CN100473996C - Apparatus for detecting linear index of power amplifier - Google Patents
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Abstract
The present invention discloses a detection equipment of linear index of power amplifier. Said detection equipment includes power detection circuit and microprocessor. The described power detection circuit is used for receiving output signal of power amplifier to be detected, converting power of main channel signal into first digital signal, converting the power of adjacent channel signal obtained by filtration into second digital signal and inputting the first digital signal and second digital signal into the microprocessor; the described microprocessor can utilize the first digital signal, second digital signal and correspondent relationship of preset digital signal and power to obtain the main channel signal power and adjacent channel signal power and calculate the linear index value of power amplifier. Said invention also provides a method for detecting linear index of power amplifier.
Description
Technical Field
The invention relates to the field of power amplifiers, in particular to a detection device for a linear index of a power amplifier.
Background
In recent years, with the rapid development of communication systems, the requirement for linearity of a power amplifier in the communication system is greatly increased, and therefore the requirement for linear debugging of the power amplifier is also increased correspondingly.
A debugging system in the prior art is shown in fig. 1, and the debugging system includes a to-be-tested power amplifier, a radio frequency signal source, a dc power supply, an ammeter, an attenuator, and a spectrometer, where the to-be-tested power amplifier includes a power amplifier tube, a control circuit, an adjustable bias circuit, an input matching circuit, and an output matching circuit. The radio frequency signal source generates a radio frequency signal as an input signal of the power amplifier to be measured, the direct current power supply provides direct current for the power amplifier to be measured, the ammeter is used for monitoring the working current of the power amplifier to be measured, the attenuator attenuates the output signal of the power amplifier to ensure that the power of a signal input to the frequency spectrograph is within an allowable measurement range of the frequency spectrograph, and the frequency spectrograph is used for measuring the frequency spectrum characteristics of the output signal of the power amplifier, such as power, adjacent channel power leakage ratio (ACLR) value and the like. The control circuit in the power amplifier to be tested is used for controlling the on-off state of the bias circuit according to the input control signal, so as to control the working state of the power amplifier to be on or off, and the control circuit generally adopts an Erasable Programmable Logic Device (EPLD).
By using the debugging system shown in fig. 1, first, under the condition of turning off the output of the radio frequency signal source, the bias voltage of the power amplifier is adjusted to a specified range, and the quiescent current is ensured to be the recommended value of the power amplifier device manual. And then turning on a radio frequency signal source, inputting a radio frequency signal to the power amplifier, enabling an output signal of the power amplifier to reach the specified power, and adjusting the bias voltage of the power amplifier to enable the output linearity of the power amplifier to reach the optimum. Since the gain of the power amplifier is changed by changing the bias voltage, the input power and the bias voltage of the power amplifier need to be adjusted repeatedly many times to meet the requirement of the output power and linearity of the power amplifier.
In the existing debugging process, a signal amplified by a power amplifier to be tested is usually input into a frequency spectrograph after being attenuated by an attenuator, and the output power and a linear index of the power amplifier, such as ACLR or third-order intermodulation (IM3), are measured by the frequency spectrograph. The ACLR is a ratio of adjacent channel leakage power to main channel carrier power in the output signal amplified by the power amplifier, and the IM3 is a ratio of third-order intermodulation power to useful signal power.
As shown in fig. 2, the circuit for measuring power and linearity of the spectrometer includes an attenuator, a down converter, a local oscillator frequency synthesizer, an analog-to-digital (a/D) converter, and a microprocessor, wherein the microprocessor includes a Fast Fourier Transform (FFT) module and an integration module. When the output signal of the power amplifier is input into the frequency spectrograph, the output signal is firstly attenuated by the attenuator; then, the down converter mixes the frequency according to the attenuated signal and the local oscillator signal output by the local oscillator frequency synthesizer, and the A/D converter converts the analog signal into a digital signal; then, Fourier transform is carried out through an FFT module to obtain a frequency spectrum; and performing power integration through an integration module to obtain the power of the main channel signal and the power of the adjacent channel signal, and calculating the ACLR according to the power of the main channel signal and the power of the adjacent channel signal.
Because the frequency spectrograph adopts an integral calculation method to obtain the power value of each part to be measured, the time for measuring the power and the linear index of the output signal of the power amplifier is longer when the frequency spectrum is finished once. Moreover, because the adjustment and the measurement of the bias voltage of one power amplifier need to be carried out for multiple times and the measurement of the output linear index needs to be carried out for multiple times, the adjustment and the measurement of one power amplifier can be finished only by using a frequency spectrograph in tens of minutes on average, and the speed of large-scale adjustment and measurement of the power amplifier is further greatly reduced.
Disclosure of Invention
In view of the above, the present invention provides two kinds of apparatuses for detecting a linear index of a power amplifier, which aims to increase a speed of detecting the linear index of the power amplifier so as to increase a speed of tuning and detecting the power amplifier.
In order to achieve the first object, the invention provides the following technical scheme:
a detection device for linear indexes of a power amplifier comprises a coupler, a first power detector, a first A/D converter, a local oscillator frequency synthesizer, a down converter, a middle frequency band filter, a second power detector, a second A/D converter and a microprocessor; wherein,
the coupler is used for coupling the output signal of the power amplifier into a main channel signal for detecting the carrier power of the main channel and an adjacent channel signal for detecting the leakage power of the adjacent channel, the main channel signal is input into the first power detector, and the adjacent channel signal is input into the down converter;
the first power detector is used for converting the signal power coupled to the first power detector by the coupler into a first analog voltage and inputting the first analog voltage into the first A/D converter;
the first A/D converter is used for converting the analog voltage from the first power detector into a first digital signal and inputting the first digital signal into the microprocessor;
the local oscillator frequency synthesizer is controlled by the frequency of the microprocessor to output local oscillator signals with corresponding frequencies to the down converter, wherein the local oscillator signal frequency (spill) when the upper sideband power is measured is (fc-fs + df) or (fc + fs-df); the local oscillation signal frequency flodown when measuring the lower sideband power is flodown ═ fc-fs-df or flodown ═ fc + fs + df; wherein fc is the main channel frequency, df is the upper sideband frequency or the offset of the lower sideband frequency and the main channel frequency, and fs is the center frequency of the response of the intermediate frequency band-pass filter;
the down converter is used for obtaining an upper-band intermediate-frequency signal or a lower-band intermediate-frequency signal through frequency conversion according to the upper-band local oscillator signal or the lower-band local oscillator signal and a signal coupled to the down converter by the coupler, and sending the upper-band intermediate-frequency signal or the lower-band intermediate-frequency signal to the intermediate-frequency band-pass filter;
the intermediate frequency band-pass filter is used for filtering the upper sideband intermediate frequency signal or the lower sideband intermediate frequency signal and then sending the upper sideband intermediate frequency signal or the lower sideband intermediate frequency signal to the second power detector;
the second power detector is used for converting the intermediate frequency signal power from the intermediate frequency band-pass filter into a second analog voltage and inputting the second analog voltage into the second A/D converter;
the second A/D converter is used for converting the second analog voltage from the second power detector into a second digital signal and inputting the second digital signal into the microprocessor;
and the microprocessor is used for acquiring the power of the main channel signal and the power of the adjacent channel signal according to the first digital signal, the second digital signal and the preset corresponding relation between the digital signal and the power, and calculating the linear index value of the power amplifier.
In the above solution, the detection apparatus further includes a first attenuator, configured to attenuate the main channel signal coupled by the coupler to an operating range of the first power detector.
In the above solution, the detecting apparatus further includes a second attenuator, configured to attenuate the adjacent channel signal coupled by the coupler to a working range of the down converter.
In the above scheme, the detection apparatus further includes an intermediate frequency amplifier, configured to compensate and amplify the adjacent channel signal output by the intermediate frequency band-pass filter, and input the compensated and amplified adjacent channel signal to the second power detector.
In the above scheme, the detection apparatus includes a second intermediate frequency band-pass filter, configured to further filter the adjacent channel signal output by the intermediate frequency amplifier, and input the adjacent channel signal obtained through the further filtering to the second power detector.
In the above scheme, the detection apparatus further includes a second intermediate frequency amplifier, configured to compensate and amplify the adjacent channel signal output by the second intermediate frequency band-pass filter, and input the compensated and amplified adjacent channel signal to a second power detector.
In the above scheme, the detection apparatus further includes an attenuator, configured to attenuate an output signal of the power amplifier and send the attenuated output signal to the coupler.
In order to achieve the second object, the invention comprises the following technical scheme:
a detection device for linear indexes of a power amplifier comprises a local oscillator frequency synthesizer, a down converter, an intermediate frequency band-pass filter, a controllable attenuator, a second power detector, a second A/D converter and a microprocessor; wherein,
the local oscillator frequency synthesizer is controlled by the frequency of the microprocessor to output a first local oscillator signal and a second local oscillator signal to the down converter in a time-sharing manner, wherein the frequency of the first local oscillator signal flo is flo-fc or flo-fc + fs, and the frequency of the second local oscillator signal floup is floup-fc-fs + df or floup-fc + fs-df when the upper sideband power is measured; when the lower sideband power is measured, the frequency flodown of the second local oscillation signal is flodown ═ fc-fs-df or flodown ═ fc + fs + df; wherein fc is the main channel frequency, df is the upper sideband frequency or the offset of the lower sideband frequency and the main channel frequency, and fs is the center frequency of the response of the intermediate frequency band-pass filter;
the down converter is used for obtaining a first intermediate frequency signal through down conversion according to the first local oscillation signal and the output signal of the power amplifier and inputting the first intermediate frequency signal into the intermediate frequency band-pass filter, and obtaining a second intermediate frequency signal through down conversion according to the second local oscillation signal and the output signal of the power amplifier and inputting the second intermediate frequency signal into the intermediate frequency band-pass filter;
the intermediate frequency band-pass filter is used for filtering the first intermediate frequency signal to obtain a main channel signal and inputting the main channel signal into the controllable attenuator, and filtering the second intermediate frequency signal to obtain an adjacent channel signal and inputting the adjacent channel signal into the controllable attenuator;
the controllable attenuator is used for carrying out large attenuation on the main channel signal output by the intermediate frequency band-pass filter and then inputting the main channel signal into the second power detector, and carrying out small attenuation or no attenuation on the adjacent channel signal output by the intermediate frequency band-pass filter and then inputting the adjacent channel signal into the second power detector;
the second power detector is used for converting the main channel signal power output by the controllable attenuator into a first analog voltage and inputting the first analog voltage to the second A/D converter, and converting the adjacent channel signal power output by the controllable attenuator into a second analog voltage and inputting the second analog voltage to the second A/D converter;
the second A/D converter is used for converting the first analog voltage into a first digital signal and inputting the first digital signal to the microprocessor, and converting the second analog voltage into a second digital signal and inputting the second digital signal to the microprocessor;
and the microprocessor is used for acquiring the power of the main channel signal and the power of the adjacent channel signal according to the first digital signal, the second digital signal and the preset corresponding relation between the digital signal and the power, and calculating the linear index value of the power amplifier.
In the above solution, the detecting device further includes an intermediate frequency amplifier, configured to compensate and amplify the intermediate frequency signal output by the intermediate frequency band filter, and input the compensated and amplified intermediate frequency signal to the controllable attenuator.
In the foregoing solution, the detection apparatus further includes a second intermediate frequency band-pass filter, configured to further filter the intermediate frequency signal output by the controllable attenuator, and input the intermediate frequency signal after further filtering to the second power detector.
In the foregoing solution, the detection apparatus further includes a second intermediate frequency amplifier, configured to compensate and amplify the intermediate frequency signal output by the second intermediate frequency band-pass filter, and send the compensated and amplified intermediate frequency signal to the second power detector.
In the above scheme, the detection apparatus further includes an attenuator, configured to attenuate an output signal of the power amplifier and send the attenuated output signal to the down converter.
According to the scheme, the power of each part of the output signal of the power amplifier is directly converted into the voltage by using a specific simple device, the corresponding power value is obtained according to the voltage, the power and the linear index of the output signal of the power amplifier can be rapidly measured, the speed of detecting the linear index of the power amplifier is improved, and the speed of adjusting and measuring the power amplifier is improved. Furthermore, the invention provides a device for simultaneously measuring the power of the main channel signal and the power of the adjacent channel signal, thereby meeting the requirements of different application environments. The device adopted by the invention is simple and low in price, so that the cost of the debugging and testing power amplifier is greatly reduced, and the device is suitable for large-scale use. Meanwhile, the device provided by the invention can also be integrated in base station equipment to dynamically detect and control the linear index of the power amplifier.
Drawings
FIG. 1 is a schematic diagram of a debugging system in the prior art;
FIG. 2 is a schematic diagram of a circuit for measuring signal power and linearity indicator in a spectrometer;
FIG. 3 is a diagram illustrating an apparatus for detecting a linear index according to a first embodiment of the present invention;
FIG. 4 is a schematic diagram of the spectrum of an IF bandpass filter when measuring upper sideband power;
FIG. 5 is a schematic diagram of the spectrum of an IF bandpass filter when measuring lower sideband power;
FIG. 6 is a graph showing the relationship between frequencies when measuring upper sideband power;
FIG. 7 is a graph showing the relationship between frequencies when measuring lower sideband power;
FIG. 8 is a schematic diagram of the detecting device of FIG. 3 with the addition of a first-stage IF bandpass filter;
FIG. 9 is a diagram illustrating an apparatus for detecting a linear index according to a second embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail by referring to the following examples.
Different from the integral calculation method of the existing frequency spectrograph, the power detector is adopted to convert the power of the radio-frequency signal into the analog voltage, then the corresponding power value is obtained according to the analog voltage, and the output linearity of the power amplifier is calculated according to the power value.
As shown in fig. 3, the detecting device used in the first embodiment of the present invention includes: attenuator 201, coupler 202, first attenuator 210, first power detector 211, first a/D converter 212, second attenuator 203, down converter 204, local oscillator frequency synthesizer 205, intermediate frequency band pass filter 206, intermediate frequency amplifier 207, second power detector 208, second a/D converter 209, and microprocessor 213. Wherein the first power detector 211 and the second power detector 208 may be the same type of detector or different types of detectors, and the first a/D converter 212 and the second a/D converter 209 may be the same type of a/D converter or different types of a/D converters. A first power detection circuit composed of the first attenuator 210, the first power detector 211, and the first a/D converter 212 is used to detect the power of the main channel signal; a second power detection circuit composed of the second attenuator 203, the down converter 204, the local oscillator frequency synthesizer 205, the intermediate frequency band pass filter 206, the intermediate frequency amplifier 207, the second power detector 208 and the second a/D converter 209 is used for detecting the power of the adjacent channel signal.
The function of the modules in fig. 3 is as follows: the attenuator 201 attenuates the signal output by the power amplifier to be detected and inputs the signal into the coupler 202; the coupler 202 divides the signal into two parts, one part is input into a first power detection circuit for measuring the power of the main channel signal, and the other part is input into a second power detection circuit for measuring the power of the adjacent channel signal; the first attenuator 210 attenuates the signal input from the coupler 202 to within the linear detection range of the first power detector 211 to ensure the accuracy of the measurement; the first power detector 211 is a Root Mean Square (RMS) value power detector for converting the power of the radio frequency signal into an analog voltage; the first a/D converter 212 converts the analog voltage into a digital signal and sends the digital signal to the microprocessor 213; the second attenuator 203 attenuates the signal input from the coupler 202 into the linear range of the down-converter 204, and then inputs the signal into the down-converter 204; the local oscillator frequency synthesizer outputs a local oscillator signal with the frequency flo to the down converter 204 under the frequency control of the microprocessor; the down converter 204 obtains an intermediate frequency signal with a center frequency of fi after frequency mixing according to the input radio frequency signal and the local oscillator signal, wherein when flo is higher than the radio frequency signal center frequency fc, fi is fc-flo, and when flo is lower than fc, fi is flo-fc; the intermediate frequency band-pass filter 206 filters the intermediate frequency signal to obtain an intermediate frequency signal in a required frequency range; because the loss generated by the intermediate frequency band-pass filter is relatively large, the signal is compensated and amplified by using the intermediate frequency amplifier 207 and then input into the second power detector 208; the second power detector 208 converts the power of the filtered intermediate frequency signal into an analog voltage; the second A/D converter 209 converts the analog voltage into a digital signal and sends the digital signal to the microprocessor 213; the microprocessor 213 may be a single chip or a digital signal processing chip (DSP), and is connected to the a/D converter and the local frequency synthesizer via a common digital signal input pin, and respectively calculates the power Po of the main channel and the power of the adjacent channel according to the digital signals input by the first a/D converter 212 and the second a/D converter 209.
When the input signal is a signal transmitted in a specific time slot, such as a signal of a Time Division Duplex (TDD) communication system, the present invention may input an external synchronization trigger signal to the microprocessor 213 through the digital signal input pin, and the microprocessor 213 controls the first a/D converter 212 and the second a/D converter 209 to synchronously operate in the time slot for transmitting the signal, so as to ensure the accuracy of the result. Furthermore, the microprocessor 213 can be directly connected with related instruments such as a radio frequency signal generator and the like and a control circuit of the power amplifier, the switching working states of the related instruments and the power amplifier can be directly controlled according to the external synchronous trigger signal, and the power and the linearity index of the output signal of the power amplifier can be synchronously measured.
In addition, the microprocessor can be further connected with a computer through an interface, and the interface can adopt a parallel port, a serial port or a Universal Serial Bus (USB) interface and the like to communicate with the computer, so that the power Po, the ACLR and other related data of the main channel signals are transmitted to the computer, and other related control, display and record of the related data are facilitated.
The measurement process using the apparatus shown in fig. 2 is as follows:
before measurement, the detection device is first calibrated to obtain a detailed correspondence, for example a correspondence table or a functional relationship, between the power of the actual input signal and the detection voltage of the power detector, which is represented by the corresponding digital signal input to the microprocessor, to ensure the accuracy of the measurement. And after calibration, the correspondence is saved in the microprocessor 213.
In the measurement process, when the output signal of the power amplifier to be measured is input to the apparatus, the microprocessor 213 controls to measure the power of the main channel signal and the power of the adjacent channel signal and calculate the adjacent channel power leakage ratio.
Because the main channel has two adjacent channels, namely an upper sideband and a lower sideband, the local frequency needs to be controlled in the measurement process so that the lower converter outputs signals with proper frequency in a time-sharing manner to measure the power of the upper sideband and the power of the lower sideband respectively. Let the main channel frequency of the input signal be fc, the local oscillator frequency output by the local oscillator frequency synthesizer 205 be flo, the main channel frequency of the signal obtained after down-conversion by the down-converter 204 becomes fi, when flo is less than fc, fi is fc-flo, when flo is greater than fc, fi is flo-fc. Because the offset between the upper sideband and the main channel frequency and the offset between the lower sideband and the main channel frequency are df and are known quantities, the center frequency of the response of the intermediate frequency band-pass filter is fs, so that fs is fi + df when the upper sideband power is measured, and fs is fi-df when the lower sideband power is measured. Fig. 4 and 5 show the frequency spectrum diagrams of the if band-pass filter when measuring the upper and lower sideband power, respectively.
When measuring the upper sideband power, the microprocessor 213 controls the local oscillator frequency flo output by the local oscillator frequency synthesizer to be floup, where floup is less than fc, and the value of floup can be determined by the relationship fi ═ fc-floup at the down converter and the relationship fi ═ fs-df at the intermediate frequency band pass filter: and (3) floup fc-fi fc- (fs-df) fc-fs + df. The relationship between the above frequencies is shown in fig. 6. Of course, it is also possible to assume that the flow is greater than fc, and then fc + fi + fc + fs-df is determined from fi-fc and fi-fs-df.
The microprocessor 213 obtains the power Po1 of the main channel and the power Pup of the upper sideband adjacent channel signal from the digital signals input from the first a/D converter 212 and the second a/D converter 209, and calculates the adjacent channel power leakage ratio Pup/Po1 at this time.
When measuring the lower sideband power, the microprocessor 213 controls the local oscillator frequency flo output by the local oscillator frequency synthesizer to be flodown, where flodown is less than fc, and the value of flodown can be determined by the relationship fi ═ fc-flodown at the down converter and the relationship fi ═ fs + df at the intermediate frequency band pass filter: flodown ═ fc-fi ═ lc- (fs + df) ═ fc-fs-df. The relationship between the above frequencies is shown in fig. 7. Of course, it is also possible to take flodown greater than fc, and then flodown fc + fi fc + fs + df is determined from fi ═ flodown-fc and fi ═ fs + df.
The microprocessor 213 obtains the power Po2 of the main channel and the power Pdown of the lower sideband adjacent channel signal according to the digital signals input by the first a/D converter 212 and the second a/D converter 209, and calculates the adjacent channel power leakage ratio Pdown/Po2 at this time.
The ACLR value may be calculated by measuring only the power Pup of the upper sideband and the power Po1 of the main channel signal and calculating Pup/Po1, or may be calculated by measuring only the power Pdown of the lower sideband and the power Po2 of the main channel signal and calculating Puo/Po 2. Further, after measuring Pup, Po1, Pdown and Po2, the larger of Pup and Pdown is taken as the power of the adjacent channel signal, i.e. the power of the adjacent channel signal is taken to be equal to max (Pup, Pdown), the average value of Po1 and Po2 is taken as the power of the main channel signal, i.e. the power of the main channel signal is taken to be equal to (Po1+ Po2)/2, and then ACLR is calculated to be equal to max (Pup, Pdown)/((Po1+ Po 2)/2).
In the apparatus shown in fig. 3, when the power of the adjacent channel signal is measured, the rejection ratio of the signal deviated from the predetermined frequency needs to be larger than the adjacent channel power leakage ratio, and generally needs to be larger by 10dB or more. If the single-stage if band-pass filter cannot achieve the desired rejection ratio, a multi-stage cascade may be used in the circuit, such as the circuit shown in fig. 8, which uses a two-stage cascade, and fig. 8 adds a second if band-pass filter 214 and an if amplifier 215 on the basis of fig. 3 to form a two-stage cascade to achieve the desired signal rejection ratio. The measurement method using this apparatus is the same as the measurement method using the apparatus shown in fig. 3, and will not be described again here.
In the first embodiment, two circuits are used to measure the power of the main channel signal and the power of the adjacent channel signal at the same time, and in the second embodiment, the same circuit is used to measure the power of the main channel signal and the power of the adjacent channel signal in a time-sharing manner.
A second embodiment of the apparatus of the present invention is shown in fig. 9, and comprises: attenuator 201, local oscillator frequency synthesizer 205, down converter 204, intermediate frequency band pass filter 206, intermediate frequency amplifier 207, controllable attenuator 218, third intermediate frequency amplifier 217, second intermediate frequency band pass filter 214, second intermediate frequency amplifier 215, second power detector 208, second a/D converter 209, and microprocessor 213. The circuit diagram shown in fig. 9 is less extensive than the circuit diagram shown in fig. 3, i.e. the coupler 202, the second attenuator 203, the first attenuator 210, the first power detector 211 and the first a/D converter 212 are omitted, i.e. the branch dedicated to measuring the power of the main channel signal is omitted; there is an additional controllable attenuator 218 and a third intermediate frequency amplifier 217 than in the circuit diagram shown in fig. 3. The controllable attenuator 218 controls the power attenuation value according to the high and low levels of the control pins, and the different combinations of the high and low levels of the control pins form attenuation values with different powers, the microprocessor 213 controls the controllable attenuator through the expansion circuit, performs large attenuation when measuring the power of the main channel signal, and performs small attenuation or no attenuation when measuring the power of the adjacent channel signal; the third intermediate frequency amplifier 217 has the effect of mainly compensating for the large attenuation of the controllable attenuator 218.
In the second embodiment, when measuring the power of the adjacent channel signal, the microprocessor controls the local oscillation frequency output by the local oscillation frequency synthesizer to be the same as that in the first embodiment, and in the process of measuring the power of the adjacent channel signal, the microprocessor controls the controllable attenuator to perform small attenuation or no attenuation on the signal, and the power value of the adjacent channel signal is measured.
When the power of the main channel signal is measured, if flo is less than fc, determining that flo is fc-fi which is the fc-fs at the moment by a relational expression fi which is fc-flo at a down converter and a relational expression fi which is fs at an intermediate frequency band-pass filter; if flo is larger than fc, then fi is flo-fc and fi is fs, and then flo + fi is fc + fs determined. The microprocessor controls the local oscillator frequency synthesizer to output signals with the local oscillator frequency of flo, and controls the controllable attenuator to perform large attenuation, so that the power value of the main channel can be measured.
The microprocessor calculates the ACLR value according to the measured power value of the adjacent channel signal and the power value of the main channel signal by using the method described in the first embodiment.
In addition, the apparatus in the first and second embodiments of the present invention can be used to measure not only the power leakage ratio of the adjacent channel signal, but also other linear indexes such as third-order intermodulation (IM 3). When the IM3 is measured, the power of the main channel signal and the power of the intermodulation part are measured, and the measurement method is exactly the same as the power of the main channel signal and the power of the adjacent channel signal when the ACLR is measured. In contrast, since the IM3 tests two continuous waves separated by 1MHz in the useful signal, the bandwidth of the filter used in the device needs to be less than 1 MHz.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (12)
1. The detection device for the linearity index of the power amplifier is characterized by comprising a coupler, a first power detector, a first A/D converter, a local oscillator frequency synthesizer, a down converter, an intermediate frequency band-pass filter, a second power detector, a second A/D converter and a microprocessor; wherein,
the coupler couples the output signal of the power amplifier into a main channel signal for detecting the carrier power of the main channel and an adjacent channel signal for detecting the leakage power of the adjacent channel, the main channel signal is input into the first power detector, and the adjacent channel signal is input into the down converter;
the first power detector is used for converting the signal power coupled to the first power detector by the coupler into a first analog voltage and inputting the first analog voltage into the first A/D converter;
the first A/D converter is used for converting the analog voltage from the first power detector into a first digital signal and inputting the first digital signal into the microprocessor;
the local oscillator frequency synthesizer is controlled by the frequency of the microprocessor to output local oscillator signals with corresponding frequencies to the down converter, wherein the local oscillator signal frequency (spill) when the upper sideband power is measured is (fc-fs + df) or (fc + fs-df); the local oscillation signal frequency flodown when measuring the lower sideband power is flodown ═ fc-fs-df or flodown ═ fc + fs + df; wherein fc is the main channel frequency, df is the upper sideband frequency or the offset of the lower sideband frequency and the main channel frequency, and fs is the center frequency of the response of the intermediate frequency band-pass filter;
the down converter is used for obtaining an upper-band intermediate-frequency signal or a lower-band intermediate-frequency signal through frequency conversion according to the upper-band local oscillator signal or the lower-band local oscillator signal and a signal coupled to the down converter by the coupler, and sending the upper-band intermediate-frequency signal or the lower-band intermediate-frequency signal to the intermediate-frequency band-pass filter;
the intermediate frequency band-pass filter is used for filtering the upper sideband intermediate frequency signal or the lower sideband intermediate frequency signal and then sending the upper sideband intermediate frequency signal or the lower sideband intermediate frequency signal to the second power detector;
the second power detector is used for converting the intermediate frequency signal power from the intermediate frequency band-pass filter into a second analog voltage and inputting the second analog voltage into the second A/D converter;
the second A/D converter is used for converting the second analog voltage from the second power detector into a second digital signal and inputting the second digital signal into the microprocessor;
and the microprocessor is used for acquiring the power of the main channel signal and the power of the adjacent channel signal according to the first digital signal, the second digital signal and the preset corresponding relation between the digital signal and the power, and calculating the linear index value of the power amplifier.
2. The detection apparatus of claim 1, further comprising a first attenuator for attenuating the main channel signal coupled by the coupler to an operating range of the first power detector.
3. The detection apparatus according to claim 1 or 2, wherein the detection apparatus further comprises a second attenuator for attenuating the coupler-coupled adjacent channel signal to the operating range of the down converter.
4. The detecting device according to claim 3, further comprising an intermediate frequency amplifier for offset-amplifying the adjacent channel signal outputted from the intermediate frequency band-pass filter, and inputting the offset-amplified adjacent channel signal to the second power detector.
5. The detection apparatus according to claim 4, wherein the detection apparatus comprises a second if band-pass filter for further filtering the adjacent channel signal outputted from the if amplifier, and inputting the adjacent channel signal obtained by the further filtering into the second power detector.
6. The detecting device according to claim 5, wherein the detecting device further comprises a second intermediate frequency amplifier for compensation amplifying the adjacent channel signal outputted from the second intermediate frequency band pass filter, and inputting the compensated and amplified adjacent channel signal to a second power detector.
7. The detection apparatus according to claim 1, further comprising an attenuator for attenuating the output signal of the power amplifier and sending the attenuated signal to the coupler.
8. The detection device for the linearity index of the power amplifier is characterized by comprising a local oscillator frequency synthesizer, a down converter, an intermediate frequency band-pass filter, a controllable attenuator, a second power detector, a second A/D converter and a microprocessor; wherein,
the local oscillator frequency synthesizer is controlled by the frequency of the microprocessor to output a first local oscillator signal and a second local oscillator signal to the down converter in a time-sharing manner, wherein the frequency of the first local oscillator signal flo is flo-fc or flo-fc + fs, and the frequency of the second local oscillator signal floup is floup-fc-fs + df or floup-fc + fs-df when the upper sideband power is measured; when the lower sideband power is measured, the frequency flodown of the second local oscillation signal is flodown ═ fc-fs-df or flodown ═ fc + fs + df; wherein fc is the main channel frequency, df is the upper sideband frequency or the offset of the lower sideband frequency and the main channel frequency, and fs is the center frequency of the response of the intermediate frequency band-pass filter;
the down converter is used for obtaining a first intermediate frequency signal through down conversion according to the first local oscillation signal and the output signal of the power amplifier and inputting the first intermediate frequency signal into the intermediate frequency band-pass filter, and obtaining a second intermediate frequency signal through down conversion according to the second local oscillation signal and the output signal of the power amplifier and inputting the second intermediate frequency signal into the intermediate frequency band-pass filter;
the intermediate frequency band-pass filter is used for filtering the first intermediate frequency signal to obtain a main channel signal and inputting the main channel signal into the controllable attenuator, and filtering the second intermediate frequency signal to obtain an adjacent channel signal and inputting the adjacent channel signal into the controllable attenuator;
the controllable attenuator is used for carrying out large attenuation on the main channel signal output by the intermediate frequency band-pass filter and then inputting the main channel signal into the second power detector, and carrying out small attenuation or no attenuation on the adjacent channel signal output by the intermediate frequency band-pass filter and then inputting the adjacent channel signal into the second power detector;
the second power detector is used for converting the main channel signal power output by the controllable attenuator into a first analog voltage and inputting the first analog voltage to the second A/D converter, and converting the adjacent channel signal power output by the controllable attenuator into a second analog voltage and inputting the second analog voltage to the second A/D converter;
the second A/D converter is used for converting the first analog voltage into a first digital signal and inputting the first digital signal to the microprocessor, and converting the second analog voltage into a second digital signal and inputting the second digital signal to the microprocessor;
and the microprocessor is used for acquiring the power of the main channel signal and the power of the adjacent channel signal according to the first digital signal, the second digital signal and the preset corresponding relation between the digital signal and the power, and calculating the linear index value of the power amplifier.
9. The detecting device according to claim 8, wherein the detecting device further comprises an intermediate frequency amplifier for compensation amplifying the intermediate frequency signal outputted from the intermediate frequency band pass filter and inputting the compensated amplified intermediate frequency signal to the controllable attenuator.
10. The detecting device according to claim 9, wherein the detecting device further comprises a second if band-pass filter for further filtering the if signal outputted from the controllable attenuator and inputting the further filtered if signal to the second power detector.
11. The detecting device according to claim 10, further comprising a second if amplifier for compensation-amplifying the if signal outputted from the second if band-pass filter and sending the compensated-amplified if signal to the second power detector.
12. The detecting device of claim 8, wherein the detecting device further comprises an attenuator for attenuating the output signal of the power amplifier and sending the attenuated signal to the down converter.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB200510069293XA CN100473996C (en) | 2005-05-13 | 2005-05-13 | Apparatus for detecting linear index of power amplifier |
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| CNB200510069293XA CN100473996C (en) | 2005-05-13 | 2005-05-13 | Apparatus for detecting linear index of power amplifier |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101377531B (en) * | 2007-08-29 | 2011-09-14 | 海华科技股份有限公司 | Output power detecting structure with direction coupler and direction coupler |
| CN101893682B (en) * | 2010-06-25 | 2012-12-05 | 珠海和佳医疗设备股份有限公司 | Method for testing resonant power amplifying circuit |
| CN102386852B (en) * | 2011-07-19 | 2015-04-29 | 成都芯通科技股份有限公司 | Method for amplifying digital multi-carrier power and power amplifier for realizing same |
| CN103744010B (en) * | 2013-12-26 | 2017-01-18 | 中国电子科技集团公司第三十六研究所 | An automatic testing system and an automatic testing method of a continuous wave radio frequency power amplifier |
| CN104316760B (en) * | 2014-10-10 | 2017-07-11 | 中国电子科技集团公司第四十一研究所 | A kind of dominant frequency signal determinating circuit and decision method for being applied to microwave frequency counter |
| CN104579450A (en) * | 2014-12-05 | 2015-04-29 | 泉州市琪祥电子科技有限公司 | Small-sized indoor repeater with functions of automatically detecting linear state of amplifier and carrying out intelligent processing |
| CN106411435B (en) * | 2016-09-29 | 2019-06-11 | 宇龙计算机通信科技(深圳)有限公司 | A kind of RF transmitter and method of adjust automatically ACLR |
| CN108267650A (en) * | 2016-12-30 | 2018-07-10 | 上海优立检测技术股份有限公司 | A kind of radiated immunity test method of high accuracy |
| CN114553335A (en) * | 2020-11-25 | 2022-05-27 | 上海畅恒自动化设备有限公司 | Fast full-channel power detection circuit structure for self-adaptive channel selection |
| CN114629457B (en) * | 2021-12-30 | 2024-10-11 | 北京无线电计量测试研究所 | Device and method for controlling frequency source and frequency source |
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Effective date of registration: 20151021 Address after: 100083 Haidian District, Xueyuan Road, No. 29, Patentee after: DATANG MOBILE COMMUNICATIONS EQUIPMENT Co.,Ltd. Patentee after: SHANGHAI DATANG MOBILE COMMUNICATIONS EQUIPMENT Co.,Ltd. Address before: 100083 Haidian District, Xueyuan Road, No. 29, Patentee before: DATANG MOBILE COMMUNICATIONS EQUIPMENT Co.,Ltd. |
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