering on the baseband input signal fbb, converting the input digital baseband signal into an analog baseband signal with a high signal-to-noise ratio and controllable amplitude.

[0026] The RF circuit module includes an upconverter and a pre-power amplifier connected in sequence. The upconverter is connected to a phase-locked loop (PLL). The upconverter input is connected to the output of the analog filter, and the pre-power amplifier outputs the RF signal. The RF circuit module is used to upconvert the analog baseband signal and amplify the RF signal, converting it into an RF signal (FRF) with a specific transmit output frequency and power.

[0027] The transmitter control center is used to control the baseband signal processing module, RF circuit module, and phase-locked loop on and off according to the timing of the invention steps, and generates the transmitter's local oscillator signal flo through the phase-locked loop. By presetting a reasonable control process and timing, the local oscillator frequency is ensured to be stable before the control signal path of the transmission output circuit is turned on. Secondly, the transmitter digital gain unit and pre-power amplifier gain are controlled through baseband gain control and RF gain control. According to a preset gain gradient function, the gain is gradually increased from an initial small gain to a target gain value. This function can take the form of a linear function, an exponential function, or other smoothly increasing mathematical function to ensure that the gain changes smoothly and avoid sudden changes.

[0028] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A control method for reducing transmitter spurious signals, characterized in that: Including steps: The transmitter control center controls the power supply so that the phase-locked loop power supply circuit and the baseband module power supply circuit of the power management unit output the power supply voltage, thereby powering on the phase-locked loop and baseband signal processing module of the transmitter. The transmitter control center initializes the digital gain unit to the lowest gain working state through baseband gain control, and initializes the pre-power amplifier to the lowest gain working state through baseband gain control; The transmitter control center sets the target local oscillator frequency through frequency control and waits until the frequency of the phase-locked loop is locked; The transmitter control center controls the power supply so that the RF circuit module of the power management unit outputs the power supply voltage, completing the power-on of the RF circuit module; The transmitter control center gradually increases the circuit gain of the digital gain unit and pre-power amplifier through baseband gain control and RF gain control according to the preset gain control function until the transmitter output power reaches the preset output power target and enters normal working state.

2. The control method according to claim 1, characterized in that: Repeat the steps of setting the target local oscillator frequency and waiting until the frequency of the phase-locked loop is locked, until the lock indication flag of the phase-locked loop is 1.

3. The control method according to claim 1, wherein: The preset gain control function includes: a linear interpolation function and an exponential function.

4. A transmitter, characterized in that: Used to implement the control method according to any one of claims 1 to 3, comprising: a baseband signal processing module, a radio frequency circuit module, a power management unit, a transmitter control center, and a phase-locked loop; The input end of the baseband signal processing module is connected to the baseband input signal, the output end is connected to the input end of the radio frequency circuit module, and the output end of the radio frequency circuit module outputs the radio frequency signal; The transmitter control center is connected to the baseband signal processing module, the radio frequency circuit module, and the phase-locked loop; The transmitter control center is connected to the baseband signal processing module, the radio frequency circuit module, and the phase-locked loop through the power management unit; The transmitter control center is connected to the radio frequency circuit module through the power management unit and the phase-locked loop; The transmitter control center is connected to the radio frequency circuit module through the phase-locked loop.

5. The transmitter according to claim 4, characterized in that The power management unit includes: a baseband module power supply circuit, a radio frequency module power supply circuit and a phase-locked loop power supply circuit; The transmitter control center is connected to the baseband signal processing module through the baseband module power supply circuit; The transmitter control center is connected to the radio frequency circuit module through the radio frequency module power supply circuit; The transmitter control center is connected to the phase-locked loop through the phase-locked loop power supply circuit.

6. The transmitter according to claim 5, characterized in that The baseband signal processing module includes: an interpolation filter, a digital gain unit, a digital-to-analog converter, and an analog filter connected in sequence; The input end of the interpolation filter is connected to the baseband input signal; The transmitter control center is connected to the digital gain unit, and the output end of the analog filter is connected to the radio frequency circuit module.

7. The transmitter according to claim 6, characterized in that The radio frequency circuit module includes: an up-converter and a pre-power amplifier connected in sequence; The up-converter is connected to the phase-locked loop; The input end of the up-converter is connected to the output end of the analog filter, and the output end of the pre-power amplifier outputs the radio frequency signal.

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