A radio frequency power detection circuit

Abstract

The application provides a radio frequency power detection circuit, comprising a detection sub-circuit, a comparator 1, a half-bridge rectification sub-circuit and a comparator 2. The radio frequency power detection circuit judges whether the input radio frequency peak power exceeds or is lower than a certain value through comparison, rectification and then comparison. The state output of the detection circuit is not affected by the pulse width and duty cycle of the radio frequency signal, accurate judgment can be performed, the radio frequency power detection circuit has the characteristics of simple structure and wide application range, and the radio frequency power detection circuit is suitable for judging whether the radio frequency input peak power of any pulse width and duty cycle form exceeds a certain value, and is suitable for judging whether the radio frequency input continuous wave signal power falls to less than a certain value for a short time.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency power detection technology, and specifically relates to a radio frequency power detection circuit. Background Technology

[0002] In radio frequency (RF) systems, it is generally necessary to evaluate RF signals to determine whether their power reaches a certain level.

[0003] There are two main ways in which the existing radio frequency power detection circuits work: one is to first rectify the pulses after the radio frequency signal is detected into DC signals and then compare them; the other is to first compare the pulses after the radio frequency signal is detected and then obtain a pulse signal to trigger the subsequent pulse broadening circuit.

[0004] For the first working method, which first rectifies the pulse after detecting the radio frequency signal into a DC signal and then compares them, such as Figure 9 As shown, this circuit has the following drawbacks: a) When the RF input is a pulse signal, the rectified voltage V3 is affected by the pulse width and duty cycle of the pulse signal. For RF signals with different pulse widths and duty cycles but the same peak power, the peak voltage output after the detector circuit and amplifier is V2. The smaller the pulse width and the smaller the duty cycle, the greater the voltage difference between V3 and V2 will be than the diode's forward voltage Vd, indicating that the rectified voltage V3 of the amplifier output V2 cannot truly reflect the peak power of the RF signal; b) When the RF input is a continuous wave signal, this circuit is not suitable for determining whether the peak power of the RF input has dropped below a certain value P in a short period of time. If there is a short-term drop in RF power, although the capacitor C in the half-bridge rectifier circuit discharges, the discharge time is insufficient, and the voltage V3 of capacitor C does not drop significantly. The comparator's output voltage V5 will not change, leading to an incorrect state judgment.

[0005] The second method, which first compares the pulses detected by the RF signal to obtain a pulse signal for triggering the subsequent pulse broadening circuit, has the following disadvantages: a) The delay time after triggering is limited by the inherent characteristics of the D flip-flop, and the external capacitor cannot be too large, resulting in an insufficient adjustment time range for the D flip-flop; b) It is susceptible to false alarms due to system noise interference. This is because after pulse comparison and amplification, any high-level signal sent to the D flip-flop will generate a high-level signal. If system noise interferes with the input of the D flip-flop, it will incorrectly output a pulse delay signal, causing a false alarm; c) This type of detection circuit is unsuitable for continuous wave RF operation. Because the detection voltage is a DC signal during continuous wave operation, after voltage comparison, it still outputs DC, and no pulse signal is input to the D flip-flop. Without a pulse output, the entire detection circuit will fail.

[0006] Therefore, it is necessary to provide a radio frequency power detection circuit to realize accurate evaluation of radio frequency signals. SUMMARY

[0007] In order to solve the above problems, the present application aims to provide a radio frequency power detection circuit to realize the purpose that the radio frequency power detection circuit is not affected by the radio frequency pulse width and duty cycle.

[0008] In order to achieve the above purpose, the present application provides the following technical solution, a radio frequency power detection circuit, the detection circuit comprises: a detection sub-circuit for performing detection of an input radio frequency signal and outputting an envelope signal V0 with the same width as the radio frequency input signal; a comparator 1 for comparing the envelope signal voltage output by the detection sub-circuit with a first reference voltage V1 and outputting a first TTL high-low level signal V1'; a half-bridge rectifier sub-circuit for performing half-bridge rectification on the first TTL high-low level signal V1' output by the comparator 1 and outputting a direct current signal V2'; a comparator 2 for comparing the direct current signal V2' output by the half-bridge rectifier sub-circuit with a second reference voltage V2 to obtain a second TTL high-low level signal V3, and performing radio frequency input power state judgment through the second TTL high-low level signal V3.

[0009] The radio frequency power detection circuit provided by the present application also has the following characteristics: the power state judgment includes judging whether the radio frequency input power is greater than a peak power threshold value or judging whether the radio frequency input continuous wave signal power drops to less than the peak power threshold value.

[0010] The radio frequency power detection circuit provided by the present application also has the following characteristics: when judging whether the radio frequency input power is greater than the peak power threshold value, the envelope signal V0 is input to the positive input terminal of the comparator 1, and the first reference voltage V1 is input to the negative input terminal of the comparator 1.

[0011] The radio frequency power detection circuit provided by the present application also has the following characteristics: when judging whether the radio frequency input continuous wave signal power drops to less than the peak power threshold value, the envelope signal V0 is input to the negative input terminal of the comparator 1, and the first reference voltage V1 is input to the positive input terminal of the comparator 1.

[0012] The radio frequency power detection circuit provided by the present application also has the following characteristics: the detection circuit further comprises an amplification sub-circuit arranged between the detection sub-circuit and the comparator 1, and the amplification sub-circuit comprises an operational amplifier 1.

[0013] The radio frequency power detection circuit provided by the present application also has the following characteristics: the detection circuit further comprises an amplification sub-circuit arranged between the comparator 1 and the half-bridge rectifier sub-circuit, and the amplification sub-circuit comprises an operational amplifier 2.

[0014] The radio frequency power detection circuit further has the following features: the detection circuit further comprises amplification sub-circuit 1 and amplification sub-circuit 2 arranged before and after the comparator 1 respectively, the amplification sub-circuit 1 comprises an operational amplifier 1, and the amplification sub-circuit 2 comprises an operational amplifier 2.

[0015] The radio frequency power detection circuit further has the following features: the half-bridge rectification sub-circuit comprises a capacitor C and a thermistor R, the resistance value of the thermistor R changes to offset the capacitance value change of the capacitor C with temperature, so that the product of the resistance value of the thermistor R and the capacitance value of the capacitor C is constant at different temperature states.

[0016] The radio frequency power detection circuit further has the following features: the first reference voltage V1 is the output of the detection circuit corresponding to a set peak value power threshold of the radio frequency input signal; and the second reference voltage V2 is the minimum value of the output voltage of the half-bridge rectification sub-circuit in a state in which the comparator 1 generates a minimum pulse width and a minimum duty cycle pulse signal when the radio frequency detection circuit is working.

[0017] The radio frequency power detection circuit further has the following features: the product of the resistance value of the thermistor R and the capacitance value of the capacitor C is greater than the length of time without radio frequency in a radio frequency pulse period.

[0018] Advantages

[0019] The radio frequency power detection circuit judges whether the input radio frequency peak value power exceeds or is lower than a certain value through comparison and rectification and then comparison. The state output of the detection circuit is not affected by the pulse width and duty cycle of the radio frequency signal, accurate judgment can be performed, the radio frequency power detection circuit has the characteristics of simple structure and wide application range, is suitable for judging whether the radio frequency input peak value power of any pulse width and duty cycle form exceeds a certain value, and is suitable for judging whether the radio frequency input continuous wave signal power falls to less than a certain value for a short time. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 A schematic diagram of a radio frequency power detection circuit;

[0022] FIG. 2 is a radio frequency detection circuit for judging whether the radio frequency input peak value power exceeds a certain value;

[0023] Figure 3 is a radio frequency detection circuit for determining whether the power of a radio frequency input continuous wave signal falls below a certain value for a short time;

[0024] Figure 4 Figure 4 is a waveform diagram of a radio frequency detection circuit for determining whether the peak power of a radio frequency input exceeds a certain value;

[0025] Figure 5 is a waveform diagram of a radio frequency detection circuit for determining whether the power of a radio frequency input continuous wave signal falls below a certain value for a short time;

[0026] Figure 6 Figure 6 is a radio frequency detection circuit with an amplifier added after the detection circuit;

[0027] Figure 7 is a radio frequency detection circuit with an amplifier added after the comparator 1;

[0028] Figure 8 is a radio frequency detection circuit with two-stage amplifiers added;

[0029] Figure 9 Figure 9 is a radio frequency detection circuit for determining after the radio frequency detection signal is rectified into a direct current signal;

[0030] Figure 10 is a working principle of the detection circuit;

[0031] Figure 11 is a waveform of a half-bridge rectifier circuit;

[0032] Figure 12 is a radio frequency detection circuit in the form of pulse stretching using a D flip-flop. DETAILED DESCRIPTION

[0033] The application will be further described below in conjunction with the drawings and embodiments, but it should be noted that these embodiments are not a limitation on the application, and equivalent transformations or substitutions of function, method, or structure made by those of ordinary skill in the art based on these embodiments are within the scope of the application.

[0034] In the description of the embodiments of the application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0035] In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implying the number of the technical features indicated. Therefore, the features defined as "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0036] The terms "mounting", "connection", "connection" should be broadly understood, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0037] The working mode of the prior art radio frequency power detection circuit mainly has two kinds: one is to compare the pulse rectified into direct current signal after the radio frequency signal is detected; the second is to obtain the pulse signal used for triggering the pulse expansion circuit in the rear stage after comparing the pulse after the radio frequency signal is detected.

[0038] For the first kind, as shown in Figure 9 , the radio frequency detection circuit judges the radio frequency detection signal into direct current signal, the specific implementation of the circuit is: the radio frequency signal is input into the detection circuit, the detection circuit outputs the envelope signal with the same width as the radio frequency input signal, the peak voltage is V1, V1 is low, generally tens of mV to hundreds of mV, the amplified signal voltage amplitude is V2 through the operational amplifier. After passing through the half-bridge rectifier circuit composed of diode D, capacitor C and resistor R, it becomes a direct current signal, the amplitude is V3, which is input into the comparator and compared with the set direct current reference voltage V4.

[0039] Among them, the reference voltage V4 represents the output voltage value of the half-bridge rectifier circuit when the radio frequency input power value is P.

[0040] If V3 is greater than V4, the comparator outputs high level, indicating that the radio frequency input power is greater than P; if V3 is less than V4, the comparator outputs low level, indicating that the radio frequency input power is less than P.

[0041] Among them, as shown in Figure 10 , the detection circuit outputs the envelope signal with the same pulse width as the radio frequency input signal,

[0042] The amplifier realizes proportional amplification of the input detection voltage.

[0043] The half-bridge rectifier circuit rectifies the input voltage signal into a direct current signal.

[0044] When there is an RF input, the detector voltage V1 is amplified to reach V2. When V2 is greater than the forward voltage Vd of diode D, diode D conducts, and capacitor C charges. When there is no RF input or V2 is less than the forward voltage Vd of diode D, diode D is cut off, and capacitor C discharges through resistor R. If capacitor C is not fully discharged during the time diode D is cut off, the rectified voltage V3 will gradually increase and stabilize after multiple charging cycles. The rectified voltage V3 is a DC signal with slight fluctuations at the top. The larger the discharge constants of capacitor C and resistor R, the smaller the fluctuations at the top of V3. Generally, the charging and discharging time constant τ of capacitor C and resistor R in the half-bridge rectifier circuit is required to be much larger than the duration of no RF input within one RF cycle, where τ = RC. Specific waveforms are shown below. Figure 11 As shown.

[0045] The existing technology has two main drawbacks:

[0046] a) When the RF input is a pulse signal, the rectified voltage V3 is affected by the pulse width and duty cycle of the pulse signal. For RF signals with different pulse widths and duty cycles but the same peak power, the peak voltage output after the detector circuit and amplifier is V2. The smaller the pulse width and the smaller the duty cycle, the greater the voltage difference between V3 and V2 will be than the diode's forward voltage Vd, indicating that the rectified voltage V3 of the amplifier output V2 cannot accurately reflect the peak power of the RF signal.

[0047] (b) When the RF input is a continuous wave signal, this circuit is not suitable for determining whether the peak power of the RF input drops below a certain value P within a short period of time. If there is a short-term RF power drop, although the capacitor C in the half-bridge rectifier circuit discharges, the discharge time is insufficient, the voltage V3 of capacitor C does not drop significantly, and the output voltage V5 of the comparator will not change, which will cause an error in the state judgment.

[0048] The second method involves obtaining a pulse voltage after RF input detection, comparing the pulse voltage with a reference to obtain a pulse signal, and then using the pulse state signal to trigger a subsequent D flip-flop. For example, Chinese Utility Model Patent CN206411202U provides an ultra-wideband bit detection circuit with adjustable delay. This technology... Figure 12As shown, the D flip-flop is a retrievable monostable multivibrator. The working principle of the D flip-flop is to adjust the pulse delay time generated after triggering by using an external capacitor and resistor. The pulse delay time is related to the charging and discharging time constant formed by the external capacitor and resistor. This technique has the following disadvantages: a) The delay time after triggering is limited by the inherent characteristics of the D flip-flop; the external capacitor cannot be too large, resulting in a narrow adjustment time range for the D flip-flop; b) It can be caused by noise interference in the system, leading to false alarms. This is because after pulse comparison and amplification, as long as a high-level signal is sent to the D flip-flop, it will generate a high-level signal. If noise enters the system, it interferes with the input of the D flip-flop, causing it to incorrectly output a pulse delay signal, resulting in a false alarm; c) This type of detection circuit is not suitable for continuous wave radio frequency operation. Because the detection voltage is a DC signal during continuous wave operation, after voltage comparison, it still outputs DC, and there is no pulse signal input to the D flip-flop. Without a pulse output, the entire detection circuit will fail.

[0049] To overcome the above shortcomings, the present invention provides an RF power detection circuit to achieve the purpose of RF power detection circuit being unaffected by RF pulse width and duty cycle.

[0050] The invention will now be further described with reference to the accompanying drawings.

[0051] like Figure 1 As shown, this embodiment of the invention provides an RF power detection circuit, which includes: a detector sub-circuit for receiving RF input and outputting an envelope signal V0 with the same width as the RF input signal; a comparator 1 for comparing the envelope signal voltage output by the detector sub-circuit with a first reference voltage V1 and outputting a first TTL high / low level signal V1'; a half-bridge rectifier sub-circuit for performing half-bridge rectification on the first TTL high / low level signal V1' output by the comparator 1 and outputting a DC signal V2'; and a comparator 2 for comparing the DC signal V2' output by the half-bridge rectifier sub-circuit with a second reference voltage V2 to obtain a second TTL high / low level signal V3, and using the second TTL high / low level signal V3 to determine the RF input power status.

[0052] In some embodiments, the power state determination includes determining whether the RF input power is greater than the peak power threshold or whether the RF input continuous wave signal power drops to below the peak power threshold.

[0053] In some embodiments, when determining whether the RF input power is greater than the peak power threshold, the envelope signal V0 is input to the positive input terminal of comparator 1, and the first reference voltage V1 is input to the negative input terminal of comparator 1.

[0054] In some embodiments, when judging whether the power of the radio frequency input continuous wave signal drops to less than the peak power threshold value, the envelope signal V0 is input to the negative input terminal of the comparator 1, and the first reference voltage V1 is input to the positive input terminal of the comparator 1.

[0055] In some embodiments, the detection circuit further comprises an amplification sub-circuit arranged between the detection sub-circuit and the comparator 1, and the amplification sub-circuit comprises an operational amplifier 1. The operational amplifier 1 arranged between the detection sub-circuit and the comparator 1 realizes the amplification of the output voltage of the detection sub-circuit as an amplification sub-circuit.

[0056] In some embodiments, the detection circuit further comprises an amplification sub-circuit arranged between the comparator 1 and the half-bridge rectification sub-circuit, and the amplification sub-circuit comprises an operational amplifier 2. The operational amplifier 2 arranged between the comparator 1 and the half-bridge rectification sub-circuit realizes the improvement of the driving capability of the comparator 1.

[0057] In some embodiments, the detection circuit further comprises amplification sub-circuits 1 and 2 arranged before and after the comparator 1 respectively, the amplification sub-circuit 1 comprises an operational amplifier 1, and the amplification sub-circuit 2 comprises an operational amplifier 2.

[0058] In some embodiments, the half-bridge rectification sub-circuit comprises a capacitor C and a thermistor R, and the resistance value of the thermistor R changes to offset the capacitance value change of the capacitor C with temperature, so that the product of the resistance value of the thermistor R and the capacitance value of the capacitor C is constant at different temperature states.

[0059] In some embodiments, the first reference voltage V1 is the output of the detection circuit corresponding to the set peak power threshold value of the radio frequency input signal; and the second reference voltage V2 is the minimum value of the output voltage of the half-bridge rectification circuit in the state that the comparator 1 generates the minimum pulse signal with the minimum pulse width and the minimum duty cycle when the radio frequency detection circuit is working.

[0060] In some embodiments, the product of the resistance value of the thermistor R and the capacitance value of the capacitor C is greater than the length of time without radio frequency in a radio frequency pulse period. The technical solution provided in this embodiment ensures that the half-bridge rectification circuit has a voltage output greater than the reference voltage V2 in a pulse period.

[0061] The working principle of the technical solution provided in the foregoing embodiments is as follows:

[0062] As Figure 1As shown, the radio frequency signal is input to the detection circuit, the detection circuit outputs an envelope signal with the same width as the radio frequency input signal, and the voltage is V0; the envelope signal is input to the comparator 1, and after comparison with the reference voltage V1, the comparator 1 outputs high and low levels V1' synchronized with the envelope signal, and after the half-bridge rectifier circuit composed of the diode D, the capacitor C and the resistor R, it becomes a direct current signal V2' input to the comparator 2 and compared with the set direct current reference voltage V2. Whether the radio frequency input peak power reaches a certain value is judged by judging the high and low levels of the comparator 2 output.

[0063] The present application is described in segments according to different functions completed by the detection circuit.

[0064] 1) Circuit description of the detection circuit and the comparator 1

[0065] a) The detection circuit is connected to the + input of the comparator 1, and the reference voltage V1 is connected to the - input of the comparator 1

[0066] As shown, when the circuit is used to judge whether the radio frequency input peak power exceeds a certain value, the detection signal is input to the + input of the comparator 1, and the reference voltage V1 is connected to the - input of the comparator 1, which is used in the following way: Figure 2 The detection voltage V0 is input to the + input of the comparator 1, and the reference voltage V1 is connected to the - input of the comparator 1.

[0067] The reference voltage V1 is the detection circuit output corresponding to the set radio frequency input signal peak power threshold value.

[0068] The reference voltage V1 should be greater than the detection signal amplitude V0' interference generated after the interference signal from the detection circuit.

[0069] When the radio frequency input peak power exceeds the threshold value, the comparator 1 outputs high level; when the radio frequency input peak power does not reach the threshold value, the comparator 1 outputs low level.

[0070] b) The detection circuit is connected to the - input of the comparator 1, and the reference voltage V1 is connected to the + input of the comparator 1

[0071] As shown, when the circuit is used to judge whether the radio frequency input continuous wave signal power falls below a certain value for a short time, the detection signal is input to the - input of the comparator 1, and the reference voltage V1 is connected to the + input of the comparator 1. The following way is used:

[0072] Figure 3 The reference voltage V1 is the detection circuit output corresponding to the set radio frequency input signal peak power threshold value, i.e. the detection circuit output corresponding to the falling power threshold value.

[0073] The reference voltage V1 is the detection circuit output corresponding to the set radio frequency input signal peak power threshold value, i.e. the detection circuit output corresponding to the falling power threshold value.

[0074] ​The reference voltage V1 should be greater than the amplitude V0' of the interference signal after the interference signal from the self-detection circuit.

[0075] When the power of the radio frequency input continuous wave signal drops to less than the threshold value for a short time, the comparator 1 outputs a high level; when the power of the radio frequency input continuous wave signal is greater than the threshold value for a time period, the detection voltage will be greater than the reference voltage V1, and the comparator 1 outputs a low level.

[0076] 2) Half-bridge rectifier circuit and subsequent circuit description

[0077] After the pulse voltage V1' passes through the half-bridge rectifier circuit composed of the diode D, the capacitor C and the resistor R, it becomes a direct current signal V2'. The direct current signal V2' is input into the comparator 2 and compared with the set direct current reference voltage V2. Whether the radio frequency power reaches a certain value is determined by judging the high and low levels of the output V3 of the comparator 2.

[0078] When the diode D, the capacitor C and the resistor R of the half-bridge rectifier circuit are selected, the pulse voltage V1' containing a high level passes through the half-bridge rectifier circuit, and V2' has a voltage value greater than 0V.

[0079] If the radio frequency input is a continuous wave, and the output voltage of the detection circuit is greater than V1, the voltage of V2' is the maximum, which is V2', and the voltage difference between V2' and V1' is only the voltage drop of the diode D, which is Vd, Vd = V2' - V1'.

[0080] If the radio frequency input is in the form of a pulse greater than the set threshold value, or the radio frequency continuous wave signal appears a short-time power drop below the threshold value, the voltage difference between V2' and V1' will be greater than Vd. The smaller the pulse width and the smaller the duty cycle of the comparator 1 output, the greater the voltage difference between V2' and V1' will be than Vd.

[0081] When the radio frequency detection circuit is working, the output voltage of the half-bridge rectifier circuit is V2' when the comparator 1 outputs the minimum pulse width and the minimum duty cycle. min V2' min needs to be greater than the direct current reference voltage V2.

[0082] Theoretically, V2 can be 0V, but in the actual circuit, there will be certain system interference, and the set value of V2 cannot be too small. If the interference signal from V1' passes through the half-bridge rectifier circuit, it will also output a direct current voltage, which is V2' interference. In order to eliminate the interference signal, when the radio frequency detection circuit is designed, the reference voltage V2 should be greater than the rectified interference voltage V2' interference and less than or equal to the minimum rectified voltage V2' min interval.

[0083] The specific waveforms are shown in Figure 4 or Figure 5 .

[0084] When the reference voltage V2 and the rectified voltage V2' are connected to the + input or - input of the comparator 2 respectively, the output of the comparator 2 represents different meanings. The logic relationship is shown in Table 1 and Table 2. Table 1 is the meaning represented by the output of the comparator 2 in the radio frequency detection circuit for judging whether the radio frequency pulse signal exceeds a certain value; Table 2 is the meaning represented by the output of the comparator 2 in the radio frequency detection circuit for judging whether the continuous wave radio frequency signal appears a short time power drop to less than a certain value.

[0085] Table 1

[0086]

[0087] Table 2

[0088]

[0089] At the same time, if the output voltage of the detection circuit is low, an amplifier composed of an operational amplifier can be added between the detection circuit and the comparator 1, as shown in Figure 6 .

[0090] At the same time, if the capacitance C in the half-bridge rectifier circuit is large, an amplification circuit composed of an operational amplifier can be added between the comparator 1 and the half-bridge rectifier circuit to improve the driving ability and provide more energy for the charging of the capacitance C, as shown in Figure 7 .

[0091] At the same time, if the output voltage of the detection circuit is low and the capacitance C in the half-bridge rectifier circuit is large, an amplification circuit composed of an operational amplifier can be added between the detection circuit and the comparator 1, and at the same time, an amplification circuit composed of an operational amplifier can be added between the comparator 1 and the half-bridge rectifier circuit to improve the driving ability and provide more energy for the charging of the capacitance C, as shown in Figure 8 .

[0092] At the same time, the capacitance C will change in capacity under high and low temperature conditions, and the resistance R can use a thermistor with resistance value opposite to the change trend of the capacitance C, so that the RC discharge time constant remains consistent under high and low temperature conditions, preventing false reporting.

[0093] At the same time, the reference voltage V1 can be adjusted in amplitude for judging different radio frequency input peak powers. For example, different voltage values are switched using a switch form.

[0094] At the same time, the time constant of the capacitance C and the resistance R of the half-bridge rectifier circuit is required to be much larger than the length of time without radio frequency in a radio frequency period, so as to ensure that the half-bridge rectifier circuit has a voltage output greater than the reference voltage V2 within a pulse period.

[0095] The above merely describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application. The above merely describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A radio frequency power detection circuit, characterized by, The detection circuit comprises: a detection sub-circuit for detecting an input radio frequency signal and outputting an envelope signal V0 with the same width as the radio frequency input signal; a comparator 1 for comparing the envelope signal voltage output by the detection sub-circuit with a first reference voltage V1 and outputting a first TTL high-low level signal V1'; a half-bridge rectification sub-circuit for half-bridge rectifying the first TTL high-low level signal V1' output by the comparator 1 and outputting a direct current signal V2'; a comparator 2 for comparing the direct current signal V2' output by the half-bridge rectification sub-circuit with a second reference voltage V2 and obtaining a second TTL high-low level signal V3, and judging the radio frequency input power state through the second TTL high-low level signal V3, the first reference voltage V1 is the detection circuit output corresponding to the set peak power threshold value of the radio frequency input signal; and the second reference voltage V2 is the minimum value of the output voltage of the half-bridge rectification sub-circuit in the state of the minimum pulse width and the minimum duty cycle pulse signal generated by the comparator 1 when the radio frequency detection circuit is working.

2. The radio frequency power detection circuit of claim 1, wherein, The power state judgment includes judging whether the radio frequency input power is greater than the peak power threshold value or judging whether the radio frequency input continuous wave signal power drops to less than the peak power threshold value.

3. The radio frequency power detection circuit of claim 2, wherein, When judging whether the radio frequency input power is greater than the peak power threshold value, the envelope signal V0 is input to the positive input terminal of the comparator 1, and the first reference voltage V1 is input to the negative input terminal of the comparator 1.

4. The radio frequency power detection circuit of claim 2, wherein, When judging whether the radio frequency input continuous wave signal power drops to less than the peak power threshold value, the envelope signal V0 is input to the negative input terminal of the comparator 1, and the first reference voltage V1 is input to the positive input terminal of the comparator 1.

5. The radio frequency power detection circuit of claim 1, wherein, The detection circuit further comprises an amplification sub-circuit arranged between the detection sub-circuit and the comparator 1, and the amplification sub-circuit comprises an operational amplifier 1.

6. The radio frequency power detection circuit of claim 1, wherein, The detection circuit further comprises an amplification sub-circuit arranged between the comparator 1 and the half-bridge rectification sub-circuit, and the amplification sub-circuit comprises an operational amplifier 2.

7. The radio frequency power detection circuit of claim 1, wherein, The detection circuit further comprises amplification sub-circuits 1 and 2 arranged before and after the comparator 1 respectively, the amplification sub-circuit 1 comprises an operational amplifier 1, and the amplification sub-circuit 2 comprises an operational amplifier 2.

8. The radio frequency power detection circuit of claim 1, wherein, The half-bridge rectification sub-circuit comprises a capacitor C and a thermistor R, the resistance value of the thermistor R changes to offset the capacitance value change of the capacitor C with temperature, so that the product of the resistance value of the thermistor R and the capacitance value of the capacitor C is constant at different temperature states.

9. The radio frequency power detection circuit of claim 8, wherein, The product of the resistance value of the thermistor R and the capacitance value of the capacitor C is greater than the length of time without radio frequency in one radio frequency pulse period.

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