Communication and phase shift integrated multifunctional mixer structure

Abstract

The invention discloses a communication and phase shift integrated multifunctional mixer structure, which comprises a mixer core used for phase adjustment or frequency mixing modulation, and also comprises an orthogonal signal generator of which the output end is electrically connected with the first input end of the mixer core and which is used for generating a differential orthogonal signal; the input end of the reconfigurable matching network is connected with the frequency mixing output end of the frequency mixer core, and the output end of the reconfigurable matching network is connected with the output buffer amplifier; the digital-to-analog converter is used for converting the input I-path digital baseband signal and the Q-path digital baseband signal into analog signals; and the output end of the switch type low-pass filter is electrically connected with the second input end of the mixer core, and the input end of the switch type low-pass filter is electrically connected with the output end of the digital-to-analog converter. According to the invention, functions of communication and phase shift can be realized at the same time, and the problem of impedance mismatch caused by large output impedance difference of the mixer in two states of communication and phase shift can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of mixers, and in particular to a multifunctional mixer structure integrating communication phase shifting. Background Art

[0002] With the continuous development of integrated communication and perception technologies, the Internet of Everything is gradually becoming a reality. Integrated communication and perception technologies are driving the rapid development of multiple fields. For example, with the increasing adoption of intelligent driving technologies and the rapid increase in connected and autonomous vehicles, the demand for wireless spectrum resources in vehicle networks is rapidly increasing. To significantly enhance the collaborative perception capabilities of intelligent vehicles, establish vehicle-cloud server interconnection, and enhance driving safety, vehicle networks can utilize millimeter-wave radar spectrum for communication. In-vehicle radars based on integrated communication and perception will become a core component of future intelligent vehicles. This will play a significant role in enhancing the collaborative perception capabilities of intelligent vehicles, establishing vehicle-cloud server interconnection, and enhancing driving safety. Integrated communication and perception technologies will also play a crucial role in other areas such as smart transportation, smart homes, social governance, smart medical treatment, and drone-based low-altitude security. However, achieving integrated communication and perception technologies also places higher demands and challenges on RF front-end chips.

[0003] Because sensing and communication operate in different modes and require different transceiver architectures, current radar chips generally lack communication functionality. Implementing both communication and sensing functions within the same transceiver chip presents significant challenges for each module within the transceiver. The mixer in the transmitter performs frequency mixing and modulation in the communication mode. In the sensing mode, the mixer should also have phase shifting capabilities, as existing high-performance radars commonly include phase shifting. However, due to the limitations of conventional mixer circuit structures, conventional mixer chips cannot simultaneously implement both communication and phase shifting functions. Furthermore, the mixer's bias points differ significantly between the phase shift and communication modes, resulting in different output impedances. This results in a significant impedance mismatch between the mixer and the output buffer amplifier, reducing the overall transmitter gain. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is: to propose a multifunctional mixer structure with integrated communication and phase shifting, which can realize both communication and phase shifting functions and avoid the problem of impedance mismatch caused by the large difference in output impedance of the mixer in the communication and phase shifting states.

[0005] A technical solution adopted by the present invention is to provide a multifunctional mixer structure with integrated communication phase shifting, including a mixer core for adjusting phase or mixing modulation, and also including:

[0006] an orthogonal signal generator, an output end of which is electrically connected to the first input end of the mixer core, for generating differential orthogonal signals;

[0007] a reconfigurable matching network, wherein an input end of the reconfigurable matching network is connected to a mixing output end of the mixer core, and an output end of the reconfigurable matching network is connected to an output buffer amplifier, wherein the output buffer amplifier is used to adjust the output impedance of the mixer core in a communication state;

[0008] A digital-to-analog converter, used for converting the input I-channel digital baseband signal and Q-channel digital baseband signal into analog signals;

[0009] The switching low-pass filter has an output terminal electrically connected to the second input terminal of the mixer core, and an input terminal electrically connected to the output terminal of the digital-to-analog converter.

[0010] Furthermore, the mixer core includes two double-balanced Gilbert units and a first balun circuit; the input ends of the two double-balanced Gilbert units are respectively connected to the I differential signal port and the Q differential signal port of the orthogonal signal generator; and the output ends of the two double-balanced Gilbert units are both connected to the input ends of the first balun circuit.

[0011] Furthermore, the orthogonal signal generator includes a 90° bridge based on a transmission line and two second balun circuits. The orthogonal signal generator is used to generate an I-channel differential signal and a Q-channel differential signal according to the input RF signal. The two output ends of the orthogonal signal generator are respectively connected to a second balun circuit. The second balun circuit is used to generate four orthogonal signals according to the I-channel differential signal or the Q-channel differential signal.

[0012] Furthermore, the reconfigurable matching network includes a first inductor, a second inductor and a variable capacitor; one end of the first inductor is connected to the output end of the mixer core, and the other end is grounded; one end of the second inductor is connected to the output end of the mixer core, and the other end is connected to a switching tube; the switching tube also includes a ground end and a control input end; one end of the variable capacitor is electrically connected to the input end of the second inductor, and the other end is electrically connected to the input end of the output buffer amplifier.

[0013] Furthermore, when a low-level control signal is input to the switch tube, the switch tube is disconnected, and the second inductor is in an open-circuit state;

[0014] When a high-level control signal is input to the switch tube, the switch tube is turned on, and the second inductor is in a conduction state. At this time, the first inductor and the second inductor form an equivalent inductor.

[0015] Furthermore, the digital-to-analog converter adopts a 10-bit current steering type, wherein the upper 4 bits adopt temperature decoding and the lower 6 bits adopt binary decoding.

[0016] Furthermore, the switching low-pass filter includes:

[0017] Low-pass filter, composed of capacitors and resistors;

[0018] a first transistor, an output end of which is electrically connected to the input end of the low-pass filter, and configured to convert the current signal output by the DAC into a voltage signal;

[0019] a transmission gate circuit, comprising a second transistor and a third transistor, wherein the bases of the second transistor and the third transistor receive a first switching signal and a second switching signal respectively; the first switching signal and the second switching signal have opposite control logics;

[0020] The input end and the output end of the transmission gate circuit are electrically connected to the two ends of the resistor of the low-pass filter respectively.

[0021] Furthermore, when the first switching signal is at a high level, the switching low-pass filter is in a communication state; and when the second switching signal is at a low level, the switching low-pass filter is in a phase-shift state.

[0022] Furthermore, when the multifunctional mixer structure is in a phase-shifted state, the phase of the output signal is:

[0023]

[0024] Among them, RF out represents the RF signal output of the multifunctional mixer structure, θ(RF out ) represents the phase of the output, Q Path Indicates Q-channel RF signal, I Path Indicates I-channel RF signal, and RF out =I Path +Q Path j.

[0025] Furthermore, when the multifunctional mixer structure is in the communication state, the output signal is:

[0026] RF MIXER.out =cos(ω LO t)×BB I cos(ω BB t)+sin(ω LO t)×BB Q cos(ω BB t);

[0027] Among them, RFMIXER.out represents the mixed signal output of the multifunctional mixer structure, LO represents the local oscillator signal, ω LO represents the local oscillator angular frequency, t represents the time variable, BB I Indicates the baseband signal of channel I, BB Q represents the Q-path baseband signal, ω BB Indicates the baseband signal angular frequency.

[0028] The multifunctional mixer structure with integrated communication and phase shifting of the present invention has at least the following beneficial effects: the proposed circuit can simultaneously realize the functions of communication and phase shifting, and utilizes a reconfigurable matching network structure to solve the problem of inconsistent output impedance of the circuit in the communication and phase shift states, thereby reducing impedance mismatch and improving gain. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0030] Figure 1 It is a structural diagram of an embodiment of a multifunctional mixer structure with integrated communication phase shifting according to the present invention.

[0031] Figure 2 FIG. 1 is a circuit diagram of an embodiment of a mixer core according to the present invention.

[0032] Figure 3 FIG. 4 is a circuit diagram of an embodiment of an orthogonal signal generator according to the present invention.

[0033] Figure 4 FIG. 4 is a circuit diagram of an embodiment of a reconfigurable matching network according to the present invention.

[0034] Figure 5 FIG. 4 is a circuit diagram of a digital-to-analog converter according to an embodiment of the present invention.

[0035] Figure 6 FIG. 4 is a circuit diagram of an embodiment of a switching low-pass filter according to the present invention.

[0036] Figure 7 FIG. 1 is a circuit diagram of a buffer amplifier according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The present invention will be further described below with reference to the accompanying drawings.

[0038] See also Figure 1 , is a schematic diagram of a structure of an embodiment of a multifunctional mixer structure with integrated communication phase shifting according to the present invention. The multifunctional mixer structure may include a mixer core for adjusting phase or mixing modulation.

[0039] In some embodiments, the mixer core may include two double-balanced Gilbert cells and a first balun circuit, see Figure 2 M5, M6, M7, and M8 form a Gilbert cell, M9, M10, M11, and M12 form another Gilbert cell, and transistors M1, M2, M3, and M4 together form a tail current source portion for converting a voltage signal into a current signal. Furthermore, by connecting the inputs of the two double-balanced Gilbert cells to the I differential signal port and the Q differential signal port of the quadrature signal generator, respectively; and connecting the outputs of the two double-balanced Gilbert cells to the inputs of the first balun circuit, the output of the mixer core is converted from a differential signal to a single-ended signal output through the first balun circuit, thereby achieving vector synthesis of the output signals.

[0040] The multifunctional mixer structure may further include:

[0041] An orthogonal signal generator has an output terminal electrically connected to the first input terminal of the mixer core and is used to generate differential orthogonal signals.

[0042] See also Figure 3 In some embodiments, the orthogonal signal generator may specifically include a 90° bridge based on a transmission line and two second balun circuits. The orthogonal signal generator is used to generate an I-channel differential signal and a Q-channel differential signal based on the input RF signal. The two output ends of the orthogonal signal generator are respectively connected to a second balun circuit, and the second balun circuit is used to generate four orthogonal signals based on the I-channel differential signal or the Q-channel differential signal. The input signal can generate I-channel and Q-channel signals through the 90° bridge based on the transmission line. At this time, the I-channel and Q-channel signals have equal amplitudes and a phase difference of 90°. The I-channel and Q-channel signals respectively pass through the balun to generate four orthogonal signals, I_P, I_N, Q_P, and Q_N. At the same time, each port of the orthogonal signal generator can be matched to 50Ω.

[0043] A reconfigurable matching network has an input end connected to the mixing output end of the mixer core and an output end connected to an output buffer amplifier. The output buffer amplifier is used to adjust the output impedance of the mixer core in a communication state.

[0044] See also Figure 4The reconfigurable matching network includes a first inductor, a second inductor, and a variable capacitor. One end of the first inductor is connected to the output of the mixer core, and the other end is grounded. One end of the second inductor is connected to the output of the mixer core, and the other end is connected to a switch. The switch also includes a ground terminal and a control input terminal. One end of the variable capacitor is electrically connected to the input of the second inductor, and the other end is electrically connected to the input of the output buffer amplifier. Specifically, the reconfigurable matching network consists of a first inductor L1, a second inductor LM1, and a voltage-controlled variable capacitor CV1. The first inductor LM1 is connected in series with a switch MC1 connected to ground. The control signal SC1 that controls the switch determines whether the switch MC1 is disconnected, thereby determining whether the second inductor LM1 is open-circuited.

[0045] In some embodiments, when a low-level control signal is input to the switch tube MC1, the switch tube MC1 is disconnected and the second inductor LM1 is in an open-circuit state; at this time, the multifunctional mixer structure is in a phase-shifted state, and the first inductor L1 and the variable capacitor CV1 form a first-order LC matching network, thereby matching the output impedance of the mixer core to the conjugate value of the input impedance of the output buffer amplifier.

[0046] When a high-level control signal is input to the switch MC1, the switch MC1 is turned on, and the second inductor LM1 is in a conducting state. At this time, the first inductor L1 and the second inductor LM1 form an equivalent inductor. This equivalent inductor. At this time, the multifunctional mixer structure is in a communication state. Since the output of the multifunctional mixer is a high impedance and the input impedance of the output buffer amplifier is relatively small, a smaller parallel inductor value is required. At this time, the control bit SC1 is at a high level, the switch MC1 is turned on, and the inductor LM1 participates in the matching network. The first inductor L1 and the second inductor LM1 together form an equivalent inductor Ltot, whose value is:

[0047]

[0048] At this time, by adjusting the inductance of the second inductor LM1 and the capacitance of the variable capacitor CV1, the equivalent inductor Ltot and the variable capacitor CV1 form a first-order LC matching network to match the output impedance of the mixer core to the conjugate value of the input impedance of the output buffer amplifier.

[0049] In some embodiments, see Figure 7 The output buffer amplifier adopts the structure of a common source amplifier plus a neutralizing capacitor, which stabilizes the amplifier and increases the maximum available gain of the amplifier.

[0050] The digital-to-analog converter is used to convert the input I-channel digital baseband signal and Q-channel digital baseband signal into analog signals.

[0051] See also Figure 5 This DAC uses a 10-bit current-steering type, with the upper four bits using temperature decoding and the lower six bits using binary decoding. Specifically, this DAC controls the on / off switching of the current mirror based on the input data D<9:0>, thereby adjusting the output current and implementing a DAC function. The upper four bits D<9:6> are converted by the decoding circuit into a 15-bit temperature code, with each thermometer code having a weight of 64. The lower six bits D<5:0> are directly controlled by a binary code, with weights of 32, 16, 8, 4, 2, and 1, respectively.

[0052] The switching low-pass filter has an output terminal electrically connected to the second input terminal of the mixer core, and an input terminal electrically connected to the output terminal of the digital-to-analog converter.

[0053] See also Figure 6 , the switching low-pass filter may include:

[0054] Low-pass filter, composed of capacitors and resistors;

[0055] a first transistor, an output end of which is electrically connected to the input end of the low-pass filter, and configured to convert the current signal output by the DAC into a voltage signal;

[0056] a transmission gate circuit, comprising a second transistor and a third transistor, wherein the bases of the second transistor and the third transistor receive a first switching signal and a second switching signal respectively; the first switching signal and the second switching signal have opposite control logics;

[0057] The input end and the output end of the transmission gate circuit are electrically connected to the two ends of the resistor of the low-pass filter respectively.

[0058] The first transistor MN1 converts the current signal output by the DAC into a voltage signal. The second transistor MN2 and the third transistor MP2 form a transmission gate. The first switch signal SW1 and the second switch signal SW1N are a pair of opposite logic control signals: when the first switch signal SW1 is high, the second switch signal SW1N is low; when the first switch signal SW1 is low, the second switch signal SW1N is high. Resistor R1 and capacitor C1 form a low-pass filter. The function of the switching low-pass filter is determined by switching the first switch signal SW1: when in the communication state, the first switch signal SW1 is high; when in the phase-shift state, the first switch signal SW1 is low.

[0059] In summary, the basic principles of this solution are:

[0060] This multifunctional mixer structure consists of an orthogonal signal generator, a mixer core, a reconfigurable matching network, a switched low-pass filter, and a digital-to-analog converter. It can perform both communication and phase-shifting functions. The reconfigurable matching network and switched low-pass filter can switch between these two operating states, and the baseband signal also differs between the two operating states.

[0061] When the multifunctional mixer structure operates in the phase-shifted state, the input RF signal RFIN is generated by a quadrature signal generator into differential I and Q signals I_P, I_N, Q_P, and Q_N. These differential and quadrature signals I_P, I_N, Q_P, and Q_N serve as the inputs to the mixer core. In the phase-shifted state, the I and Q baseband signals correspond to the code values of the phase-shifted state. After passing through DAC1 and DAC2, the I and Q baseband signals generate DC signals IDC and QDC, respectively. In the phase-shifted state, the switched low-pass filters are in a low-pass state, filtering out clock signals fed through the DACs. After passing through the switched low-pass filters in the phase-shifted state, the DC signals IDC and QDC serve as tail current sources for the multifunctional mixer core. The mixer exhibits different gains under different tail currents. By controlling the code values of the I and Q baseband signals, the magnitude of the DC signals IDC and QDC can be varied, thereby adjusting the small-signal gain of the I and Q mixers and the amplitude of the RF output signals. Finally, the I and Q RF signals are vector synthesized RF out =I Path +Q Path j, the phase of the output signal of the multifunctional mixer core is:

[0062]

[0063] Among them, RF out represents the RF signal output of the multifunctional mixer structure, θ(RF out ) represents the phase of the output, Q Path Indicates Q-channel RF signal, I Path Indicates RF signal channel I. At this point, the multifunctional mixer core implements the phase shift function.

[0064] When the multifunctional mixer structure is working in the communication state, the input local oscillator (LO) signal is used to generate the differential signals I_P, I_N, Q_P, and Q_N of the I and Q paths through the orthogonal signal generator. The generated differential orthogonal signals I_P, I_N, Q_P, and Q_N serve as the input of the mixer core. In the communication state, the I and Q path baseband (BB) signals use the modulation signal for communication. The I path baseband signal is I DC +BB Icos(ω BB t), Q road baseband signal is Q DC +BB Q sin(ω BB t), where ω BB t is the angular frequency of the baseband signal, BB I and BB Q Carries the amplitude and phase information of the baseband signal. In addition, I DC =Q DC .

[0065] In the communication state, the switch type low pass filter is in the direct pass state, and the baseband signal I DC +BB I cos(ω BB t) and Q road baseband signal Q DC +BB Q sin(ω BB t) After passing through the switched low-pass filter in the communication state, it serves as the tail current source of the multi-function mixer core. After that, the mixer core mixes and modulates the LO signal and the baseband BB signal. The final output signal is:

[0066] RF MIXER.out =cos(ω LO t)×BB I cos(ω BB t)+sin(ω LO t)×BB Q cos(ω BB t);

[0067] Among them, RF MIXER.out represents the mixed signal output of the multifunctional mixer structure, LO represents the local oscillator signal, ω LO represents the local oscillator angular frequency, t represents the time variable, BB I Indicates the baseband signal of channel I, BB Q represents the Q-path baseband signal, ω BB Indicates the baseband signal angular frequency.

[0068] Thanks to I DC =Q DC , the signal after the mixer core output has no feedthrough of the local oscillator signal, which improves the linearity of the overall circuit.

[0069] At this time, the reconfigurable matching network structure is in the communication state. The reconfigurable matching network structure matches the output impedance of the mixer core in the communication state to the input conjugate matching impedance value of the output buffer amplifier, reducing the loss caused by reflection and improving the gain.

[0070] The circuit proposed in the present invention can realize the functions of communication and phase shifting simultaneously, and uses a reconfigurable matching network structure to solve the problem of inconsistent output impedance of the circuit in the communication and phase shifting states, reduce impedance mismatch and improve gain.

[0071] The above description merely expresses the preferred embodiments of the present invention, and its description is relatively specific and detailed, but it should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art may make a number of variations and improvements without departing from the concept of the present invention, and these variations and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent of the present invention shall be based on the appended claims.

Claims

1. A multifunctional mixer structure with integrated communication phase shifting, including a mixer core for adjusting phase or mixing modulation, characterized in that: Also includes: an orthogonal signal generator, an output end of which is electrically connected to the first input end of the mixer core, for generating differential orthogonal signals; a reconfigurable matching network, wherein an input end of the reconfigurable matching network is connected to a mixing output end of the mixer core, and an output end of the reconfigurable matching network is connected to an output buffer amplifier, wherein the output buffer amplifier is used to adjust the output impedance of the mixer core in a communication state; A digital-to-analog converter, used for converting the input I-channel digital baseband signal and Q-channel digital baseband signal into analog signals; The switching low-pass filter has an output terminal electrically connected to the second input terminal of the mixer core, and an input terminal electrically connected to the output terminal of the digital-to-analog converter.

2. The multifunctional mixer structure with integrated communication phase shifting according to claim 1, characterized in that: The mixer core includes two double-balanced Gilbert units and a first balun circuit; the input ends of the two double-balanced Gilbert units are respectively connected to the I differential signal port and the Q differential signal port of the orthogonal signal generator; the output ends of the two double-balanced Gilbert units are both connected to the input ends of the first balun circuit.

3. The multifunctional mixer structure with integrated communication phase shifting according to claim 1, characterized in that: The orthogonal signal generator includes a 90° bridge based on a transmission line and two second balun circuits. The orthogonal signal generator is used to generate an I-channel differential signal and a Q-channel differential signal according to the input radio frequency signal. The two output ends of the orthogonal signal generator are respectively connected to a second balun circuit. The second balun circuit is used to generate four orthogonal signals according to the I-channel differential signal or the Q-channel differential signal.

4. The multifunctional mixer structure with integrated communication phase shifting according to claim 1, characterized in that: The reconfigurable matching network includes a first inductor, a second inductor and a variable capacitor; one end of the first inductor is connected to the output end of the mixer core, and the other end is grounded; one end of the second inductor is connected to the output end of the mixer core, and the other end is connected to a switching tube; the switching tube also includes a ground terminal and a control input terminal; one end of the variable capacitor is electrically connected to the input end of the second inductor, and the other end is electrically connected to the input end of the output buffer amplifier.

5. The multifunctional mixer structure with integrated communication phase shifting as claimed in claim 4, characterized in that: When a low-level control signal is input to the switch tube, the switch tube is disconnected, and the second inductor is in an open-circuit state; When a high-level control signal is input to the switch tube, the switch tube is turned on, and the second inductor is in a conduction state. At this time, the first inductor and the second inductor form an equivalent inductor.

6. The multifunctional mixer structure with integrated communication phase shifting according to claim 1, characterized in that: The digital-to-analog converter adopts a 10-bit current steering type, wherein the upper 4 bits adopt temperature decoding and the lower 6 bits adopt binary decoding.

7. The multifunctional mixer structure with integrated communication phase shifting according to claim 1, characterized in that: The switching low-pass filter comprises: Low-pass filter, composed of capacitors and resistors; a first transistor, an output end of which is electrically connected to the input end of the low-pass filter, and configured to convert the current signal output by the DAC into a voltage signal; a transmission gate circuit, comprising a second transistor and a third transistor, wherein the bases of the second transistor and the third transistor receive a first switching signal and a second switching signal respectively; the first switching signal and the second switching signal have opposite control logics; The input end and the output end of the transmission gate circuit are electrically connected to the two ends of the resistor of the low-pass filter respectively.

8. The multifunctional mixer structure with integrated communication phase shifting as claimed in claim 7, characterized in that: When the first switching signal is at a high level, the switching low-pass filter is in a communication state; when the second switching signal is at a low level, the switching low-pass filter is in a phase-shift state.

9. The multifunctional mixer structure with integrated communication phase shifting according to claim 1, characterized in that: When the multifunctional mixer structure is in a phase-shift state, the phase of the output signal is: Among them, RF out represents the RF signal output of the multifunctional mixer structure, θ(RF out ) represents the phase of the output, Q Path Indicates Q-channel RF signal, I Path Indicates I-channel RF signal, and RF out =I Path +Q Path j.

10. The multifunctional mixer structure with integrated communication phase shifting according to claim 1, characterized in that: When the multifunctional mixer structure is in the communication state, the output signal is: RF MIXER.out =cos(ω) LO t)×BB I cos(ω BB t)+sin(ω LO t)×BB Q cos(ω BB t); Among them, RF MIXER.out represents the mixed signal output of the multifunctional mixer structure, LO represents the local oscillator signal, ω LO represents the local oscillator angular frequency, t represents the time variable, BB I Indicates the baseband signal of channel I, BB Q represents the Q-path baseband signal, ω BB Indicates the baseband signal angular frequency.

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