Radio frequency circuit, wireless communication device and method of operating radio frequency circuit

Abstract

Disclosed are a radio frequency circuit, a wireless communication device, and a method of operating a radio frequency circuit, the radio frequency circuit including: a mixer converting a first signal to a second signal using a local oscillator (LO) signal; the amplifier is used for amplifying the second signal; and an impedance tuner circuit connected between the mixer and the input terminal of the amplifier and configured to adjust the conversion gain of the mixer by presenting a variable impedance.

Description

[0001] This application claims the priority of Korean Patent Application No. 10-2023-0090688 filed on July 12, 2023, in the Korean Intellectual Property Office, and Korean Patent Application No. 10-2023-0142678 filed on October 24, 2023, in the Korean Intellectual Property Office, respectively, the disclosures of which are incorporated herein by reference in their entirety. Technical Field

[0002] Embodiments of the present disclosure described herein relate to radio frequency (RF) circuits and methods of operating radio frequency (RF) circuits. Background Art

[0003] Various dynamic ranges may be required for an RF transmission chain (Tx chain). For example, a communication protocol such as the 3rd Generation Partnership Project (3GPP) may require a dynamic range of about 80 dB or more for a cellular transmission chain. If so, each of several blocks included in the transmission chain may be designed to ensure the required dynamic range through gain control.

[0004] At the same time, a circuit structure with a wider gain control range and a structure for performance optimization may be in a trade-off relationship. Therefore, in order to extend the gain control range of the entire transmission chain without reducing the performance of each block included in the transmission chain, it may be necessary to optimize the performance of each block and at the same time design the blocks to share the load of gain control with each other. Summary of the invention

[0005] Embodiments of the present disclosure provide an RF circuit and a method of operating the RF circuit capable of controlling the conversion gain of a mixer. The conversion gain control of various embodiments can result in an extended gain control range of the RF circuit.

[0006] According to an embodiment of the present disclosure, an RF circuit includes: a mixer that converts a first signal into a second signal using a local oscillator (LO) signal; an amplifier that amplifies the second signal; and an impedance tuner circuit that is connected between the mixer and an input terminal of the amplifier and is configured to adjust a conversion gain of the mixer by presenting a variable impedance.

[0007] According to an embodiment of the present disclosure, a wireless communication device includes: an RF integrated circuit (RFIC) that up-converts a baseband signal to output an RF signal, and a power amplifier that amplifies the RF signal. The RFIC includes: a mixer that converts the baseband signal into an RF signal using an LO signal; an amplifier that amplifies the RF signal; and an impedance tuner circuit that is connected between the mixer and an input terminal of the amplifier and controls the conversion gain of the mixer by presenting a variable impedance.

[0008] According to an embodiment of the present disclosure, a method of operating an RF circuit includes: adjusting a conversion gain of a mixer by changing an impedance of an impedance tuner circuit; converting a first signal into a second signal using an LO signal applied to the mixer; and amplifying the second signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and other aspects and features of the present disclosure will become apparent by describing in detail embodiments of the present disclosure with reference to the attached drawings.

[0010] Figure 1 A radio frequency (RF) circuit is shown in accordance with some embodiments.

[0011] Figure 2 and Figure 3 According to some embodiments Figure 1 operation of the RF circuits.

[0012] Figure 4 and Figure 5 RF band characteristics according to conversion gain control according to some embodiments are shown.

[0013] Figure 6 The RF circuit is shown when the impedance tuner circuit is disconnected, according to some embodiments.

[0014] Figure 7 and Figure 8 The RF circuit is shown when the impedance tuner circuit is turned on, according to some embodiments.

[0015] Fig. 9 The relationship between load impedance and conversion gain according to some embodiments is shown.

[0016] Fig.10 The relationship between the gain index and the output of an amplifier according to some embodiments is shown.

[0017] Fig.11 A layout of an RF circuit according to some embodiments is shown.

[0018] Fig.12 is a flow chart illustrating a method of operating an RF circuit according to some embodiments.

[0019] Fig.13 is a flow chart illustrating a method for adjusting the impedance of an RF circuit according to some embodiments.

[0020] Fig.14 A wireless communication apparatus is shown in accordance with some embodiments.

[0021] Fig.15 An IoT (Internet of Things) device to which a wireless communication device is applied according to some embodiments is shown.

[0022] Fig.16 A mobile terminal to which a wireless communication device is applied according to some embodiments is shown. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present disclosure will be described in detail and clearly to the extent that a person having ordinary skill in the art can easily implement the embodiments of the present disclosure.

[0024] Figure 1 A radio frequency (RF) circuit is shown in accordance with some embodiments.

[0025] Reference Figure 1 , the RF circuit 100 may include a mixer 110, an impedance tuner circuit (ITC) 120, and an amplifier 140. According to some embodiments, a matching network (eg, a tunable matching network) 130 may be additionally included.

[0026] The mixer 110 may be configured to convert the first signal S1 into the second signal S2 using a local oscillator (LO) signal applied to the mixer 110. The LO signal LO may be provided by an oscillator (not shown) and may have a frequency for up-converting the frequency of the first signal S1 into the frequency of the second signal S2 in a higher frequency band. The mixer 110 may up-convert the first signal S1 into the second signal S2 in a higher frequency band by mixing the first signal S1 and the LO signal LO. For example, the first signal S1 may be a baseband signal having a baseband frequency, and the second signal S2 may be an RF signal having an RF frequency.

[0027] According to some embodiments, the mixer 110 may be implemented as an active mixer using a direct current (DC) power supply or a passive mixer not using a DC input. The mixer 110 may be implemented as a differential mixer or a single-ended mixer. The mixer 110 may be implemented by using various circuit elements including nonlinear elements such as transistors.

[0028] The mixer 110 may have a conversion gain. Therefore, the second signal S2 as the output of the mixer 110 may have a power that increases the conversion gain from the first signal S1. For example, the conversion gain of the mixer 110 may be determined based on the "on resistance" of the transistors included in the mixer 110 and the voltage distribution according to the load impedance ZL of the mixer 110. When the load impedance ZL of the mixer 110 has a fixed value (as in a conventional RF circuit), it may be difficult to adjust the conversion gain.

[0029] The impedance tuner circuit 120 may be connected between the mixer 110 and the input terminal of the amplifier 140. The impedance tuner circuit 120 may be configured so that its own impedance can be changed. For example, the impedance tuner circuit 120 may have a variable impedance VZ connected between a first transmission line conductor tc1 and a second transmission line conductor tc2, which may be transmission lines or interconnected conductors through which the second signal S2 is output from the mixer 110. The variable impedance VZ may be presented to the output of the mixer 110 so that the load impedance ZL of the mixer is based on a combination of the transmission line or interconnect impedance, the impedance VZ, and the impedance "looking into" the matching network 130. According to some embodiments, the variable impedance VZ of the impedance tuner circuit 120 may be implemented based on passive elements (such as switchable resistors, capacitors, and inductors) so that the variable impedance VZ is suitable for various matching networks 130. Additionally, the impedance tuner circuit 120 may be implemented to include one or more variable impedance circuits, each variable impedance circuit including one or more passive elements.

[0030] By changing the impedance VZ, the impedance tuner circuit 120 can adjust the conversion gain of the mixer 110. For this reason, when the impedance VZ of the impedance tuner circuit 120 changes, the load impedance ZL of the mixer 110 may also change. In other words, the impedance tuner circuit 120 can change the load impedance ZL of the mixer 110 by changing the impedance VZ of the impedance tuner circuit 120. Finally, when the load impedance ZL of the mixer 110 changes due to the impedance tuner circuit 120, the conversion gain determined based on the load impedance ZL may also change.

[0031] According to some embodiments, the impedance tuner circuit 120 may be configured to have a variable impedance VZ based on the output power of the RF circuit 100. Here, the impedance tuner circuit 120 may be operated to have a switchable impedance VZ according to the desired output power of the RF circuit 100. For example, when the RF circuit 100 is operated in a high power mode, the impedance tuner circuit 120 may be controlled to be "disconnected" in which the output power of the RF circuit 100 is greater than or equal to a first threshold. In this case, disconnecting the impedance tuner circuit 120 may mean that the impedance VZ of the impedance tuner circuit 120 is theoretically infinite (correspondingly, the admittance of the impedance tuner circuit 120 is "0"). In other words, the impedance tuner circuit 120 appears to be approximately non-existent to the rest of the RF circuit 100. Therefore, the load impedance ZL may be based only on the characteristic impedance of the transmission line or interconnect with the conductors tc1 and tc2 and the combination of the impedance seen by the matching network 130 (if present) or the amplifier 140 (if the matching network 130 is omitted).

[0032] Therefore, when the impedance tuner circuit 120 is disconnected, the load impedance ZL of the mixer 110 will have a maximum value when other impedances included in the load impedance ZL do not change. Therefore, disconnecting the impedance tuner circuit 120 can maximize the conversion gain of the mixer 110.

[0033] Conversely, when the RF circuit 100 operates in a low power mode, in which the output power of the RF circuit 100 is less than or equal to the second threshold, the impedance tuner circuit 120 may be turned on. In this case, turning on the impedance tuner circuit 120 may mean that the impedance VZ of the impedance tuner circuit 120 has a specific value other than infinity.

[0034] When the impedance tuner circuit 120 is turned on, (assuming that other impedances included in the load impedance ZL do not change) the load impedance ZL of the mixer 110 may have a lower impedance value than when the impedance tuner circuit 120 is turned off. When the impedance presented by the impedance tuner circuit 120 is reduced, the load impedance ZL of the mixer 110 will also be reduced. Therefore, when the impedance tuner circuit 120 is turned on and the impedance is reduced, the conversion gain of the mixer 110 will be reduced.

[0035] When the conversion gain is adjusted by the impedance tuner circuit 120, the power of the second signal S2 as the output signal of the mixer 110 will also be changed. When the impedance tuner circuit 120 is disconnected, the conversion gain will be the highest, so the second signal S2 can have a larger power. On the contrary, when the impedance tuner circuit 120 is turned on and the impedance is reduced, the conversion gain will decrease, so the second signal S2 can have a lower power. As will be described later, adjusting the conversion gain of the mixer 110 by the impedance tuner circuit 120 can help reduce the size of the leakage component of the amplifier 140.

[0036] The amplifier 140 may be configured to amplify the second signal S2. For example, the amplifier 140 may be a driving amplifier DA for amplifying the second signal S2 before the power amplifier PA. The amplifier 140 may output the amplified RF signal D_RF by amplifying the second signal S2 based on the amplifier gain (hereinafter, referred to as "signal gain" (to distinguish the gain from the "leakage gain" discussed below)). In order to ensure the dynamic range of the RF circuit 100, the amplifier 140 may have a gain control function. Considering that the gain control is performed on the first signal S1 of the baseband corresponding to the front stage of the amplifier 140, since the front stage of the amplifier 140 has a more direct impact on the signal-to-noise ratio (SNR), it may be difficult to perform wide gain control in a conventional RF circuit. In addition, in a conventional RF circuit, since the leakage amount of the LO signal LO may change during the gain control in the front stage of the amplifier 140, it may be necessary to perform a DC offset cancellation (DCOC) calibration each time the gain control is performed. Therefore, in an embodiment of the present disclosure, the amplifier 140 may allow the RF circuit 100 to have a wider dynamic range by supporting gain control and does not require a separate DCOC calibration.

[0037] In this case, in addition to the second signal S2 as a signal desired to be amplified, the amplifier 140 may also amplify an unwanted leakage component due to a parasitic component (or coupling path) depending on the embodiment of the amplifier 140. Hereinafter, the gain of the leakage component will be referred to as leakage gain, separate from the signal gain of the desired signal. Depending on the design of the amplifier 140, the leakage gain may have a fixed value. For example, even if the input signal to the amplifier 140 or the signal gain of the amplifier 140 changes, the leakage gain may be fixed.

[0038] When the RF circuit 100 operates at a lower output power to ensure the dynamic range, the amplifier 140 may need to provide attenuation rather than gain to the input signal S2 to generate the amplified RF signal D_RF at a lower output power. To this end, in order to reduce the output power of the RF circuit 100, the signal gain of the amplifier 140 may be reduced. In this case, (because the leakage gain may be fixed even when the signal gain is reduced) the influence of the leakage component according to the leakage gain may be relatively increased. When the leakage component becomes the main component relative to the desired signal, the leakage component may serve as a lower limit for the dynamic range.

[0039] According to some embodiments described herein, the impedance tuner circuit 120 may be provided at the output of the mixer 110 to adjust the conversion gain of the mixer 110. When the conversion gain of the mixer 110 is reduced by the impedance tuner circuit 120, the size of the second signal S2 provided to the input terminal of the amplifier 140 may also be reduced. In this case, reducing the conversion gain of the mixer 110 also reduces the leakage component applied to the input of the amplifier 140. Then, the leakage component output by the amplifier 140 having a fixed leakage gain may be relatively reduced. In other words, the amplifier 140 may output a reduced leakage component from the second signal S2 as the conversion gain decreases.

[0040] According to some embodiments, the amplifier 140 may adjust the signal gain through gain control. Specifically, the amplifier 140 may increase the signal gain to compensate for the reduction in conversion gain by the impedance tuner circuit 120. Therefore, the amplifier 140 amplifies the second signal S2 according to the increased amplifier gain, and thus may output an amplified RF signal D_RF having a desired output power despite the reduced conversion gain.

[0041] According to some embodiments, the RF circuit 100 may further include a matching network 130 connected between the impedance tuner circuit 120 and an input terminal of the amplifier 140. The matching network 130 may be configured to provide impedance matching between the mixer 110 and the amplifier 140. For example, the matching network 130 may be implemented based on an LC loop, a transformer, etc.

[0042] According to the embodiments described above, the conversion gain of the mixer 110 can be adjusted by the impedance tuner circuit 120, and thus the gain of the RF circuit 100 can be adjusted. Therefore, according to some embodiments, the matching network 130 may not require a separate gain control function. In this case, the matching network 130 can tune the load impedance ZL to an optimal value so that when the RF circuit 100 operates at a higher gain, the RF circuit 100 can meet the minimum current and maximum output power requirements.

[0043] According to the above-described embodiments, the RF circuit 100 of the present disclosure can adjust the conversion gain of the mixer 110 by changing the load impedance ZL of the mixer 110 via the impedance tuner circuit 120. By adjusting the conversion gain of the mixer 110, the embodiments of the present disclosure can reduce the lower limit of the dynamic range (such as the gain) by relatively reducing the leakage component of the amplifier 140. Fig.10 , discussed later). Therefore, according to the present disclosure, the dynamic range of the RF circuit 100 can be increased.

[0044] Figure 2 and Figure 3 According to some embodiments Figure 1operation of the RF circuits.

[0045] First, refer to Figure 2 The impedance tuner circuit 120 may be disconnected in certain circumstances (such as in the high power mode discussed above). In this case, since the load impedance of the mixer 110 will be fixed, the conversion gain of the mixer 110 will also have a fixed value.

[0046] When the conversion gain of the mixer 110 is not adjusted, and when the mixer 110 is a passive mixer, the second signal S2, which is the output signal of the mixer 110, will also have a fixed power P1. In addition, as described above, the leakage gain G_LE of the amplifier 140 will have a fixed value, resulting in a leakage component LE output from the amplifier 140 with a power P2 (when the conversion gain is at a maximum value, the power P2 may be fixed even when the signal gain is adjusted). Therefore, the amplified RF signal D_RF will have a power P3, which is P1 multiplied by the signal gain G_DA. In this case, as shown, when the leakage component LE finally output by the amplifier 140 is greater than the amplified RF signal D_RF as the desired signal, the leakage component LE becomes the main component and may also serve as a lower limit of the dynamic range. Therefore, the amplified RF signal D_RF may not have the desired (or expected) output power, but may be limited by the power of the leakage component LE during the low power mode. The following is combined with Fig.10 A further explanation of this lower limit is described.

[0047] When the output power required by the RF circuit 100 is reduced, when the signal gain G_DA is less than the leakage gain G_LE, the lower limit problem caused by the leakage component LE described above may occur. In addition, in a conventional RF circuit lacking the impedance tuner circuit 120, the conversion gain of the mixer 110 is adjusted without using a variable output impedance, and the size of the second signal S2 may not be adjusted, so the lower limit problem caused by the leakage component LE may not be solved.

[0048] Next, refer to Figure 3 According to some embodiments, when the impedance tuner circuit 120 is set and turned on, the conversion gain of the mixer 110 may be adjusted. For example, the impedance tuner circuit 120 may reduce the conversion gain of the mixer 110, and thus, the second signal S2 may have a power P4 lower than the power P1. Similarly, when the leakage gain G_LE is the same, the leakage component LE has a power P4 lower than the power P1. Figure 2 Finally, the size of the leakage component LE can be further reduced by conversion gain control.

[0049] In addition, according to some embodiments, the amplifier 140 may further increase the signal gain G_DA to compensate for the reduced power of the second signal S2 by conversion gain control. Figure 2 The same power P3 (or a power level similar to P3) shown in FIG.

[0050] Finally, the impedance tuner circuit 120 according to the present disclosure can reduce the amplitude of the second signal S2 provided to the input terminal of the amplifier 140 by reducing the conversion gain of the mixer 110. In this case, the leakage component LE output by the amplifier 140 with a fixed leakage gain G_LE can be relatively reduced from P2 to P5. When the leakage component LE becomes lower, the lower limit of the dynamic range also becomes lower, so the dynamic range can be ensured. In addition, the amplifier 140 amplifies the second signal S2 in the low power mode according to the increased amplifier gain, thereby outputting the amplified RF signal D_RF, which has the desired output power despite the reduced conversion gain.

[0051] Figure 4 and Figure 5 RF band characteristics according to conversion gain control according to some embodiments are shown.

[0052] First, refer to Figure 4 , the case where the conversion gain of the mixer 110 is adjusted ("changing w / MN") only by the tunable matching network 130 can be considered as an example. In the case of the tunable matching network 130, the conversion gain can be adjusted by changing the impedance. The operation of the matching network 130 deviating from the "pre-tuned (matched) impedance for conversion gain control" can be defined as misadjustment (or mismatch state). Through the misadjustment, it can be seen that the gain of the RF waveform is gradually adjusted within the required RF bandwidth RF BW. However, the misadjustment inevitably involves changing the matching frequency, so that the center frequency of the RF waveform becomes more and more distorted, and it can be seen that the band flatness of the RF waveform also collapses within the RF bandwidth RF BW.

[0053] Finally, when the conversion gain is adjusted through the tunable matching network 130 , the desired frequency may not be met and the frequency band flatness may also be destroyed.

[0054] Next, refer to Figure 5According to some embodiments, the matching network 130 may be fixed, but the conversion gain of the mixer 110 may be adjusted ("changed w / ITC") via the impedance tuner circuit 120. In this case, it can be seen that the gain is adjusted while the RF waveform maintains the center frequency within the RF bandwidth RF BW. Thus, according to the RF circuit of the present disclosure, the required frequency specifications may be met while maintaining the frequency band flatness of the RF waveform. Additionally, due in part to the gain control, the dynamic range may be wider.

[0055] Figure 6 The RF circuit 200 is shown when the impedance tuner circuit 220 is disconnected, according to some embodiments.

[0056] Reference Figure 6 , the RF circuit 200 according to some embodiments may further include a logic circuit 250 for controlling the impedance tuner circuit 220. The logic circuit 250 may be configured to change the impedance of the impedance tuner circuit 220 based on a gain index GI for gain control of the RF circuit 200. The gain index GI may be defined as an index corresponding to a gain level required by the RF circuit 200. For example, when at least one of the impedance tuner circuit 220 and the amplifier 240 is operating, the gain of the RF circuit 200 required at a specific gain index GI may be adjusted. There may be various situations in which the logic circuit 250 receives a command signal from an external source (not shown) to change the gain index. For example, if the RF circuit 200 is part of a portable wireless device, the base station may request the wireless device to reduce the output power of the wireless device when a lower power signal is sufficient for communication.

[0057] The logic circuit 250 may control the impedance tuner circuit 220 (using the control signal CC) to have an impedance level sufficient to achieve the overall RF circuit 200 gain corresponding to a specific gain index GI. For example, as shown, the impedance tuner circuit 220 may include one or more variable impedance circuits VZ1 to VZn (where n is a positive integer). Any variable impedance circuit (such as VZn) may include a switch (e.g., SWn) connected in series with a fixed impedance Zn, wherein the switch SWn is controlled by the control signal CC to open or close. The logic circuit 250 may control the impedance tuner circuit 220 to have a desired impedance level at a specific gain index GI based on turning on / off one or more variable impedance circuits VZ1 to VZn (e.g., by closing / opening a corresponding switch (such as SWn) in each of the impedance circuits VZ1 to VZn). In addition, under the control of the logic circuit 250, the impedance tuner circuit 220 may gradually adjust the conversion gain of the mixer 210 based on changing one or more variable impedance circuits VZ1 to VZn.

[0058] When the entire impedance tuner circuit 220 is to be disconnected at a specific gain index GI, the logic circuit 250 may disconnect the impedance tuner circuit 220. For example, when the impedance tuner circuit 220 is disconnected, the variable impedance circuits VZ1 to VZn may all be deactivated (ie, the impedance of each variable impedance circuit may be infinite).

[0059] In this case, when other impedances included in the load impedance do not change, the load impedance of the mixer 210 may have an optimized value (to achieve a maximum signal level of the signal S2). Therefore, when the impedance tuner circuit 220 is disconnected, the conversion gain CG1 of the mixer 210 may be maximized.

[0060] According to some embodiments, when the RF circuit 200 operates in the high power mode, the logic circuit 250 may disconnect the impedance tuner circuit 220. In this case, the gain level corresponding to the gain index GI in the high power mode will be higher. For example, the logic circuit 250 may determine whether to operate in the high power mode based on the gain index GI. When the impedance tuner circuit 220 is disconnected, the load impedance of the mixer 210 may increase so that the mixer 210 has a maximized conversion gain CG1. Finally, the second signal S2 output to the matching network 230 and the amplifier 240 by the mixer 210 may meet the target output power in the high power mode.

[0061] Figure 7 and Figure 8 The RF circuit is shown when the impedance tuner circuit is turned on, according to some embodiments.

[0062] Reference Figure 7 and Figure 8 , when the impedance tuner circuit 220 is to be turned on at a specific gain index GI, the logic circuit 250 may turn on the impedance tuner circuit 220. The logic circuit 250 may reduce the conversion gain by turning on the impedance tuner circuit 220 at the k-th value (wherein "k" is a positive integer) of the gain index GI. For example, when the impedance tuner circuit 220 is turned on, one or more variable impedance circuits VZ1 to VZn may be activated (i.e., the impedance of each variable impedance circuit may have a value other than infinity). In addition, when the impedance tuner circuit 220 is implemented in a differential structure, the conversion gain may be adjusted by adjusting "the amount by which the differential output signals of the mixer 210 thereof cancel each other as the impedance changes".

[0063] According to some embodiments, each of the one or more variable impedance circuits VZ1 to VZn may be operated in a switchable manner and may have an array structure formed in parallel. The one or more variable impedance circuits VZ1 to VZn may have variable impedances that are the same as or different from each other. When the one or more variable impedance circuits VZ1 to VZn are activated, the equivalent impedance VZ (see Figure 1 When the number of the one or more variable impedance circuits VZ1 to VZn increases, or when the equivalent impedance value that can be combined according to the one or more variable impedance circuits VZ1 to VZn increases, finer conversion gain control may be possible.

[0064] When the impedance tuner circuit 220 is turned on, the impedance tuner circuit 220 may have an impedance that changes depending on the number of activated variable impedance circuits. Figure 7 In the case of , since the nth variable impedance circuit VZn is turned on, the impedance tuner circuit 220 may have an impedance Zn corresponding to the nth variable impedance circuit VZn. Figure 8 In the case of , since the first variable impedance circuit VZ1 is turned on and the remaining impedance circuits are turned off, the impedance tuner circuit 220 may have an impedance Z1 corresponding to the first variable impedance circuit VZ1.

[0065] When Zn is greater than Z1, Figure 7 The load impedance in Figure 8 The load impedance in. Therefore, Figure 7 The conversion gain CG2 will also be greater than Figure 8 Finally, the logic circuit 250 may adjust the conversion gain by changing the impedance of the impedance tuner circuit 220 according to the gain level corresponding to the gain index GI.

[0066] According to some embodiments, when the RF circuit 200 operates in the low power mode, the logic circuit 250 may turn on the impedance tuner circuit 220. In this case, the gain level corresponding to the gain index GI in the low power mode will be low. For example, the logic circuit 250 may determine whether to operate in the low power mode based on the gain index GI. When the impedance tuner circuit 220 is turned on, the load impedance of the mixer 210 is reduced, so the mixer 210 may have a conversion gain CG2 or CG3. Specifically, depending on the output power required in the low power mode, the conversion gain can be adjusted in various ways. For example, the impedance tuner circuit 220 may activate one or more variable impedance circuits VZ1 to VZn to increase the impedance so that the mixer 210 has a higher conversion gain CG2. For example, the impedance tuner circuit 220 may activate one or more variable impedance circuits VZ1 to VZn to reduce the impedance so that the mixer 210 has a lower conversion gain CG3.

[0067] Fig. 9 The relationship between load impedance and conversion gain according to some embodiments is shown.

[0068] Reference Fig. 9 According to the embodiments described above, the impedance tuner circuit of the present disclosure can gradually adjust the load impedance of the mixer by activating one or more variable impedance circuits. Fig. 9 In detail, the “adjustment width W by which the load impedance is adjusted” may be determined depending on how finely the impedance tuner circuit can adjust the impedance. For example, as more variable impedance circuits included in the impedance tuner circuit are set, the adjustment width W may be more precise. In addition, as shown, as the load impedance increases (that is, as the impedance of the impedance tuner circuit increases), the conversion gain may increase.

[0069] Fig.10 The relationship between the gain index and the output of an amplifier according to some embodiments is shown.

[0070] Reference Fig.10 According to some embodiments, according to a change in the gain index, the output power (Pout) of the amplifier may change for situations where the impedance tuner circuit ("w / ICT") is set and the impedance tuner circuit is not set ("w / o ICT"). For example, assuming that the dynamic range required for the entire transmission path including the RF circuit is approximately 80dBm, and a gain control of approximately 15dBm is feasible in the power amplifier PA connected to the RF circuit, ultimately, it can be seen that a gain control of approximately 65dBm is required in the RF circuit. Whenever the gain index changes by "1", the amplifier can adjust the gain in units of a specific size. Fig.10In the example, the gain can be adjusted in units of about 6 dBm. Also, assume that the input to the amplifier is about -10 dBm in this example, and the fixed leakage gain due to the implementation of the amplifier is about -40 dB.

[0071] Due to the leakage gain, in the case of w / o ICT, a first leakage component LE1 of about -50dBm may be output. This first leakage component LE1 serves as the lower limit of the dynamic range, so it can be confirmed that the gain does not drop below this lower limit despite the adjustment of the gain index. However, in the case of w / o ICT, the dynamic range defined by the maximum and minimum values ​​of the output power is about 55dBm, so the gain control capability (about 65dB) required by the RF circuit is not satisfied.

[0072] In contrast, in the case of w / ICT, by reducing the conversion gain of the mixer through the impedance tuner circuit at the 10th value of the gain index, the output of the mixer (i.e., the input of the amplifier) ​​is reduced from about -10 dBm to about -22 dBm. Therefore, based on the fixed leakage gain (-40 dB), the second leakage component LE2 for w / ICT can have a further reduced value of about -62 dBm. In the case of w / ICT, the lower limit can be lower.

[0073] Finally, in the case of the w / ICT example, the dynamic range is further improved to about 67dBm, so the gain control capability (about 65dB) required by the RF circuit can be met. By ensuring an additional gain control capability of about 12dB under w / ICT, the load of the dynamic range responsible for the amplifier can be reduced, and the optimal design of the amplifier is feasible, and this can also avoid the limitation of the dynamic range caused by the lower limit.

[0074] Fig.11 A layout of an RF circuit according to some embodiments is shown.

[0075] Reference Fig.11 , the layout 300 of the RF circuit may include a mixer 310, a routing line 320, an impedance tuner circuit 330, a matching network 340, an amplifier input line 350, and an amplifier 360. The output terminal of the mixer 310 is connected to the impedance tuner circuit 330 through the routing line 320, and the impedance tuner circuit 330 may be connected to the matching network 340. When a plurality of mixers 310 are provided, the routing line 320 may be configured to combine the outputs of the plurality of mixers 310 to provide a composite output that may be transmitted to the impedance tuner circuit 330.

[0076] Matching network 340 may be connected to an input terminal of amplifier 360 via amplifier input line 350. As described above, matching network 340 may be implemented based on an LC tank or a transformer, and may include at least one inductor and at least one capacitor depending on the implementation.

[0077] According to some embodiments described above, the impedance tuner circuit 330 disposed between the routing line 320 and the matching network 340 may be configured to be switched on / off to adjust the load impedance and conversion gain of the mixer 310 .

[0078] Fig.12 is a flow chart illustrating a method of operating an RF circuit according to some embodiments.

[0079] Reference Fig.12 In operation S110, the RF circuit may adjust the conversion gain of the mixer by changing the impedance of the impedance tuner circuit. For example, when the impedance tuner circuit is disconnected, the conversion gain of the mixer may increase. In operation S120, the RF circuit may convert the first signal into the second signal using the LO signal and the conversion gain adjusted in operation S110. The second signal converted by the mixer may have an amplitude corresponding to the adjusted conversion gain. In operation S130, the RF circuit may amplify the second signal.

[0080] Fig.13 is a flow chart illustrating a method for adjusting the impedance of an RF circuit according to some embodiments.

[0081] Reference Fig.13 , in operation S210, the RF circuit may determine whether to operate in the high power mode. For example, the RF circuit may determine whether to operate in the high power mode or the low power mode based on the gain index. For example, when the output power according to the gain corresponding to the gain index is greater than or equal to the first threshold, the RF circuit may determine the operation as the high power mode, and when the output power is less than or equal to the second threshold, the RF circuit may determine the operation as the low power mode. The first threshold and the second threshold may be the same in some embodiments, and may be different in other embodiments.

[0082] When the operation is determined to be the high power mode, the RF circuit may disconnect the impedance tuner circuit in operation S220. When the impedance tuner circuit is disconnected, the load impedance of the mixer may be increased or optimized to maximize the conversion gain of the mixer.

[0083] Optionally, the operation is determined to be a low power mode, and in operation S230, the RF circuit can change the impedance by turning on the impedance tuner circuit. When the impedance of the impedance tuner circuit changes in a decreasing direction, the load impedance of the mixer will also be reduced (or may be changed to cause mismatch), so the conversion gain of the mixer will decrease.

[0084] Fig.14 A wireless communication apparatus is shown in accordance with some embodiments.

[0085] Reference Fig.14 , the wireless communication device 400 may include a modem 410, an RF integrated circuit (RFIC) 420, a power amplifier PA, a duplexer 430, a power modulator 440, and an antenna ANT.

[0086] The modem 410 may include a digital processing circuit (DPC) 411, a first digital-to-analog converter (DAC) 412, a second DAC 413, an analog-to-digital converter (ADC) 414, and a mobile industry processor interface (MIPI). The modem 410 may process a baseband signal BB_T (eg, including an I signal and a Q signal) containing information to be transmitted through the digital processing circuit 411 according to various communication methods. The modem 410 may process a received baseband signal BB_R through the digital processing circuit 411 according to various communication methods.

[0087] For example, the modem 410 may process a signal to be transmitted or a received signal according to a communication scheme such as OFDM (Orthogonal Frequency Division Multiplexing), OFDMA (Orthogonal Frequency Division Multiple Access), WCDMA (Wideband Code Multiple Access), or HSPA+ (High Speed ​​Packet Access+). In addition, the modem 410 may process the baseband signal BB_T or BB_R according to various types of communication methods (i.e., various communication methods to which a technique for modulating or demodulating the amplitude and frequency of the baseband signal BB_T or BB_R is applied).

[0088] According to some embodiments, the modem 410 may extract the envelope of the baseband signal BB_T through the digital processing circuit 411 , and may generate a digital envelope signal D_ENV based on the extracted envelope.

[0089] According to some embodiments, the modem 410 may generate an average power signal D_REF based on an average power tracking (APT) table stored in a memory. The APT table may store information of a necessary power supply voltage of the power amplifier PA according to an expected output power (or transmission power) of the antenna ANT, and may store information of the average power signal D_REF corresponding to the necessary power supply voltage of the power amplifier PA. Therefore, when the expected output power of the antenna ANT is determined, the modem 410 may generate the average power signal D_REF by using the APT table, and may provide the generated average power signal D_REF as a reference voltage signal to the power modulator 440.

[0090] Digital processing circuitry 411 may perform various processing operations on the baseband signal in the digital domain.

[0091] For example, the digital processing circuit 411 may perform the above-described average power signal generation, envelope extraction operations, digital envelope signal generation, crest factor reduction (CFR), shape function (SF), digital predistortion (DPD), delay correction operations, and the like.

[0092] CFR can reduce the peak-to-average power ratio (PAPR) of a communication signal (e.g., baseband signal BB_T). SF can transform the digital envelope signal D_ENV to improve the efficiency and linearity of the power amplifier PA. DPD can linearize the distortion of the power amplifier PA by compensating for the distortion in the digital domain. In addition, the delay correction operation can correct the delay of the digital envelope signal D_ENV or the baseband signal BB_T.

[0093] The digital processing circuit 411 may output a digital envelope signal D_ENV and a baseband signal BB_T. In addition, the digital envelope signal D_ENV may be converted into an analog envelope signal A_ENV by a first digital-to-analog converter 412 to be provided to the power modulator 440, and the baseband signal BB_T may be converted into a transmission signal TX by a second DAC 413 to be provided to the transmission circuit TXC.

[0094] Although not shown in the drawings, the digital processing circuit 411 may further include internal components for processing the above operations (ie, baseband signal processing, envelope extraction, and digital envelope signal generation).

[0095] The second DAC 413 and the ADC 414 may be set in one or more quantities. The modem 410 may convert the baseband signal BB_T into an analog signal using the second DAC 413 to generate a transmission signal TX. In addition, the modem 410 may receive a reception signal RX as an analog signal from the RFIC 420. In addition, the modem 410 may digitally convert the reception signal RX through the ADC 414 provided therein, and may extract the baseband signal BB_R as a digital signal. For example, the reception signal RX may be a differential signal including a positive signal and a negative signal.

[0096] RFIC 420 may generate an RF input signal RF_IN by up-converting a transmission signal TX, or may generate a reception signal RX by down-converting an RF reception signal RF_R. To this end, RFIC 420 may include a transmission circuit TXC for up-conversion, a reception circuit RXC for down-conversion, and a local oscillator LO.

[0097] In this case, the transmission circuit TXC may include a first analog baseband filter ABF1, a first mixer MX1, an impedance tuner circuit 421, and a driving amplifier 422. For example, the first analog baseband filter ABF1 may include a low pass filter.

[0098] The first analog baseband filter ABF1 may filter the transmission signal TX received from the modem 410, and may provide the filtered signal to the first mixer MX1. Here, the first analog baseband filter ABF1 may filter the baseband signal. In addition, the first mixer MX1 ​​may perform up-conversion to convert the frequency of the transmission signal TX from the baseband to the high frequency band using the frequency signal provided by the local oscillator LO. In this case, the first mixer MX1 ​​may be the above-described Figures 1 to 3 and Figures 6 to 8 Through the up-conversion, the transmission signal TX can be provided as the RF input signal RF_IN to the driver amplifier 422, and the driver amplifier 422 can first amplify the power of the RF input signal RF_IN to provide the amplified result to the power amplifier PA.

[0099] According to some embodiments, the impedance tuner circuit 421 may be disposed between the first mixer MX1 ​​and the driver amplifier 422. The impedance tuner circuit 421 may be configured as described above. Figures 1 to 3 and Figures 6 to 8 The impedance tuner circuit 421 may be configured to adjust the conversion gain of the first mixer MX1 ​​by changing the impedance of the impedance tuner circuit 421 .

[0100] For example, when the power amplifier PA operates in a high power mode, the impedance tuner circuit 421 may be disconnected, in which case the output power of the power amplifier PA is greater than or equal to the first threshold. When the impedance tuner circuit 421 is disconnected, the conversion gain may be maximized.

[0101] For example, the impedance tuner circuit 421 may be turned on based on the power amplifier PA operating in a low power mode, in which the output power of the power amplifier PA is less than or equal to the second threshold value. When the impedance of the impedance tuner circuit 421 changes in a decreasing direction, the conversion gain of the first mixer MX1 ​​will also decrease. When the conversion gain is adjusted by the impedance tuner circuit 421, the power of the output signal of the first mixer MX1 ​​will also change. Here, when the impedance of the impedance tuner circuit 421 is reduced, the conversion gain will decrease, so the output signal of the first mixer MX1 ​​may have a lower power. Therefore, controlling the conversion gain of the first mixer MX1 ​​by the impedance tuner circuit 421 may help reduce the size of the leakage component of the driver amplifier 422.

[0102] The power amplifier PA may be supplied with a DC voltage or a variable power supply voltage (ie, a dynamically variable output voltage), and may secondary amplify the power of the RF input signal RF_IN based on the supplied power supply voltage to generate an RF output signal RF_OUT. In addition, the power amplifier PA may provide the generated RF output signal RF_OUT to the duplexer 430.

[0103] According to some embodiments described above, the load impedance of the mixer MX1 ​​can be adjusted by the impedance tuner circuit 421 provided at the front end of the power amplifier PA, depending on whether the output power required by the power amplifier PA is high power or low power. In particular, in the low power mode, the conversion gain of the first mixer MX1 ​​is adjusted according to the load impedance control, and the input signal of a lower level can be applied to the driver amplifier 422 by the conversion gain control. Therefore, the driver amplifier 422 can extend the dynamic range by outputting a lower leakage component. Ultimately, the dynamic range of the transmission chain including the transmission circuit TXC and the power amplifier PA can be improved.

[0104] The receiving circuit RXC may include a second analog baseband filter ABF2, a second mixer MX2, and a low noise amplifier (LNA) 423. For example, the second analog baseband filter ABF2 may include a low pass filter.

[0105] The LNA 423 may amplify the RF reception signal RF_R provided from the duplexer 430, and then the amplified RF reception signal RF_R is provided to the second mixer MX2. In addition, the second mixer MX2 may perform down-conversion to convert the frequency of the reception signal RF_R from a high frequency band to a baseband using a frequency signal provided by the local oscillator LO. Through the down-conversion, the RF reception signal RF_R may be provided as a reception signal RX to the second analog baseband filter ABF2, and the second analog baseband filter ABF2 may filter the reception signal RX, and then the filtered reception signal RX is provided to the modem 410.

[0106] In one embodiment, the wireless communication device 400 may transmit the transmission signal through multiple frequency bands by using carrier aggregation (CA). In addition, for this purpose, the wireless communication device 400 may include multiple power amplifiers PA, and the multiple power amplifiers PA amplify the power of multiple RF input signals RF_IN corresponding to multiple carriers respectively. However, in this discussion, for the convenience of description, the description will be given when the number of power amplifiers is "1".

[0107] The duplexer 430 may be connected to the antenna ANT and may separate the transmission frequency from the reception frequency. In detail, the duplexer 430 may separate the RF output signal RF_OUT provided from the power amplifier PA for each frequency band so as to be provided to the corresponding antenna ANT. In addition, the duplexer 430 may provide an external signal provided from the antenna ANT to the LNA 423 included in the receiving circuit RXC of the RFIC 420. For example, the duplexer 430 may include a front end module (FEMiD) having an integrated duplexer.

[0108] In one embodiment, the wireless communication device 400 may include a switch structure capable of separating the transmission frequency and the reception frequency instead of the duplexer 430. In addition, the wireless communication device 400 may include a structure implemented with the duplexer 430 and the switch for the purpose of separating the transmission frequency and the reception frequency. However, for ease of description, the embodiments of the present disclosure will be described as including the duplexer 430 capable of separating the transmission frequency and the reception frequency in the wireless communication device 400.

[0109] The power modulator 440 may generate a modulated output voltage whose level is dynamically changed based on the analog envelope signal A_ENV and the average power signal D_REF, and may provide the modulated output voltage as a power voltage to the power amplifier PA.

[0110] In detail, the power modulator 440 may be provided with an average power signal D_REF and an analog envelope signal A_ENV from the modem 410. The power modulator 440 may be driven in a tracking mode corresponding to one of an envelope tracking (ET) mode and an APT mode based on the average power signal D_REF and the analog envelope signal A_ENV provided thereby, and may generate a dynamically variable output voltage. In addition, the power modulator 440 may supply the generated output voltage as a power supply voltage to the power amplifier PA.

[0111] For example, when a fixed level of power supply voltage is applied to the power amplifier PA, the power efficiency of the power amplifier PA may be reduced. Therefore, in order to effectively manage the power of the power amplifier PA, the power modulator 440 may modulate the input voltage (i.e., the power supplied from the battery) based on at least one of the analog envelope signal A_ENV and the average power signal D_REF, and may provide the modulated voltage as the power supply voltage to the power amplifier PA.

[0112] The antenna ANT may transmit the RF output signal RF_OUT frequency-separated by the duplexer 430 to the outside, or may provide the RF reception signal RF_R received from the outside to the duplexer 430. For example, the antenna ANT may include, but is not limited to, an array antenna.

[0113] For reference, each of the modem 410, the RFIC 420, the power amplifier PA, the duplexer 430, and the power modulator 440 may be implemented separately with an integrated circuit, a chip, or a module. In addition, the modem 410, the RFIC 420, the power amplifier PA, the duplexer 430, and the power modulator 440 may be mounted together on a printed circuit board (PCB). However, the technical concept of the present disclosure is not limited thereto, and in some embodiments, at least part of the modem 410, the RFIC 420, the power amplifier PA, the duplexer 430, and the power modulator 440 may be implemented with a single communication chip.

[0114] in addition, Fig.14 The wireless communication device 400 shown in FIG. 4 may be included in a wireless communication system using a cellular network (such as 5G, LTE), and may also be included in a wireless local area network (WLAN) system or any other wireless communication system. In one embodiment, Fig.14 The configuration of the wireless communication device 400 shown in FIG. 4 is an exemplary embodiment, but is not limited thereto, and may be variously configured according to a communication protocol or a communication scheme.

[0115] Fig.15 An IoT (Internet of Things (IOT)) device to which a wireless communication device is applied according to some embodiments is shown.

[0116] Reference Fig.15 , IoT may refer to a network between things using wired and / or wireless communications. An IOT device may include an accessible wired or / and wireless interface, and may include a device that communicates with one or more other devices to send or receive data via a wired or / and wireless interface. The accessible interface included in an IoT product may include a modem communication interface, which may access a local area network (LAN), a wireless local area network (WLAN) such as wireless fidelity (Wi-Fi), a wireless personal area network (WPAN) such as Bluetooth, a wireless universal serial bus (USB), Zigbee, near field communication (NFC), radio frequency identification (RFID), power line communication (PLC), or a mobile cellular network (such as, third generation (3G), long term evolution (LTE), fourth generation (4G), or fifth generation (5G)). The Bluetooth interface may support Bluetooth low energy (BLE).

[0117] In detail, the IOT device 500 may include a communication interface 510 (radio transceiver / receiver) for communicating with the outside. The communication interface 510 may be, for example, a modem communication interface, which may access a wireless local area network (such as LAN, Bluetooth, Wi-Fi or Zigbee, PLC), a mobile communication network (such as 3G, LTE, 4G or 5G), etc. The communication interface 510 may include a transceiver and / or a receiver. The IOT device 500 may send and / or receive information from an access point or a gateway via a transceiver and / or a receiver. In addition, the IOT device 500 may communicate with a user device or any other IOT device to send and / or receive control information or data of the IOT device 500.

[0118] Refer to above Fig.14 The wireless communication device 400 described above may be implemented in the communication interface 510, and accordingly, the above reference Fig.14 At least one of the described power modulators 440 may be implemented in a transmitting unit of the communication interface 510 .

[0119] The IOT device 500 may also include a processor or an application processor (AP) 520 that performs calculations. For an internal power source, the IOT device 500 may also include an embedded battery or a power supply unit powered from an external source. In addition, the IOT device 500 may include a display 540 for displaying an internal state or data. A user may control the IOT device 500 through a user interface (UI) of the display 540 in the IOT device 500. The IOT device 500 may send an internal state and / or data to the outside through a transceiver, and may receive control instructions and / or data from the outside through a receiver.

[0120] The memory 530 may store control instruction codes, control data or user data for controlling the IOT device 500. The memory 530 may include at least one of a volatile memory and a non-volatile memory. The non-volatile memory includes at least one of various memories such as a read-only memory (ROM), a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a flash memory, a phase change RAM (PRAM), a magnetic RAM (MRAM), a resistive RAM (ReAM) and a ferroelectric RAM (FRAM). The volatile memory may include at least one of various memories such as a static RAM (SRAM), a dynamic RAM (DRAM) and a synchronous DRAM (SDRAM).

[0121] The IoT device 500 may further include a storage device. The storage device may include at least one of a non-volatile medium such as a solid state drive (SSD), an embedded multimedia card (eMMC), and a universal flash storage (UFS). The storage device may store user information provided through an input / output unit (I / O) 550 and a plurality of sensing information collected through a sensor 560.

[0122] Fig.16 A mobile terminal to which a wireless communication device is applied according to some embodiments is shown.

[0123] Reference Fig.16 , the mobile terminal 600 may include an application processor (hereinafter, referred to as “AP”) 610, a memory 620, a display 630, and an RF module 640. In addition, the mobile terminal 600 may further include various components such as a lens and an audio module.

[0124] The AP 610 may be implemented with a system on chip (SoC) and may include a central processing unit (CPU) 611, a RAM 612, a power management unit (PMU) 613, a memory interface (I / F) 614, a display controller (DCON) 615, a modem 616, and a system bus 617. In addition, the AP 610 may also include various intellectual property rights. The AP 610 may have the function of a modem chip integrated therein, and the AP 610 is called a "ModAP".

[0125] The CPU 611 may control the overall operation of the AP 610 and the mobile terminal 600. The CPU 611 may control the operation of each component of the AP 610. In addition, the CPU 611 may be implemented with a multi-core. The multi-core may be one computing component having two or more independent cores.

[0126] The RAM 612 may temporarily store programs, data, or instructions. For example, the programs and / or data stored in the memory 620 may be temporarily stored in the RAM 612 under the control of the CPU 611 or according to the boot code. The RAM 612 may be implemented with DRAM or SRAM.

[0127] The PMU 613 may manage power of each component of the AP 610. The PMU 613 may also determine an operating condition of each component of the AP 610, and may control the operation of each component of the AP 610.

[0128] The memory interface 614 may control the overall operation of the memory 620, and may control data exchange between the memory 620 and each component of the AP 610. The memory interface 614 may write data to the memory 620 or read data from the memory 620 according to a request of the CPU 611.

[0129] The display controller 615 may provide the display 630 with image data to be displayed on the display 630. The display 630 may be implemented with a flat panel display such as a liquid crystal display (LCD) or an organic light emitting diode (OLED) display, or a flexible display.

[0130] For wireless communication, the modem 616 can modulate data to be transmitted in a manner suitable for the wireless environment and can recover received data. The modem 616 can perform digital communication with the RF module 640.

[0131] For reference, modem 616 may be used as described above. Fig.14 The described modem 410 is implemented.

[0132] The RF module 640 may convert a high frequency signal received through the antenna into a low frequency signal, and may transmit the converted low frequency signal to the modem 616. In addition, the RF module 640 may convert a low frequency signal received from the modem 616 into a high frequency signal, and may transmit the converted high frequency signal to a free space through the antenna. In addition, the RF module 640 may amplify or filter the signal.

[0133] For example, in the RF module 640, the above reference Fig.14 The RFIC 420, power amplifier PA, duplexer 430, power modulator 440 and antenna ANT are described.

[0134] For this reason, in the mobile terminal 600 , broadband communication may be possible, and power consumption for communication may be reduced.

[0135] According to an embodiment of the present disclosure, an RF circuit capable of controlling a conversion gain of a mixer and a method of operating the RF circuit may be provided.

[0136] The above description is a specific embodiment for carrying out the present disclosure. Although the present disclosure has been described with reference to the embodiments of the present disclosure, it will be apparent to those skilled in the art that various changes and modifications may be made thereto without departing from the spirit and scope of the present disclosure as set forth in the appended claims.

Claims

1. A radio frequency circuit, comprising: a mixer configured to convert the first signal into a second signal using a local oscillator signal; an amplifier configured to amplify the second signal; as well as The impedance tuner circuit is connected between the mixer and the input terminal of the amplifier and is configured to adjust the conversion gain of the mixer by presenting a variable impedance.

2. The radio frequency circuit according to claim 1, further comprising: The matching network is connected between the impedance tuner circuit and the input terminal of the amplifier and is configured to match the impedance between the mixer and the amplifier.

3. The radio frequency circuit according to claim 1, wherein: The impedance tuner circuit is controlled to have an impedance that changes based on an output power of the radio frequency circuit.

4. The radio frequency circuit according to claim 3, wherein: When the radio frequency circuit operates in a high power mode, the impedance tuner circuit is disconnected. In the high power mode, the output power of the radio frequency circuit is greater than or equal to a first threshold.

5. The radio frequency circuit according to claim 3, wherein: When the radio frequency circuit operates in a low power mode, the impedance tuner circuit is turned on. In the low power mode, the output power of the radio frequency circuit is less than or equal to a second threshold.

6. The radio frequency circuit according to claim 4, wherein: When the impedance tuner circuit is disconnected, the conversion gain is maximized.

7. The radio frequency circuit according to claim 1, wherein: The impedance tuner circuit includes one or more variable impedance circuits.

8. The radio frequency circuit according to claim 7, wherein: The impedance tuner circuit is configured to adjust the conversion gain in steps by varying the one or more variable impedance circuits in a corresponding stepwise manner.

9. The radio frequency circuit according to any one of claims 1 to 8, further comprising: A logic circuit is configured to change an impedance of an impedance tuner circuit based on a gain index for gain control of the radio frequency circuit.

10. The radio frequency circuit according to claim 9, wherein: The logic circuit switches on the impedance tuner circuit at a kth value of the gain index to reduce the conversion gain, wherein k is a positive integer.

11. The radio frequency circuit according to claim 10, wherein: The amplifier amplifies the second signal with an amplifier gain adjusted to compensate for the reduction in conversion gain.

12. The radio frequency circuit according to claim 10, wherein: When amplifying the second signal, the amplifier outputs a leakage component that decreases as the conversion gain decreases.

13. The radio frequency circuit according to claim 1, wherein: The mixer is implemented as a passive mixer.

14. A wireless communication device, comprising: a radio frequency integrated circuit configured to up-convert a baseband signal to output a radio frequency signal, and A power amplifier is configured to amplify the radio frequency signal. Among them, radio frequency integrated circuits include: a mixer configured to convert the baseband signal into a radio frequency signal using a local oscillator signal; an amplifier configured to amplify the radio frequency signal; and The impedance tuner circuit is connected between the mixer and the input terminal of the amplifier and is configured to adjust the conversion gain of the mixer by presenting a variable impedance.

15. The wireless communication device according to claim 14, wherein: When the power amplifier operates in a high power mode, the impedance tuner circuit is disconnected, and when the power amplifier operates in a low power mode, the impedance tuner circuit is turned on. In the high power mode, the output power of the power amplifier is greater than or equal to a first threshold, and in the low power mode, the output power is less than or equal to a second threshold.

16. The wireless communication device according to claim 14, wherein: When the impedance tuner circuit is disconnected, the conversion gain is maximized.

17. The wireless communication device according to claim 14, wherein: The impedance tuner circuit includes one or more variable impedance circuits, and Wherein the impedance tuner circuit is configured to: gradually adjust the conversion gain by changing the one or more variable impedance circuits in a corresponding stepwise manner.

18. The wireless communication device according to claim 14, wherein: The radio frequency integrated circuit also includes: a baseband filter, which is used to filter the baseband signal.

19. A method of operating a radio frequency circuit, the method comprising: The conversion gain of the mixer is adjusted by changing the impedance of the impedance tuner circuit; converting the first signal into a second signal using a local oscillator signal applied to a mixer; as well as The second signal is amplified.

20. The method according to claim 19, wherein: The step of adjusting the conversion gain comprises: When the RF circuit operates in a high power mode, disconnecting the impedance tuner circuit, wherein the output power of the RF circuit is greater than or equal to a first threshold in the high power mode; and When the radio frequency circuit operates in a low power mode, the impedance tuner circuit is turned on, and in the low power mode, the output power is less than or equal to a second threshold.

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