Passive frequency mixing circuit and communication equipment

Abstract

The invention discloses a passive frequency mixing circuit and communication equipment. The mixer circuit comprises a first switch tube and a first filter. The grid electrode of the first switch tube is used for inputting a first signal, and the first signal is used for controlling the on-off of the first switch tube. The drain electrode of the first switch tube is used for being connected with the first end of the first filter, and the second end of the first filter is used for being grounded. The source electrode of the first switch tube is used for inputting a second signal, the source electrode of the first switch tube is also used for outputting a third signal, and the third signal is a signal obtained by mixing the first signal and the second signal. The invention provides a passive frequency mixing circuit and communication equipment, and aims of high linearity and low loss of a passive frequency mixer can be fulfilled.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a passive mixing circuit and communication equipment. Background Art

[0002] The mixer is a key component for frequency conversion in wireless communication equipment and is also a basic unit of wireless communication transceivers. Among them, the wireless communication receiver uses a mixer to down-convert the received radio frequency (RF) signal to an intermediate frequency signal or a zero intermediate frequency signal for processing, and the wireless communication transmitter uses a mixer to up-convert the intermediate frequency or zero intermediate frequency signal to a radio frequency signal to facilitate antenna transmission.

[0003] Modern communication systems have higher and higher requirements for communication speed and range, which makes the bandwidth of communication signals wider and wider, and the signal power and RF frequency higher and higher. Passive mixers are usually realized by combining diode bridge stacks and baluns, but this type of passive mixer cannot meet the performance requirements of low loss. Summary of the invention

[0004] The present application provides a passive mixer circuit and a communication device, which can achieve the goals of high linearity and low loss of a passive mixer.

[0005] In a first aspect, the present application provides a mixing circuit, which includes a first switch tube and a first filter. The gate of the first switch tube is used to input a first signal, and the first signal is used to control the on and off of the first switch tube. The drain of the first switch tube is used to connect to the first end of the first filter, and the second end of the first filter is used to ground. The source of the first switch tube is used to input a second signal, and the source of the first switch tube is also used to output a third signal, and the third signal is a signal obtained by mixing the first signal and the second signal.

[0006] In this solution, the mixing of the first signal and the second signal is achieved by controlling the on and off of the first switch tube through the first signal, which can expand the power dynamic range of the mixer. By grounding the drain of the first switch tube to form a reflection circuit, the frequency conversion loss caused by feedthrough can be reduced. A first filter is also added to the drain of the first switch tube, which can filter the mixed signal output by the first switch tube to reduce in-band fluctuations.

[0007] In a possible implementation, the frequency mixing circuit further includes a first resistor. The second end of the first filter is specifically used to be connected to the first end of the first resistor, and the second end of the first resistor is used to be grounded.

[0008] In this solution, a reflection circuit is formed by connecting the first resistor to the second end of the first filter and grounding the first resistor, thereby reducing the frequency conversion loss caused by feed-through.

[0009] In a possible implementation, the mixing circuit further includes a second filter. The gate of the first switch tube is used to input the first signal, including: the gate of the first switch tube is used to connect to the first end of the second filter, and the second end of the second filter is used to input the first signal.

[0010] In this solution, a second filter is added to the gate of the first switch tube to select the frequency of the input first signal and reduce the in-band fluctuation.

[0011] In a possible implementation, the mixing circuit further includes a first circulator. The source of the first switch tube is specifically used to connect to the first end of the first circulator. The second end of the first circulator is used to input the second signal, and the third end of the first circulator is used to output the third signal.

[0012] In this solution, the isolation between the second signal and the third signal is increased by adding a first circulator to the source of the first switch tube.

[0013] In a possible implementation, the mixing circuit further includes a second circulator, a second switch tube and a third filter. The third end of the first circulator is used to output the third signal, including: the third end of the first circulator is used to connect to the first end of the second circulator, and the second end of the second circulator is used to output the third signal. The third end of the second circulator is used to connect to the source of the second switch tube. The gate of the second switch tube is used to input a fourth signal, and the fourth signal is used to control the on and off of the second switch tube to achieve mixing of the fourth signal and the fifth signal, and the fifth signal is input from the second end of the second circulator. The output time of the third signal is different from the input time of the fifth signal. The drain of the second switch tube is used to connect to the first end of the third filter, and the second end of the third filter is used to be grounded.

[0014] In this solution, a second circulator, a second switch tube and a third filter are added. The second switch tube is used to mix the fourth signal and the fifth signal. The second circulator is also used to increase the isolation between the signals. The first switch tube and the second switch tube in this solution can both mix the signals. In addition, the first circulator and the second circulator can control the flow direction of the signals and increase the isolation between the signals. Therefore, the mixing circuit shown in this solution can have the functions of up-conversion and down-conversion.

[0015] In a possible implementation, the frequency mixing circuit further includes a second resistor. The second end of the third filter is specifically used to be connected to the first end of the second resistor, and the second end of the second resistor is used to be grounded.

[0016] In this solution, a reflection circuit is formed by connecting a second resistor to the second end of the third filter and grounding the second resistor.

[0017] In a possible implementation, the mixing circuit further includes a fourth filter. The gate of the second switch tube is used to input a fourth signal, including: the gate of the second switch tube is used to connect to a first end of the fourth filter, and a second end of the fourth filter is used to input the fourth signal.

[0018] In this solution, a fourth filter is added to the gate of the second switch tube to select the frequency of the input fourth signal and reduce the in-band fluctuation.

[0019] In a possible implementation, the mixing circuit further includes a fifth filter. The second end of the first circulator is used to input the second signal, including:

[0020] The second end of the first circulator is specifically used to connect to the first end of the fifth filter, and the second end of the fifth filter is used to input the second signal.

[0021] In this solution, by connecting the fifth filter to the source of the first switch tube, the second signal input to the first switch tube is filtered to reduce the in-band fluctuation.

[0022] In a possible implementation, the mixing circuit further includes a sixth filter. The source of the first switch tube is also used to output a third signal, including:

[0023] The source of the first switch tube is specifically used to be connected to the first end of the sixth filter, and the second end of the sixth filter is used to output the third signal.

[0024] In this solution, by connecting the sixth filter to the source of the first switch tube, the sixth signal output by the first switch tube is filtered to reduce the high-order harmonics in the output signal.

[0025] In a possible implementation, the first signal is a local oscillator signal, the second signal is a baseband signal or an intermediate frequency signal, and the third signal is a radio frequency signal. The mixer circuit is used to up-convert the second signal to obtain the third signal.

[0026] In this solution, the first signal is a local oscillator signal, the second signal is a baseband signal or an intermediate frequency signal, and the third signal is a radio frequency signal. The above-mentioned mixing circuit can realize up-conversion of the second signal.

[0027] In a possible implementation, the first signal is a local oscillator signal, the second signal is a radio frequency signal, and the third signal is a baseband signal or an intermediate frequency signal. The mixer circuit is used to down-convert the second signal to obtain the third signal.

[0028] In this solution, the first signal is a local oscillator signal, the second signal is a radio frequency signal, and the third signal is a baseband signal or an intermediate frequency signal. The above-mentioned mixing circuit can realize down-conversion of the second signal.

[0029] In a second aspect, the present application provides a circuit board, comprising the mixing circuit shown in any one of the first aspects.

[0030] In a third aspect, the present application provides a mixer, comprising the mixing circuit shown in any one of the first aspects.

[0031] In a fourth aspect, the present application provides a communication device, comprising the mixing circuit shown in any one of the first aspects.

[0032] The solutions provided in the second to fourth aspects include the mixing circuit provided in the first aspect, and thus can achieve the same or corresponding beneficial effects as the corresponding mixing circuit in the first aspect, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background technology, the drawings required for use in the embodiments of the present application or the background technology will be described below.

[0034] Figure 1A and Figure 1B A schematic diagram of a radio frequency subsystem is provided for an embodiment of the present application;

[0035] Figure 2 A schematic diagram of a square wave signal according to an embodiment of the present application;

[0036] Figure 3 A frequency spectrum diagram after mixing provided in an embodiment of the present application;

[0037] Figure 4 A schematic diagram of the relationship between mixer indicators provided in an embodiment of the present application;

[0038] Figure 5 A schematic diagram of a mixer circuit provided in an embodiment of the present application;

[0039] Figure 6 A schematic diagram of another mixer circuit provided in an embodiment of the present application;

[0040] Fig. 7A , Figure 7B , Figure 8, Fig.10 A schematic diagram of another mixer circuit provided in an embodiment of the present application;

[0041] Fig. 9A A schematic diagram of up-conversion loss provided in an embodiment of the present application;

[0042] Fig. 9B A schematic diagram of the relationship between OIP3 and operating frequency provided in an embodiment of the present application;

[0043] Fig.11A A schematic diagram of another up-conversion loss provided in an embodiment of the present application;

[0044] Fig. 11B A schematic diagram of down-conversion loss provided in an embodiment of the present application;

[0045] Fig. 11C Another schematic diagram of the relationship between OIP3 and operating frequency provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] The embodiments described in this application are only part of the embodiments of this application, not all of the embodiments. Those skilled in the art will appreciate that, with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0047] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. In the present application, "at least one" refers to one or more, and "a plurality of" refers to two or more. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments described herein can be implemented in a sequence other than the contents illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0048] The working principle and performance indicators of the mixer are first introduced by way of example.

[0049] 1. Mixer

[0050] The mixer in the embodiment of the present application refers to a common component in the radio frequency circuit, which is used to perform frequency conversion on the target signal. While converting the carrier frequency of the target signal to a fixed frequency, the characteristics of the target signal are ensured to remain unchanged. The mixer is a key component of the signal transceiver, which is used to up-convert the baseband signal or the intermediate frequency signal to generate the radio frequency signal. Or down-convert the radio frequency signal to generate the baseband signal or the intermediate frequency signal.

[0051] In order to better introduce the function and working principle of the mixer, the embodiment of the present application exemplarily provides a schematic diagram of a radio frequency subsystem, such as Figure 1A and Figure 1B shown.

[0052] Figure 1A The radio frequency subsystem shown is used to up-convert the baseband or intermediate frequency signal and output a radio frequency signal. Figure 1A The components include digital to analog converter (DAC), mixer, power amplifier (PA) and antenna. Among them, DAC is used to convert the digital signal to be sent into an analog signal. The analog signal obtained after conversion is called baseband signal or intermediate frequency (IF) signal. The mixer is used to up-convert the received baseband signal or IF signal to generate a radio frequency (RF) signal. PA is used to amplify the power of the received RF signal so that the RF signal has higher transmission energy and a longer transmission distance. The antenna is used to transmit the RF signal output by the PA.

[0053] Figure 1A The connection relationship between the components is that the output of the DAC is connected to the first input of the mixer ( Figure 1A The output port of the mixer ( Figure 1A The port corresponding to "2" in the figure) is connected to the input of the PA, the output of the PA is connected to the antenna, and the second input of the mixer ( Figure 1A The port corresponding to "3" in the figure is used to input the local oscillator (LO) signal.

[0054] Figure 1A The mixer shown is specifically used to up-convert a baseband or IF signal input to the mixer so that the carrier frequency of the baseband or IF signal is equal to the frequency of the LO signal.

[0055] Figure 1B The RF subsystem shown is used to down-convert the RF signal and output a baseband signal or an IF signal. Figure 1BThe components include analog to digital converter (ADC), mixer, low noise amplifier (LNA) and antenna. Among them, ADC is used to convert the received baseband signal or IF signal into a digital signal. The mixer is used to down-convert the received RF signal to generate a baseband signal or IF signal. LNA is used to amplify the received RF signal with low noise to increase the sensitivity of the RF subsystem receiving the signal. The antenna is used to transmit the RF signal output by the PA.

[0056] Figure 1B The connection relationship of each component is that the antenna is connected to the input end of the LNA, and the first output end of the LNA is connected to the first input end of the mixer ( Figure 1B The output port of the mixer ( Figure 1B The port corresponding to "2" in the figure) is connected to the input of the ADC, and the second input of the mixer ( Figure 1A The port corresponding to "3" in the figure is used to input the local oscillator (LO) signal.

[0057] Figure 1B The mixer shown is specifically used to down-convert the RF signal input to the mixer to obtain a baseband signal or an IF signal.

[0058] Above Figure 1A and Figure 1B The RF subsystems shown can be on the same device, chip, or board or on different devices, chips, or boards. Figure 1A and Figure 1B The RF subsystems shown are on the same device, chip, or board. Figure 1A and Figure 1B The LO signals in the embodiment of the present application can be the same signal or different signals. Figure 1A and Figure 1B Are they on the same device, chip, or circuit board? Figure 1A and Figure 1B There is no restriction on whether the LO signals in are the same signal.

[0059] Figure 1A and Figure 1B The functions of the mixer and the connection relationship between the mixer and other components in the radio frequency subsystem are introduced by way of example. Next, the working principle of the mixer is introduced by way of example.

[0060] 2. Working principle of mixer

[0061] The mixer can be understood as a multiplier. For example, after the RF signal and LO signal input to the mixer are multiplied, a signal containing difference frequency and sum frequency components is output at the IF port. The calculation formula is as follows:

[0062]

[0063]

[0064] Among them, V IF (t) represents the signal output from the IF port, V LO Represents the maximum amplitude of the LO signal in the input mixer, V RF Indicates the maximum amplitude of the RF signal in the input mixer. LO is the angular velocity of the LO signal, w RF is the angular velocity of the RF signal. is the phase of the LO signal, is the phase of the RF signal. The IF port outputs the difference frequency component signal as The signal outputted by the IF port as the combined frequency component is

[0065] For example, the IF signal and the LO signal input to the mixer may be multiplied to output a signal including difference frequency and sum frequency components at the RF port, as shown in the calculation formula (1):

[0066]

[0067] Among them, V RF (t) represents the signal output from the RF port, V IF Indicates the maximum amplitude of the IF signal in the input mixer, w IF is the angular velocity of the IF signal, is the phase of the IF signal. For other symbols, please refer to the relevant description of formula (1) and will not be repeated here. The signal expression of the difference frequency component output by the RF port is: The signal expression of the combined frequency component output by the RF port is:

[0068] Exemplarily, if the LO signal is a square wave signal, and the amplitudes in the positive and negative half axes are equal, the Fourier expansion of the LO signal is:

[0069]

[0070] Here, n is an odd number greater than 1.

[0071] Substituting formula (3) into formula (1) we can get V IF The expression of (t) is shown in formula (4):

[0072]

[0073] Here, n is an odd number greater than 1.

[0074] According to formula (4), when the LO signal is a square wave signal and both the positive and negative half cycles are used, the ideal conversion loss of the mixer is 2*10*log(2 / π)=-3.92dB.

[0075] Similarly, we can substitute formula (3) into formula (1) to get V RF For the specific implementation, please refer to formula (4), which will not be described here.

[0076] For ease of understanding, the present application embodiment provides a schematic diagram of a square wave signal, such as Figure 2 shown. Figure 2 The expression of the square wave signal shown is Wherein, n is an odd number greater than 1, T(t) represents the amplitude of the square wave signal, and the remaining parameters refer to the relevant description of the aforementioned formula (1), which will not be repeated here. Figure 2 The square wave signal shown has no even harmonics.

[0077] In one possible implementation, the input mixer (such as Figure 1B The RF signal is V RF (t) = V RF cos(ω RF t), where V RF represents the maximum amplitude of the RF signal in the input mixer, w RF is the angular velocity of the RF signal.

[0078] RF signal V RF (t) and square wave signal V LO (t) The signal expression of the output after mixing is as follows:

[0079]

[0080] in, represents the feedthrough of the RF signal through the mixer, It represents the second harmonic of the RF signal after mixing. Indicates the 4th harmonic of the RF signal after mixing.

[0081] like Figure 3 As shown, it is a frequency spectrum diagram after mixing provided by an embodiment of the present application. Figure 3 The angular velocity in RF corresponds to the component in formula (5) Figure 3The angular velocity in is RF-LO or RF+LO, which corresponds to the component in formula (5) as Figure 3 The angular velocity in is 3LO-RF or 3LO+RF, which corresponds to the component in formula (5) as The angular velocity of the LO signal is greater than the angular velocity of the RF-LO, but less than the angular velocity of the RF signal.

[0082] 3. Mixer loss model

[0083] The embodiment of the present application also provides a model of mixer conversion loss, and the loss model is shown in formula (6):

[0084] L total =L fie-diss +L tube-para +L mis-match +L conductor-diss (6)

[0085] Among them, L total It represents the total loss of mixer frequency conversion. fre-diss is the loss caused by useless frequency. From the above description, we can know that L fre-diss About 3.92dB. tube-para It is the additional loss caused by the parasitic parameters of the tube core, mainly caused by the internal switch tube of the mixer. mis-match L is the circuit loss caused by the mixer input and output mismatch. conductor-diss It is the conductor loss, which is mainly caused by the internal circuit (conductor) of the mixer.

[0086] 4. One decibel compression output power

[0087] The one decibel compression output power in the embodiment of the present application is also referred to as P 1dB , P 1dB It means that mixers, amplifiers and other devices have a linear dynamic range. Within this range, the output power of the device increases linearly with the input power. As the input power of the device increases, it will enter the nonlinear region of the device, causing the output power of the device to no longer increase linearly with the increase of input power. The output power of the device that is 1dB lower than the linear gain is usually called the output power P. 1dB Normally, when the output power of the device exceeds P 1dB In this case, the output power will quickly enter a maximum or fully saturated state.

[0088] 5. Third-order intercept point (IP3)

[0089] When a dual-tone signal (f1 and f2) is input into a mixer, the many combined frequency components generated by the nonlinearity of the mixer may include 2f1-f2 and 2f2-f1 (generated by the cubic terms of the nonlinear devices in the mixer) in addition to the fundamental component. The interference of the combined components caused by the mutual modulation of the dual-tone signal to the useful signal is called intermodulation distortion, also known as third order intermodulation (IM3).

[0090] IP3 can also be divided into input third-order intermodulation (in third-order intercept point, IIP3) and output third-order intermodulation (out third-order intercept point, OIP3). The unit of third-order intermodulation is dBm. The IP3 of a mixer is a constant determined by its own nonlinearity. IP3 simply describes the linearity of a mixer and has nothing to do with the size of the input signal or the gain of the mixer itself.

[0091] IP3 and IM3 also have the following relationship, for example: IIP3 = P in +0.5×IM3,OIP3=P out +0.5×IM3=IIP3+G. Among them, P in is the input power of the mixer, P out is the output power of the mixer, G is the linear gain of the mixer, P out =P in +G.

[0092] In order to show P more clearly in , P out 、OIP3、IIP3、P 1dB For the relationship between G, IM3 and the difference between output power and IM3 (IMD), please refer to Figure 4 , Figure 4 A schematic diagram of the relationship between mixer indicators provided in an embodiment of the present application.

[0093] like Figure 4 As shown, it includes a horizontal axis, a vertical axis, a solid line representing the fundamental frequency component, and a third-order intermodulation frequency component. Among them, the horizontal axis represents P in , in dBm. The vertical axis represents P out, in dBm. The solid line representing the fundamental frequency component has a slope of 1 and the starting point coordinates are (0, G). The solid line representing the third-order intermodulation frequency component has a slope of 3 and intersects with the solid line representing the fundamental frequency component at point P, and the coordinates of point P are (IIP3, OIP3). 1dB The power output is 1dB lower than the linear gain. IMD (dBc) means the power output is 1dB lower than the linear gain. in Under the same conditions, the difference between the output power of the fundamental frequency component and the output power of the third-order intermodulation frequency component, the output power corresponding to the third-order intermodulation frequency component is IM3.

[0094] The above content is an exemplary introduction to the working principle and performance indicators of the mixer. Figure 5 , a schematic diagram of a mixer circuit is shown.

[0095] like Figure 5 The mixing circuit shown includes two circuits and three ports. The two circuits include a diode bridge stack for frequency conversion and a balun for single-ended and differential conversion. One of the three ports is connected to the diode bridge stack, and the other two ports are connected to the balun. The port connected to the diode bridge stack is used to receive the LO signal, and the two ports connected to the balun are used to receive / send the IF signal and the RF signal respectively. In order to integrate the passive mixer on chip, the balun generally adopts Marchand Balun.

[0096] Figure 5 The mixing circuit shown has advantages over other topologies (e.g., single-tube mixer, single-balanced mixer, and double-double-balanced mixer) in terms of conversion loss, isolation, spurious, and cost. Figure 5 The mixer circuit shown also has some obvious disadvantages, such as:

[0097] 1. Figure 5 The Marchand Balun used in the mixer circuit shown requires a transmission line length that is proportional to the wavelength of the input signal (approximately a quarter-wavelength transmission line), and its operating bandwidth is inversely proportional to the transmission line width. When the signal wavelength is long and the operating bandwidth is wide, the balun routing loss will increase.

[0098] 2. Figure 5 The on-resistance of the diode in the mixer circuit shown is exponentially related to the input voltage. As the input signal power increases (the corresponding input voltage will also increase), the on-resistance of the diode will increase sharply. This characteristic will increase the signal loss on the one hand, and on the other hand, due to its nonlinear characteristics, it will cause Figure 5 The mixer shown has poor linearity.

[0099] therefore, Figure 5 The mixer circuit shown cannot meet the performance requirements of high power and high linearity.

[0100] To improve mixer linearity, see Figure 6 . Figure 6 The mixer circuit shown in the figure makes the field effect transistor (FET) work in the linear resistance region through appropriate biasing, thereby extending the linearity of the mixer.

[0101] like Figure 6 The mixer shown includes a local oscillator, a matching circuit, a switch tube, a combiner / transformer, an RF signal source, an IF signal receiver / load, and a drain bias voltage source (optional). The drain bias voltage source is used to make the switch tube work in the linear resistance region, thereby improving Figure 6 The linearity of the mixer is shown.

[0102] but, Figure 6 The mixer shown also has some obvious disadvantages:

[0103] 1. When the switch tube works in the triode region, the intermodulation between signals can be reduced. Therefore, it is necessary to increase the bias voltage to ensure that the switch tube does not cross the region, and at the same time, the amplitude of the RF signal is required to be small.

[0104] 2. Because the RF signal and the IF signal / baseband signal are both at the drain of the switch tube, without adding DC bias, Figure 6 The mixer shown will have significant insertion loss.

[0105] In view of the problems of large insertion loss and poor linearity of the above-mentioned mixer, the embodiment of the present application exemplarily proposes another mixer that can reduce the insertion loss of the mixer and improve the linearity.

[0106] like Fig. 7A , which is a schematic diagram of another mixer circuit provided in an embodiment of the present application. Fig. 7A The mixer circuit shown includes a first switch tube and a first filter, wherein the gate of the first switch tube is used to input a first signal, the drain of the first switch tube is connected to a first end of the first filter, and the second end of the first filter is open. The source of the first switch tube is used to input a second signal or output a third signal, and the third signal is a signal obtained by mixing the first signal and the second signal.

[0107] In a possible implementation, the first filter is a high-pass filter, which is used to provide a suitable time delay for a signal passing through the filter.

[0108] In a possible implementation, the first signal is used to control the on or off of the first switch tube, so that the first signal and the second signal are mixed.

[0109] In a possible implementation, the first signal is a square wave signal, which is divided into a positive half-cycle square wave signal and a negative half-cycle square wave signal, and the amplitudes of the positive / negative half-cycle square wave signals are equal. In the process of mixing the first signal and the second signal once, usually only the mixing of the second signal and a half-cycle square wave signal can be achieved. For example, in the process of mixing the first signal and the second signal once, the mixing of the second signal and the positive half-cycle square wave signal is achieved. If the mixed signal obtained by the mixing is directly output, since only the mixing of the second signal and a half-cycle square wave signal is performed, the power of the output signal will be greatly lost.

[0110] Exemplarily, the first signal is a square wave signal, and the second signal is received from the source of the first switching tube. The second signal is first mixed with the positive half-cycle square wave signal of the first signal through the first switching tube, and the mixed signal (including harmonics of multiple frequencies and the second signal obtained due to filter feedthrough) is output from the drain of the first switching tube, and the signal is called the first mixed signal.

[0111] Exemplarily, when the second signal is an intermediate frequency or baseband signal, the first filter is a high-pass filter, which is used to pass the second signal and block the radio frequency signal in the first mixed signal. Since the first filter cannot pass the radio frequency signal, the first filter forms a reflection circuit relative to the radio frequency signal, and the radio frequency signal in the first mixed signal will be reflected back to the first switch tube and finally output as part of the third signal.

[0112] The output end of the first filter is grounded, which also constitutes a reflection circuit. The second signal passing through the first filter will return to the first filter again and enter the first switch tube. It can be understood that the filter will cause a certain delay to the signal during the filtering process. The second signal in the first mixing signal is output from the drain of the first switch tube and enters the first switch tube again, passing through the first filter twice in total. By adjusting the parameters of the first filter, the filtering delay of the first filter on the signal is controlled, so that when the second signal in the first mixing signal enters the first switch tube again, the first signal is a negative half-cycle square wave signal, and the mixed signal of the second signal and the negative half-cycle square wave signal is output from the source of the first switch tube, and the signal is called the second mixing signal. The RF signal reflected back to the first switch tube and the second mixing signal together constitute the third signal.

[0113] Exemplarily, when the second signal is a radio frequency signal, the first filter may be a high-pass filter or a band-pass filter, which is used to pass the second signal and block the intermediate frequency signal and the baseband signal in the first mixed signal. Since the first filter cannot pass the intermediate frequency signal and the baseband signal, the first filter forms a reflection circuit relative to the intermediate frequency signal and the baseband signal, and the intermediate frequency signal and the baseband signal in the first mixed signal will be reflected back to the first switch tube, and finally output as part of the third signal.

[0114] The output end of the first filter is grounded, which also constitutes a reflection circuit. The second signal passing through the first filter will return to the first filter again and enter the first switch tube. It can be understood that the filter will cause a certain delay to the signal during the filtering process. The second signal in the first mixing signal is output from the drain of the first switch tube and enters the first switch tube again, passing through the first filter twice in total. By adjusting the parameters of the first filter, the filtering delay of the first filter on the signal is controlled, so that when the second signal in the first mixing signal enters the first switch tube again, the first signal is a negative half-cycle square wave signal, and the mixed signal of the second signal and the negative half-cycle square wave signal is output from the source of the first switch tube, and the signal is called the second mixing signal. The intermediate frequency signal / baseband signal reflected back to the first switch tube and the second mixing signal together constitute the third signal.

[0115] In another possible implementation, the first signal is a square wave signal, the second signal is first mixed with the square wave signal of the negative half cycle, and the second signal passed through the first filter and reflected by the reflection circuit is then mixed with the square wave signal of the positive half cycle. The embodiment of the present application does not limit the mixing order of the second signal with the positive half-cycle square wave signal and the negative half-cycle square wave signal.

[0116] The above scheme achieves the effect of reflective mixing by reflecting the second signal back to the first switch tube and mixing it with the first signal again, thereby reducing signal feedthrough and frequency conversion loss. In addition, by adjusting the parameters of the first filter, the filtering delay of the first filter on the signal is adjusted, so that when the second signal enters the first switch tube for mixing again, the first signal is in another half cycle, which reduces the fluctuation in the filter signal band and also reduces the frequency conversion loss.

[0117] In a possible implementation, the first switch tube is a III-V compound switch tube, including but not limited to the following types of switch tubes, for example: gallium arsenide (GaAs) switch tube, gallium arsenide phosphide (GaAsP) switch tube, indium phosphide (InP) switch tube, gallium aluminum arsenide (GaAIAs) switch tube and indium gallium phosphide (InGaP) switch tube, etc. The use of III-V compound switch tubes can improve the linearity of the mixer circuit.

[0118] exist Fig. 7ABased on the mixing circuit shown in FIG. 1 , the embodiment of the present application further provides a schematic diagram of another mixing circuit, such as Figure 7B shown.

[0119] Figure 7B The mixing circuit shown includes: a first switch tube, a first filter, a first resistor, a first circulator and a second filter, wherein the first resistor, the first circulator and the second filter are all optional.

[0120] Figure 7B The connection relationship of the components in the mixing circuit shown is that the first end of the first circulator is connected to the source of the first switch tube, the second end of the first circulator is used to input the second signal, and the third end of the first circulator is used to output the third signal. The gate of the first switch tube is connected to the first end of the second filter, and the second end of the second filter is used to input the first signal. The drain of the first switch tube is connected to the first end of the first filter, the second end of the first filter is connected to the first resistor, and the other end of the first resistor is grounded.

[0121] Exemplarily, the direction of signal flow in the first circulator is that the signal entering from the first end of the first circulator will be output from the third end of the first circulator, the signal entering from the third end of the first circulator will be output from the second end of the first circulator, and the signal entering from the second end of the first circulator will be output from the first end of the first circulator. Therefore, the second signal input from the second end of the first circulator can only be output from the first end of the first circulator, and mixed with the first signal through the first switching device. Similarly, the signal flowing into the first end of the first circulator can only be output from the third end of the first circulator, so that the third signal obtained after mixing the first signal and the second signal can only be output from the third end of the first circulator. Therefore, in Fig. 7A Adding a first circulator on the basis of can reduce the leakage of the second signal or the third signal to other ports, increase the isolation between the ports, and reduce the frequency conversion loss.

[0122] Exemplarily, the first resistor is a large resistor greater than 2K ohms, which is used to form a reflection circuit so that the signal passing through the first filter is reflected back to the first switching device for re-mixing, thereby reducing the frequency conversion loss caused by signal feedthrough.

[0123] Exemplarily, the second filter is a bandpass filter, which is used to select the frequency of the first signal, filter out the signal of the interference frequency band included in the first signal, and reduce the in-band fluctuation. The second filter can also reflect the mixed signal, so that the energy of the signal is concentrated near the switch tube, reducing the loss of the signal energy after mixing.

[0124] In one possible implementation, Figure 7B The first circulator, the first resistor and the second filter are all optional devices. Fig. 7AOn the basis of the invention, adding any one of the first circulator, the first resistor and the second filter has corresponding beneficial effects. Please refer to the above-mentioned related content and no further details will be given here.

[0125] To facilitate readers’ better understanding Fig. 7A and Figure 7B The scheme shown in the present application embodiment is Figure 7B As an example, the signal is shown in Figure 7B The flow process in the mixing circuit shown.

[0126] For example, see Figure 7B . First, as indicated by the arrow numbered "1", the first signal flows to the gate of the first switch tube through the second filter, and as indicated by the arrow numbered "2", the second signal flows to the source of the first switch tube through the first ring device. Secondly, the first signal and the second signal are mixed by the first switch tube, and the first mixed signal is output from the drain of the first switch tube. As indicated by the arrow numbered "3", the signal component of the first mixed signal that cannot pass through the first filter is reflected back to the first switch tube by the first filter and output from the third end of the first circulator. As indicated by the arrow numbered "4", the signal component of the first mixed signal that can pass through the first filter is reflected by the first resistor, enters the first switch tube from the drain of the first switch tube, and is mixed with the first signal. The second mixed signal obtained after mixing is output from the source of the first switch tube, and then input to the first end of the first circulator, and finally output from the third end of the first circulator. As indicated by the arrow numbered "5", the signal output from the third end of the first circulator contains the signal component of the first mixed signal that cannot pass through the first filter and the second mixed signal.

[0127] Above Fig. 7A and Figure 7B The scheme shown, on the one hand, realizes the mixing of the first signal and the second signal by controlling the opening and closing of the switch tube by the first signal, which expands the power dynamic range of the mixer compared to the method of realizing mixing through the channel resistance of the switch tube. On the other hand, by using the drain of the switch tube as the transmitting end, the signal is reflected and mixed again by adding a large resistor, which can reduce the frequency conversion loss of the mixer. By adding a specific filter, the delay of the signal is adjusted so that when the signal enters the first switch tube again, the first signal is a square wave signal of a different half cycle, which can also reduce the frequency conversion loss. In addition, the filter can also filter out the higher harmonics obtained after mixing and reduce the in-band fluctuation of the signal.

[0128] Figure 7B The solution shown can also add a circulator, and the large bandwidth and high isolation characteristics of the circulator can expand the operating frequency range of the mixing circuit.

[0129] In order to support both up-conversion and down-conversion functions, the present application also provides Figure 8 and Fig.10 The mixing circuit shown.

[0130] See also Figure 8 , is a schematic diagram of another mixing circuit provided in an embodiment of the present application. Figure 8 The mixing circuit shown includes: a first circulator, a first switch tube, a first filter, a first resistor, a second filter, a second circulator, a second switch tube, a third filter, a second resistor and a fourth filter, etc. Among them, the first resistor, the second resistor, the second filter and the fourth filter are all optional devices.

[0131] Figure 8 The connection relationship of the components in the mixing circuit shown is that the first end of the first circulator is connected to the source of the first switch tube, the gate of the first switch tube is connected to the first end of the second filter, the second end of the second filter is used to input the first signal, the drain of the first switch tube is connected to the first end of the first filter, the second end of the first filter is connected to the first end of the first resistor, and the second end of the first resistor is grounded. The second end of the first circulator is used to input the second signal, the third end of the first circulator is connected to the first end of the second circulator, the second end of the second circulator is used to output the third signal, the third end of the second signal is connected to the source of the second switch tube, the gate of the second switch tube is connected to the first end of the fourth filter, the second end of the fourth filter is used to input the fourth signal, the drain of the second switch tube is connected to the first end of the third filter, the second end of the third filter is connected to the first end of the second resistor, and the second end of the second resistor is used to ground.

[0132] The flow direction of the signal in the first circulator is that the signal entering from the first end of the first circulator can only be output from the third end of the first circulator, the signal entering from the third end of the first circulator can only be output from the second end of the first circulator, and the signal entering from the second end of the first circulator can only be output from the first end of the first circulator. The flow direction of the signal in the second circulator is that the signal entering from the first end of the second circulator can only be output from the second end of the second circulator, the signal entering from the second end of the second circulator can only be output from the third end of the second circulator, and the signal entering from the third end of the second circulator can only be output from the first end of the second circulator.

[0133] In one possible implementation, the third filter is a high-pass filter and the fourth filter is a band-pass filter. The third filter is used to pass the fifth signal and adjust the delay of the fifth signal so that the reflected fifth signal is mixed again through the second switch tube. The fourth filter is used to select the frequency of the fourth signal, filter out the signal of the interference frequency band included in the fourth signal, and reduce the in-band fluctuation. The fourth filter can also reflect the mixed signal so that the energy of the signal is concentrated near the second switch tube, reducing the loss of signal energy after mixing.

[0134] In a possible implementation, the fourth signal and the first signal may be completely the same signal or different signals. The fourth signal and the first signal may be output from the same local oscillator or different local oscillators. This embodiment of the present application does not limit this.

[0135] In one possible implementation, the first signal is input from the second end of the second filter, the second signal is input from the second end of the first circulator, and the third signal obtained by mixing the first signal and the second signal is output from the second end of the second circulator. For a specific implementation of mixing the first signal and the second signal to generate the third signal, please refer to the above Fig. 7A and Figure 7B The description corresponding to the mixing circuit shown will not be repeated here. Figure 8 The third signal generated by the mixing circuit shown is first output from the third terminal of the first circulator, and then input to the first terminal of the second circulator, and finally output from the second terminal of the second circulator. It can be understood that Figure 8 The mixing circuit shown mixes the first signal and the second signal to generate a third signal without requiring the third filter, the fourth filter, the second switch tube and the second resistor to work.

[0136] In another possible implementation, a fourth signal is input from the second end of the fourth filter, a fifth signal is input from the second end of the second circulator, and a sixth signal obtained by mixing the fourth signal and the fifth signal is output from the second end of the first circulator. In addition, the fifth signal is a radio frequency signal, and the sixth signal is an intermediate frequency signal or a baseband signal.

[0137] Exemplarily, the fifth signal input from the second end of the second circulator can be output from the third end of the second circulator to the source of the second switch tube. The fourth signal input from the fourth filter is filtered and input to the gate of the second circulator. The fourth signal controls the on and off of the second circulator to achieve mixing of the fourth signal and the fifth signal. The fourth signal is a square wave signal including a positive half cycle and a negative half cycle, and the amplitudes of the positive half cycle square wave signal and the negative half cycle square wave signal are equal. From the above Fig. 7AIt can be learned from the introduction that in the process of one mixing, only the mixing of the fifth signal with the positive half-cycle square wave signal or the negative half-cycle square wave signal can be completed. Here, illustratively, the fifth signal is first mixed with the positive half-cycle square wave signal for introduction. The fifth signal is mixed with the positive half-cycle square wave signal, and the mixed signal is output from the drain of the second switch tube, which is called the third mixing signal. The third filter is used to block the intermediate frequency signal or baseband signal through the signal component with a frequency close to the fifth signal in the third mixing signal. Therefore, the intermediate frequency signal or baseband signal in the third mixing signal will be reflected by the third filter, flow through the second switch tube, the third end of the second circulator, the first end of the second circulator and the third end of the first circulator, and finally output from the second end of the first circulator. The signal passing through the third filter will be reflected back to the third filter by the second resistor, and mixed through the second switch tube and the negative half-cycle signal of the fourth signal. The mixed signal obtained after mixing is called the fourth mixing signal. The fourth mixing signal is output from the source of the second switch tube, flows through the second switch tube, the third end of the second circulator, the first end of the second circulator and the third end of the first circulator, and is finally output from the second end of the first circulator. The intermediate frequency signal or baseband signal in the third mixing signal and the fourth mixing signal form a sixth signal.

[0138] Exemplarily, the second resistor is a large resistor greater than 2K ohms, which is used to form a reflection circuit so that the signal passing through the third filter is reflected back to the second switching device for re-mixing, thereby reducing the frequency conversion loss caused by signal feedthrough.

[0139] In a possible implementation, the second switch tube is a III-V compound switch tube, including but not limited to the following types of switch tubes, for example: gallium arsenide (GaAs) switch tube, gallium arsenide phosphide (GaAsP) switch tube, indium phosphide (InP) switch tube, gallium aluminum arsenide (GaAIAs) switch tube and indium gallium phosphide (InGaP) switch tube, etc. The use of III-V compound switch tubes can improve the linearity of the mixer circuit.

[0140] In another possible implementation, a fourth signal is input from the second end of the fourth filter, a fifth signal is input from the second end of the second circulator, and a sixth signal obtained by mixing the fourth signal and the fifth signal is output from the second end of the first circulator. In addition, the fifth signal is an intermediate frequency signal or a baseband signal, and the sixth signal is a radio frequency signal. For the specific implementation of this solution, please refer to the above-mentioned related description, which will not be repeated here.

[0141] Understandably, Figure 8 The mixing circuit shown mixes the fourth signal and the fifth signal to generate the sixth signal without requiring the first filter, the second filter, the first switch tube and the first resistor to work.

[0142] In a possible implementation, the second signal and the sixth signal are intermediate frequency signals or baseband signals, and the third signal and the fifth signal are radio frequency signals. This solution can achieve up-conversion of the second signal and down-conversion of the fifth signal.

[0143] In another possible implementation, the second signal and the sixth signal are radio frequency signals, and the third signal and the fifth signal are intermediate frequency signals or baseband signals. This solution can down-convert the second signal and up-convert the fifth signal.

[0144] In one possible implementation, Figure 8 The RF circuit shown also includes a fifth filter and / or a sixth filter. The first end of the fifth filter is connected to the second end of the first circulator, and the second end of the fifth filter is used to receive the second signal or send the sixth signal. The first end of the sixth filter is connected to the second end of the second circulator, and the second end of the sixth filter is used to send the third signal or receive the fifth signal.

[0145] The fifth filter and the sixth filter are both used to filter the passing signal to reduce useless signals or high-order harmonics in the signal. Figure 8 The mixing circuit shown is used to up-convert the second signal, and the generated third signal is sent out from the second end of the second circulator. From the above analysis, it can be known that the third signal sent out from the second end of the second circulator contains a large number of high-order harmonics. Therefore, adding a sixth filter at the second end of the second circulator can reduce the number of high-order harmonics in the third signal.

[0146] Similarly, the sixth filter can also filter the received fifth signal. The functions implemented by the fifth filter and the sixth filter are similar. For the function of the fifth filter, please refer to the above description of the sixth filter, which will not be repeated here.

[0147] Exemplarily, the fifth filter and the sixth filter are both bandpass filters.

[0148] Next, the present application embodiment is Fig. 9A and Fig. 9B It is shown as an example Figure 8 Related experimental results of the mixing circuit shown.

[0149] Please see first Fig. 9A , Fig. 9A A schematic diagram of up-conversion loss provided in an embodiment of the present application. Fig. 9A It is shown as an example Figure 8 The conversion loss at various operating frequencies and various input powers when the mixer circuit is performing up-conversion.

[0150] like Fig. 9A As shown, Fig. 9A The vertical axis is used to represent the frequency conversion loss in dB. Fig. 9A The horizontal axis is used to represent the operating frequency in GHz. Fig. 9A The operating frequency ranges from 0.985 GHz to 1.185 GHz. Fig. 9A The legend is used to indicate the input power in dBm. Fig. 9A Medium input powers include 13dBm, 16dBm, 19dBm, 22dBm and 25dBm.

[0151] from Fig. 9A It can be seen from the figure that the relationship between the operating frequency and the frequency conversion loss is that when the operating frequency increases from 0.985 GHz to 1.115 GHz, the frequency conversion loss decreases. When the operating frequency increases from 1.115 GHz to 1.185 GHz, the frequency conversion loss increases.

[0152] The relationship between input power and frequency conversion loss is that as the input power increases, the frequency conversion loss shows an overall increasing trend. Among them, when the input power is between 13dBm and 22dBm, there is no obvious pattern between the frequency conversion loss and the input power. However, when the input power is 25dBm, the frequency conversion loss increases significantly. Taking the input power of 22dBm and 25dBm as an example, at the same frequency, the input power of 25dBm is about 0.8dB higher than the input power of 22dBm. Fig. 9A It can be seen that when the input power is 22dBm and the operating frequency is 1.135GHz, the maximum value of the frequency conversion loss is 7.7dB.

[0153] See also Fig. 9B , Fig. 9B A schematic diagram of the relationship between OIP3 and operating frequency provided in an embodiment of the present application. Fig. 9B As shown in the figure, the horizontal axis is used to represent the operating frequency in GHz. The vertical axis is used to represent OIP3 in dBm. When the operating frequency is 0.985 GHz, the OIP3 is 31 dBm. Fig. 9A It can be seen that Figure 8 The minimum conversion loss of the mixer shown is about 6dB, so, Figure 8 The IIP3 of the mixer shown will be greater than 37dBm.

[0154] Figure 8The mixer circuit shown, firstly, uses the switch tube of the III-V group process as the key device to realize the mixing function, which can make the mixer circuit achieve the goal of high linearity. Secondly, by using a circulator and utilizing the high isolation characteristics of the circulator to separate the intermediate frequency signal and the radio frequency signal, the frequency conversion loss and in-band fluctuation of the mixer circuit can be reduced. Thirdly, by adding a large resistor or grounding to the drain of the switch tube to realize the reflection circuit, the frequency conversion loss caused by signal feedthrough can be reduced, and the goal of low loss of the mixer circuit can be achieved. Finally, by adding a suitable filter to the drain of the switch tube, the filtering delay of the signal can be adjusted so that the reflected signal can be mixed with the square wave signal of the other half cycle, further reducing the frequency conversion loss. In addition, the filter can also filter out interference signals and reduce in-band fluctuations.

[0155] Fig.10 A schematic diagram of another frequency mixing circuit provided in an embodiment of the present application is shown below. Fig.10 Another mixing circuit shown is introduced as an example.

[0156] Fig.10 The mixing circuit shown includes a first filter, a second filter, a fifth filter, a sixth filter, a first switch tube, a first resistor, etc. Among them, the second filter and the first resistor are optional devices.

[0157] Fig.10 The connection relationship of the components in the mixing circuit shown is that the first end of the fifth filter is connected to the source of the first switch tube, and the second end of the fifth filter is used to input the second signal. The gate of the first switch tube is connected to the first end of the second filter, and the second end of the second filter is used to input the first signal. The drain of the first switch tube is connected to the first end of the first filter, the second end of the first filter is connected to the first end of the first resistor, and the second end of the first resistor is grounded. The source of the first switch tube is also connected to the first end of the sixth filter, and the second end of the sixth filter is used to output the third signal.

[0158] Fig.10 The mixer circuit shown is compared to Fig. 7A The mixing circuit shown has a fifth filter and a sixth filter added thereto. Fig.10 For a specific implementation of the mixing circuit shown in FIG. 1 mixing the first signal and the second signal to generate the third signal, please refer to the aforementioned Fig. 7A The relevant description will not be repeated here.

[0159] In a possible implementation, the sixth filter is used to filter the third signal obtained by mixing the first signal and the second signal to reduce the higher harmonics in the third signal. The fifth filter is used to filter the second signal to reduce the interference signal in the second signal.

[0160] Exemplarily, when the second signal is an intermediate frequency signal or a baseband signal, the fifth filter is a bandpass filter, the fifth filter filters the input second signal, the second filter filters the input first signal, and the signals filtered by the fifth filter and the second filter are respectively input to the source and drain of the first switch tube, which can filter out useless signals in the first signal and the second signal and reduce the in-band fluctuation of the mixed signal. The sixth filter is a bandpass filter, which is used to pass the radio frequency signal (the frequency of the radio frequency signal is equal to the sum of the frequencies of the first signal and the second signal) to reduce the interference of other high-order harmonics on the signal.

[0161] Exemplarily, when the second signal is a radio frequency signal, the fifth filter is a bandpass filter, the fifth filter filters the input second signal, the second filter filters the input first signal, and the signals filtered by the fifth filter and the second filter are respectively input to the source and drain of the first switch tube, which can filter out useless signals in the first signal and the second signal and reduce the in-band fluctuation of the mixed signal. The sixth filter is a bandpass filter, which is used to reduce the interference of other high-order harmonics on the signal through an intermediate frequency signal or a baseband signal (the frequency of the intermediate frequency signal or the baseband signal is equal to the difference between the frequencies of the first signal and the second signal).

[0162] Next, the present application embodiment is Fig.11A , Fig. 11B and Fig. 11C It is shown as an example Fig.10 Related experimental results of the mixing circuit shown.

[0163] Please see first Fig.11A , Fig.11A A schematic diagram of another up-conversion loss provided in an embodiment of the present application. Fig.11A It is shown as an example Fig.10 The conversion loss at various operating frequencies and various input powers when the mixer circuit is performing up-conversion.

[0164] like Fig.11A As shown, Fig.11A The vertical axis is used to represent the frequency conversion loss in dB. Fig.11A The horizontal axis is used to represent the operating frequency in GHz. Fig.11A The operating frequency ranges from 0.985 GHz to 1.185 GHz. Fig.11A The legend is used to indicate the input power in dBm. Fig. 9A Medium input powers include 13dBm, 16dBm, 19dBm, 22dBm and 25dBm.

[0165] from Fig.11AIt can be seen from the figure that the relationship between the operating frequency and the frequency conversion loss is that the frequency conversion loss shows a random oscillation change as the operating frequency increases. For example, when the operating frequency is between 0.985GHz and 0.995GHz, the frequency conversion loss decreases as the operating frequency increases. When the operating frequency is between 0.995GHz and 1.045GHz, the frequency conversion loss increases as the operating frequency increases. When the operating frequency is between 1.045GHz and 1.175GHz, the frequency conversion loss decreases as the operating frequency increases. When the operating frequency is between 1.175GHz and 1.185GHz, the frequency conversion loss increases as the operating frequency increases.

[0166] In addition, from Fig.11A It can be seen that the input power has little effect on the conversion loss. For example, when the operating frequency is 1.085GHz, the conversion loss of the input power of 13dBm and the input power of 22dBm are both about 5dB. However, at some operating frequencies, the conversion loss will increase with the increase of input power. For example, when the operating frequency is 1.155GHz, the conversion loss of the input power of 22dBm is about 5dB, and the conversion loss of the input power of 13dBm is about 4dB. Fig.11A The maximum down-conversion loss shown is around 6dB.

[0167] See also Fig. 11B , Fig. 11B A schematic diagram of down-conversion loss provided in an embodiment of the present application. Fig. 11B It is shown as an example Fig.10 Conversion loss at various operating frequencies and input powers when the mixer circuit is down-converting.

[0168] like Fig. 11B As shown, Fig. 11B The vertical axis is used to represent the frequency conversion loss in dB. Fig. 11B The horizontal axis is used to represent the operating frequency in GHz. Fig. 11B The operating frequency range is from 3.4GHz to 3.6GHz. Fig. 11B The legend is used to indicate the input power in dBm. Fig. 11B Medium input powers include 13dBm, 16dBm, 19dBm, 22dBm and 25dBm.

[0169] from Fig. 11BIt can be seen from the figure that the relationship between the operating frequency and the conversion loss is that when the operating frequency increases from 3.4GHz to 3.6GHz, the overall conversion loss increases with the increase of the operating frequency. However, there is also a local decrease in the conversion loss as the operating frequency increases. For example, from 3.45GHz to 3.5GHz, the overall conversion loss decreases as the operating frequency increases. In addition, when the input power is 13dBm, the overall conversion loss decreases as the operating frequency increases.

[0170] The relationship between input power and frequency conversion loss is that when the operating frequency is between 3.4GHz and 3.5GHz, there is a negative correlation between input power and frequency conversion loss. The greater the input power, the smaller the frequency conversion loss. When the operating frequency is between 3.5GHz and 3.6GHz, there is a positive correlation between input power and frequency conversion loss. The greater the input power, the greater the frequency conversion loss. Fig. 11B It can be seen that when the input power is 25dBm and the operating frequency is 3.6GHz, the maximum value of the frequency conversion loss is about 8dB.

[0171] See also Fig. 11C , Fig. 11C Another schematic diagram of the relationship between OIP3 and operating frequency provided in an embodiment of the present application. Fig. 11C As shown in the figure, the horizontal axis is used to represent the operating frequency in GHz. The vertical axis is used to represent OIP3 in dBm. When the operating frequency is 0.985 GHz, the OIP3 is about 30.18 dBm. Fig. 11C It can be seen that Fig.10 The minimum conversion loss of the mixer shown is about 4dB, so, Fig.10 The IIP3 of the mixer shown will be greater than 34dBm. Fig.10 When the mixer operates at 1.085 GHz, the conversion loss is about 5 dB and O1P3 is greater than 31 dB. Fig.10 The IIP3 of the mixer shown is greater than 36dBm when operating at a frequency of 1.085GHz.

[0172] Fig.10The mixer circuit shown, firstly, uses the switch tube of the III-V group process as the key device to realize the mixing function, which can make the mixer circuit achieve the goal of high linearity. Secondly, adding a large resistor or grounding to the drain of the switch tube to realize the reflection circuit can reduce the frequency conversion loss caused by signal feedthrough, and achieve the goal of low loss of the mixer circuit. Finally, by adding a suitable filter to the drain of the switch tube, the filtering delay of the signal can be adjusted so that the reflected signal can be mixed with the square wave signal of the other half cycle, further reducing the frequency conversion loss. In addition, the filter can also filter out interference signals and reduce in-band fluctuations.

[0173] In one possible implementation, the above Figure 8 and Fig.10 The mixing circuit shown can be reused with filters in the existing network, which can significantly reduce the networking cost.

[0174] For example, if a filter for filtering the local oscillator signal already exists in the existing network, then Fig.10 The second filter in the mixing circuit shown can use the filter already existing in the existing network, thereby reducing the networking cost.

[0175] For example, if there is already a filter in the existing network for filtering the intermediate frequency signal or the baseband signal, then Fig.10 The fifth filter in the mixing circuit shown can use the filter already existing in the existing network, thereby reducing the networking cost.

[0176] For example, if a filter for filtering radio frequency signals already exists in the existing network, then Fig.10 The sixth filter in the mixing circuit shown can use the filter already existing in the existing network, thereby reducing the networking cost.

[0177] Likewise, Figure 8 The second filter, the fourth filter, the fifth filter and the sixth filter in the mixer circuit shown can also be shared with filters already existing in the line network.

[0178] The present application also provides a circuit board, which includes the above-mentioned Fig. 7A , Figure 7B , Figure 8 or Fig.10 And a mixing circuit in possible embodiments thereof.

[0179] The present application also provides a mixer, which includes the above-mentioned Fig. 7A , Figure 7B , Figure 8 or Fig.10 And a mixing circuit in possible embodiments thereof.

[0180] The present application also provides a communication device, which includes the above-mentioned Fig. 7A , Figure 7B , Figure 8 or Fig.10 And a mixing circuit in possible embodiments thereof.

[0181] In this application, the terms "first", "second", etc. are used to distinguish between identical or similar items with substantially the same effects and functions. It should be understood that there is no logical or temporal dependency between "first", "second", and "nth", nor is there a limitation on the quantity and execution order. It should also be understood that although the following description uses the terms first, second, etc. to describe various elements, these elements should not be limited by the terms. These terms are only used to distinguish one element from another element.

[0182] It should also be understood that in the various embodiments of the present application, the size of the serial number of each process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0183] It should also be understood that the term “comprise” (also known as “includes,” “including,” “comprises” and / or “comprising”) when used in this specification specifies the presence of stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0184] It should also be understood that the references to "one embodiment", "an embodiment", or "a possible implementation" throughout the specification mean that specific features, structures, or characteristics related to the embodiment or implementation are included in at least one embodiment of the present application. Therefore, the references to "in one embodiment" or "in an embodiment", or "a possible implementation" throughout the specification do not necessarily refer to the same embodiment. In addition, these specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0185] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A mixing circuit, characterized in that: The mixing circuit includes a first switch tube and a first filter; The gate of the first switch tube is used to input a first signal, and the first signal is used to control the on and off of the first switch tube; The drain of the first switch tube is used to be connected to the first end of the first filter, and the second end of the first filter is used to be grounded; The source of the first switch tube is used to input a second signal, and the source of the first switch tube is also used to output a third signal, where the third signal is a signal obtained by mixing the first signal and the second signal.

2. The mixer circuit according to claim 1, characterized in that: The frequency mixing circuit further includes a first resistor; The second end of the first filter is specifically used to be connected to the first end of the first resistor, and the second end of the first resistor is used to be grounded.

3. The mixer circuit according to claim 1 or 2, characterized in that: The mixing circuit further includes a second filter; the gate of the first switch tube is used to input a first signal, including: The gate of the first switch tube is used to be connected to the first end of the second filter, and the second end of the second filter is used to input the first signal.

4. The mixer circuit according to any one of claims 1 to 3, characterized in that: The mixing circuit also includes a first circulator; The source of the first switch tube is specifically used to connect to the first end of the first circulator; the second end of the first circulator is used to input the second signal, and the third end of the first circulator is used to output the third signal.

5. The mixer circuit according to claim 4, characterized in that: The mixing circuit also includes a second circulator, a second switch tube and a third filter; The third end of the first circulator is used to output the third signal, including: The third end of the first circulator is used to connect to the first end of the second circulator, and the second end of the second circulator is used to output the third signal; The third end of the second circulator is used to connect the source of the second switch tube; the gate of the second switch tube is used to input a fourth signal, and the fourth signal is used to control the on and off of the second switch tube to achieve mixing of the fourth signal and a fifth signal, and the fifth signal is input from the second end of the second circulator; the output time of the third signal is different from the input time of the fifth signal; The drain of the second switch tube is used to be connected to the first end of the third filter, and the second end of the third filter is used to be grounded.

6. The mixer circuit according to claim 4 or 5, characterized in that: The mixing circuit further includes a second resistor; The second end of the third filter is specifically used to be connected to the first end of the second resistor, and the second end of the second resistor is used to be grounded.

7. The mixer circuit according to any one of claims 4 to 6, characterized in that: The mixing circuit further includes a fourth filter; the gate of the second switch tube is used to input a fourth signal, including: The gate of the second switch tube is used to be connected to the first end of the fourth filter, and the second end of the fourth filter is used to input the fourth signal.

8. The mixer circuit according to any one of claims 4 to 7, characterized in that: The mixing circuit further includes a fifth filter; the second end of the first circulator is used to input the second signal, including: The second end of the first circulator is specifically used to connect to the first end of the fifth filter, and the second end of the fifth filter is used to input the second signal.

9. The mixer circuit according to any one of claims 5 to 8, characterized in that: The mixing circuit further includes a sixth filter; the second end of the second circulator is used to output the third signal, including: The second end of the second circulator is specifically used to connect to the first end of the sixth filter, and the second end of the sixth filter is used to output the third signal.

10. The mixer circuit according to any one of claims 1 to 3, characterized in that: The mixing circuit further includes a fifth filter; the source of the first switch tube is used to input a second signal, including: The source of the first switch tube is specifically used to be connected to the first end of the fifth filter, and the second end of the fifth filter is used to input the second signal.

11. The mixer circuit according to any one of claims 1 to 3 and 10, characterized in that: The mixing circuit further includes a sixth filter; the source of the first switch tube is also used to output a third signal, including: The source of the first switch tube is specifically used to be connected to the first end of the sixth filter, and the second end of the sixth filter is used to output the third signal.

12. The mixer circuit according to any one of claims 1 to 11, characterized in that: The first signal is a local oscillator signal, the second signal is a baseband signal or an intermediate frequency signal, and the third signal is a radio frequency signal; The mixing circuit is used to up-convert the second signal to obtain the third signal.

13. The mixer circuit according to any one of claims 1, 2, 3, 10 and 11, characterized in that: The first signal is a local oscillator signal, the second signal is a radio frequency signal, and the third signal is a baseband signal or an intermediate frequency signal; The frequency mixing circuit is used to down-convert the second signal to obtain the second signal.

14. A circuit board, characterized in that: The circuit board comprises the mixing circuit according to any one of claims 1-13.

15. A mixer, characterized in that: The mixer comprises the mixing circuit according to any one of claims 1 to 13.

16. A communication device, characterized in that: The device comprises a processor and the mixing circuit according to any one of claims 1 to 13.

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