TWI819726B - A radio frequency transmitter and a calibrating method of radio frequency output power therefor - Google Patents

Abstract

A radio frequency (RF) transmitter and a calibrating method of RF output power therefor are provided. The RF transmitter includes a processing circuit, a transmitting element and a power detecting element. The processing circuit adjusts a power gain index of the emitting element to sequentially make the emitting element emit RF signal with a first power and a second power. The processing circuit, according to a linear equation, correspondingly obtains a first power index and a second power index. The processing circuit obtains a calibrated slope in accordance with the first power, the second power, the first power index and the second power index. The processing circuit replaces the default slope of the linear equation with the calibrated slope.

Description

Radio frequency transmitter and radio frequency output power correction method

The present invention corrects radio frequency output, and in particular relates to a radio frequency transmitter and a radio frequency output power correction method thereof.

Radio frequency transmitters have increasingly higher requirements for the accuracy of signal output power. In the past, open loop power control was mainly used to achieve precise control by adjusting the gain index of the radio frequency transmitter. However, open loop power control lacks a feedback control mechanism, resulting in the accuracy of this method. Gradually it cannot meet the demand. Since Closed Loop Power Control has a feedback control mechanism, which further improves the overall accuracy, the closed loop power control method has been gradually introduced into the industry.

During the design and development stage of the radio frequency transmitter, the internal power detection circuit parameters (bias voltage, attenuation circuit) of the transmitting unit will be adjusted to achieve a slope of the linear relationship between the intensity index value and the signal output power in line with the design. However, due to the offset of the analog circuit, the Different from the layout, the slope of the linear relationship between the signal output power of the transmitting unit and the intensity index value can easily cause the linear relationship between the two to be less than expected when the IC is mass-produced, and must be corrected before leaving the factory.

One embodiment of the present invention provides a radio frequency transmitter, which includes a transmitting element, a detecting element and a processing circuit. The transmitting element is used to send out a radio frequency signal according to a gain level and an input signal; the detecting element is used to detect and Obtain the signal power of the radio frequency signal; the processing circuit has a linear relational expression, and the linear relational expression has a preset slope value. The processing circuit is used to: adjust the gain gear so that the radiofrequency signal emitted by the transmitting element is The signal power conforms to a first power, and a first intensity index value is obtained according to the linear relationship; the gain level is adjusted so that the signal power of the radio frequency signal emitted by the transmitting element conforms to a second power, and according to The linear relationship formula obtains a second intensity index value; obtains a slope correction value according to the first power, the second power, the first intensity index value and the second intensity index value; and replaces the slope correction value with the Slope default value.

One embodiment of the present case provides a radio frequency output power correction method, suitable for a radio frequency transmitter. The radio frequency transmitter has a linear relationship expression, and the linear relationship expression has a slope preset value. The correction method includes: adjusting the radio frequency transmitter. A gain level of a transmitting element to sequentially make the two radio frequency signals emitted by the transmitting element comply with a first power and a second power; according to the linear relationship, a corresponding first intensity index value and a corresponding a second intensity index value; obtain a slope correction value based on the first power, the second power, the first intensity index value and the second intensity index value; and replace the slope default value with the slope correction value.

Based on the above, some embodiments of the present invention provide a radio frequency transmitter and a radio frequency output power correction method. The slope correction value is obtained by using the power difference and the intensity index difference to correct the slope in the linear relationship, so that the radio frequency transmitter The relationship between the power emitted during operation and the intensity indicator can be in line with expectations. In this way, every RF transmitter product after mass production can be calibrated in this way, so that the accuracy of the output power can be optimized. And improve the overall yield of the production line.

10: Emitting element

11:Transmitter

12:Power amplifier

20:Detection component

21: Power detection circuit

22:Analog to digital conversion circuit

30: Processing circuit

31:Digital circuit

32: Comparison circuit

L1: dashed line

L2: solid line

L3: dashed line

L4: solid line

A: Gain gear

B:Input signal

C: Vector signal analyzer

FIG. 1 is a functional block diagram according to some embodiments of the present invention.

FIG. 2 is a flow chart of a radio frequency output power correction method according to some embodiments of the present invention.

FIG. 3 is a schematic diagram illustrating the ideal relationship and the actual relationship between intensity index and output power according to some embodiments of the present invention.

FIG. 4 is a schematic diagram illustrating the ideal relationship between intensity index and output power and the actual relationship after slope correction according to some embodiments of the present invention.

Please refer to FIG. 1 . In some embodiments, the radio frequency transmitter includes: a transmitting element 10 , a detecting element 20 , and a processing circuit 30 . The operation modes and embodiments of each element are introduced below.

As shown in FIG. 1 , the transmitting element 10 includes a transmitter 11 and a power amplifier 12 . The transmitting element 10 emits a radio frequency signal according to a gain level A and an input signal B.

The detection element 20 is used to detect and obtain the signal power of the radio frequency signal. In some embodiments, the detection element 20 includes a power detection circuit 21 and an analog-to-digital conversion circuit 22. The power detection circuit 21 is used to detect The radio frequency signal obtains a power analog value, and the analog-to-digital conversion circuit 22 converts the power analog value into the signal power.

The processing circuit 30 has a linear relationship y = ax + b , which represents the relationship between the intensity index and the output power when the radio frequency transmitter is activated. The ideal linear relationship is y = a _ref x + b _ref , Among them, y represents the intensity index value, x represents the output power value, and a _ref represents the preset value of the slope of the preset value. Please refer to Figure 3. The dotted line L1 represents the ideal linear relationship when the RF transmitter operates. However, in fact, the RF transmitter will be affected by the manufacturing process or circuit layout, resulting in the actual linear relationship as shown in Figure 3. As shown in L2, the actual linear relationship equation is y = a ₀ x + b ₀ , where a ₀ represents the actual value of the slope, so the processing circuit 30 will perform a correction process for the linear relationship equation.

Please refer to Figure 1 together with Figure 3. The correction process of the processing circuit 30 is to adjust the gain level A of the transmitting element 10 so that the signal power of the radio frequency signal emitted by the transmitting element 10 meets a first power value x ₁ . The circuit 30 obtains a first intensity index value y ₁ corresponding to the first power value according to the linear relational expression; then the processing circuit 30 adjusts the gain gear A of the transmitting element 10 so that the signal power of the radio frequency signal meets a second Power x ₂ , the processing circuit 30 obtains a second intensity index value y ₂ corresponding to the second power value based on the linear relationship; then the processing circuit 30 obtains a power difference value based on the first power x ₁ and the second power x ₂ △x, and then obtain a strength index difference value △y based on the first strength index value y ₁ and the second strength index value y ₂ . In some embodiments, the processing circuit 30 includes a digital circuit 31. The digital circuit 31 is used to obtain a corresponding strength index value (transmit signal strength indicator codeword, TSSI codeword) based on the signal power and the linear relationship. In one embodiment, the signal power is in the form of voltage. In one embodiment, the digital circuit 31 is a TSSI digital circuit, which can convert a digital signal representing signal strength into a corresponding TSSI value.

得到公式(2)如下：

其中公式(2)可以改寫為公式(3)如下：

由圖3實線L2可知斜率實際值a ₀為：

故公式(3)又可以改寫為：

其中

為斜率校正值

。也因此，處理電路30用以根據功率差值、強度指標差值、修正參數、斜率預設值以及斜率修正函數得到斜率校正值

。並將斜率校正值取代該斜率預設值，則得到斜率校正後之線性關係式：

。 Next, the processing circuit 30 calculates the slope correction value according to the power difference value Δx and the intensity index difference value Δy. The calculation method is that the processing circuit 30 has a slope correction function and a correction parameter a, and the slope correction function and the correction parameter a can correspond to the actual value of the slope a ₀ , and its formula (1) is as follows: f ( a ) = a ₀ . In order to make the actual slope value a ₀ satisfy the slope preset value a _ref , formula (1) can be multiplied by

The formula (2) is obtained as follows:

Formula (2) can be rewritten as formula (3) as follows:

It can be seen from the solid line L2 in Figure 3 that the actual value a ₀ of the slope is:

Therefore, formula (3) can be rewritten as:

in

is the slope correction value

. Therefore, the processing circuit 30 is used to obtain the slope correction value according to the power difference, the intensity index difference, the correction parameter, the slope preset value and the slope correction function.

. And replacing the slope default value with the slope correction value, the linear relationship equation after slope correction is obtained:

.

如此一來便完成射頻發射機的校正，使射頻發射機作動時所發出的訊號功率其功率與強度指標之間的關係式得以符合預期。另外值得注意的是，第三功率x ₀，可以是處理電路30調整發射元件10的增益檔位A，以使射頻訊號之訊號功率符合第三功率值x ₀，也可以是處理電路30直接取第一功率值x ₁或第二功率值x ₂作為第三功率值x ₀使用。 Please refer to Figure 4 again. The dotted line L3 is the ideal linear relationship, and the solid line L4 is the actual linear relationship after slope adjustment. From Figure 4, it can be seen that the third power x ₀ corresponds to a preset intensity index value y _ref , and a third intensity index value y ₀ . When the third intensity index value y ₀ is substantially different from the intensity index preset value y _ref , the processing circuit 30 will perform power correction and compare the intensity index preset value y _ref with the third intensity index value y ref . The three intensity index values y ₀ are based on the formula: y _ref - y ₀ = c , and a power correction value c is obtained, and the power correction value c is corrected to the actual linear relationship equation. Finally, the corrected linear relationship equation is obtained as follows:

In this way, the calibration of the radio frequency transmitter is completed, so that the relationship between the signal power and the intensity index of the signal power emitted when the radio frequency transmitter is activated can meet expectations. It is also worth noting that the third power x ₀ can be obtained by the processing circuit 30 adjusting the gain gear A of the transmitting element 10 so that the signal power of the radio frequency signal complies with the third power value x ₀ , or it can be directly obtained by the processing circuit 30 The first power value x ₁ or the second power value x ₂ is used as the third power value x ₀ .

Please see Figure 1. In some embodiments, the direction of the arrow refers to the transmitting element 10 transmitting the radio frequency signal to the vector signal analyzer (Vector signal Analyzer, VSA) C for mediating the Wi-Fi signal. In some embodiments, the processing circuit 30 includes a comparison circuit 32, which is used to determine whether the first intensity index value y ₀ is substantially different from the intensity index preset value y _{ref 1} , and compare the power correction value c to the actual Correct the linear relationship.

The following is an introduction to the RF output power correction method of this case based on Figure 2 and Figure 1:

S1: Adjust a gain level of a transmitting element 10 of the radio frequency transmitter to sequentially make the two radio frequency signals emitted by the transmitting element 10 comply with a first power and a second power.

S2: Obtain a corresponding first intensity index value and a second intensity index value according to the linear relationship expression.

S3: Obtain a slope correction value based on the first power, the second power, the first intensity index value and the second intensity index value.

S4: Replace the slope preset value with the slope correction value.

The above steps S1 to S4 are the slope correction step flow of the radio frequency output power correction method. Please refer to the aforementioned radio frequency transmitter for its embodiment and related description, and will not be described again here. In some embodiments, the radio frequency output power correction method includes power correction in step S5 as follows:

S5: The first power corresponds to a preset intensity index value, a power correction value is obtained according to the intensity index preset value and the first intensity index value, and the linear relationship expression is corrected according to the power correction value.

In some embodiments, step S1 further includes: adjusting the gain level so that the signal power of the radio frequency signal emitted by the transmitting element 10 complies with a first power, and obtaining a first intensity index value according to the linear relationship. ; and adjust the gain level so that the signal power of the radio frequency signal emitted by the transmitting element 10 conforms to a second power, and obtain a second intensity index value according to the linear relationship.

In some embodiments, the slope correction value is obtained based on a slope correction function, a correction parameter, the slope preset value, the power difference value and the intensity index difference value.

，其中a為該修正參數、△x為該功率差值、△y為該強度指標差值、a _ref 為該斜率預設值、

為該斜率校正值。 In some embodiments, the slope correction function is:

, where a is the correction parameter, △ x is the power difference, △ y is the intensity index difference, a _ref is the slope preset value,

This is the slope correction value.

Although the technical content of this case has been disclosed above through various embodiments, it is not used to limit the scope of protection of this case. Any changes or modifications made by anyone familiar with the common knowledge in the field of this case without departing from the spirit of this case will fall within the scope of this case. Therefore, the scope of protection in this case should be based on the content stated in the scope of the patent application.

S1~S5: steps

Claims (8)

A radio frequency transmitter, including: a transmitting element for emitting a radio frequency signal according to a gain level and an input signal; a detection element for detecting and obtaining the signal power of the radio frequency signal; and a processing circuit , has a linear relational expression, the linear relational expression has a slope preset value, the processing circuit is used to: adjust the gain gear so that the signal power of the radio frequency signal emitted by the transmitting element meets a first power, And obtain a first strength index value according to the linear relationship expression; adjust the gain gear so that the signal power of the radio frequency signal emitted by the transmitting element conforms to a second power, and obtain a second intensity index value according to the linear relationship expression intensity index value; obtain a slope correction value according to the first power, the second power, the first intensity index value and the second intensity index value; and replace the slope default value with the slope correction value; wherein, the The processing circuit has a slope correction function and a correction parameter. According to a power difference between the first power and the second power, an intensity index difference between the first intensity index value and the second intensity index value, the correction The slope correction value is obtained from the parameters, the slope preset value and the slope correction function. The radio frequency transmitter of claim 1, wherein the detection component includes a power detection circuit and an analog-to-digital conversion circuit. The power detection circuit detects and obtains a power analog value of the radio frequency signal. The analog-to-digital conversion circuit Convert the power analog value to No. power. The radio frequency transmitter of claim 2, wherein the processing circuit includes a digital circuit, the digital circuit is used to obtain the corresponding first intensity index value or the second intensity index based on the signal power and the linear relationship expression value. The radio frequency transmitter as described in claim 3, wherein the slope correction function is:

, where a is the correction parameter, △ x is the power difference, △ y is the intensity index difference, a _ref is the slope preset value,

This is the slope correction value. The radio frequency transmitter of claim 4, wherein the first power corresponds to a preset intensity index value, and the processing circuit obtains a power correction value based on the preset intensity index value and the first intensity index value, and based on the The power correction value corrects this linear relationship. A radio frequency output power correction method is suitable for a radio frequency transmitter. The radio frequency transmitter has a linear relational expression. The linear relational expression has a slope preset value. The correction method includes: adjusting a transmitting element of the radiofrequency transmitter. Gain gears to sequentially make the two radio frequency signals emitted by the transmitting element comply with a first power and a second power; obtain a corresponding first intensity index value and a second intensity index value according to the linear relationship; Obtain a slope correction value according to the first power, the second power, the first intensity index value and the second intensity index value; and replace the slope default value with the slope correction value; wherein, the slope correction value The acquisition is based on a slope correction function, a correction parameter, the slope preset value, a power difference between the first power and the second power and the first intensity indicator. A strength index difference between the standard value and the second strength index value. The radio frequency output power correction method as described in claim 6, wherein the step of adjusting the gain gear to sequentially make the radio frequency signal emitted by the transmitting element comply with the first power and the second power includes: adjusting the gain gear position, so that the signal power of the radio frequency signal emitted by the transmitting element meets the first power, and the first intensity index value is obtained according to the linear relationship; and the gain gear is adjusted so that the signal power emitted by the transmitting element meets the first power. The signal power of the radio frequency signal conforms to the second power, and the second intensity index value is obtained according to the linear relationship. The radio frequency output power correction method as described in claim 7, wherein the slope correction function is:

, where a is the correction parameter, △ x is the power difference, △ y is the intensity index difference, a _ref is the slope preset value,

This is the slope correction value.

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