An ultra-wideband dual-mode mixer circuit with on-chip balun

Abstract

This application relates to an ultra-wideband dual-mode mixer circuit with an on-chip balun. The circuit includes: an LO port of a local oscillator differential balun unit connected to the signal output from the local oscillator source in a vector network analysis (VNA) system; an RF port of a mixer unit connected to the test signal preprocessed by the VNA system; an output port of the local oscillator differential balun unit connected to the local oscillator input port of the mixer unit; and an output port of the mixer unit connected to the input port of an intermediate frequency (IF) amplifier unit. The local oscillator signal in the VNA system is processed by the local oscillator differential balun unit to obtain two local oscillator differential signals. The high-frequency test signal preprocessed by the VNA system is input through the RF port of the mixer unit to obtain two radio frequency (RF) differential signals. The two RF differential signals are mixed with the two local oscillator differential signals to obtain the desired IF signal. The IF signal is finally amplified by the IF amplifier unit and output from the output port of the IF amplifier unit, thus solving the problems of low integration, large size, and poor isolation in ultra-wideband mixers.

Description

Technical Field

[0001] This application relates to the field of monolithic microwave integrated circuit technology, and in particular to an ultrawideband dual-mode mixer circuit with an on-chip balun. Background Technology

[0002] Mixer chips are the core chips of microwave measurement instruments, and they are particularly crucial in high-end microwave test instruments that use broadband and high-frequency signals. For example, a broadband mixer chip is the most critical component in the frequency conversion path of a vector network analyzer. Its function is to down-convert the received high-frequency microwave signal to a lower-frequency intermediate frequency signal using nonlinear devices, so as to facilitate subsequent digital processing of the signal.

[0003] With the development of various microwave technologies such as wireless communication and radar, their testing requirements have placed demands on high-end vector network analyzers (VNAs) for wider bandwidth, higher testing accuracy, and smaller size. This also determines the performance indicators of the ultra-wideband mixer chip in its core chips. Since the bandwidth of the ultra-wideband mixer chip directly limits the bandwidth of the entire VNA system, the mixer's bandwidth must be able to cover 10MHz to millimeter waves and even higher frequencies, just like the VNA itself. The LO-RF isolation of the mixer directly affects the testing accuracy of the VNA, so its LO-RF isolation must be greater than 40dB. Considering the consistency and size of the VNA frequency conversion module, it is desirable to integrate a balun on the mixer chip. In addition, to reduce the complexity and design difficulty of the VNA local oscillator, the mixer must be able to operate in dual mode, i.e., it can operate on the fundamental frequency at low frequencies and perform third harmonic mixing at high frequencies.

[0004] To address this application requirement, current ultra-wideband mixers suffer from the following problems: First, conventional ultra-wideband mixer chips typically operate at frequencies limited to a few octaves, making it difficult to cover frequencies from millimeter and submillimeter waves up to 10MHz. Second, even if some chips can operate from 10MHz, they lack integrated three-port ultra-wideband baluns. External baluns, due to their inability to share bias circuitry with the mixer, require an ultra-wideband DC blocking capacitor between them, resulting in low module integration, large size, and reduced consistency of the frequency converter module. Third, conventional ultra-wideband mixers also struggle to achieve a LO-RF isolation greater than 40dB across the entire frequency band.

[0005] Therefore, current ultrawideband mixers suffer from problems such as low integration, large size, and poor isolation. Summary of the Invention

[0006] Therefore, it is necessary to provide an ultra-wideband dual-mode mixer circuit with an on-chip balun that can solve the problems of low integration, large size and poor isolation of ultra-wideband mixers.

[0007] An ultrawideband dual-mode mixer circuit with an on-chip balun, the circuit comprising: a local oscillator differential balun unit, a mixer unit with an RF differential balun, and an intermediate frequency amplifier unit; The LO port of the local oscillator differential balun unit is connected to the signal output from the local oscillator source in the vector network analysis (VNA) system. The RF port of the mixer unit is connected to the signal to be measured after VNA preprocessing. The output port of the local oscillator differential balun unit is connected to the local oscillator input port of the mixer unit. The output port of the mixer unit is connected to the input port of the intermediate frequency amplifier unit. The local oscillator signal in the vector network analyzer (VNA) is processed by the local oscillator differential balun unit to obtain two local oscillator differential signals. The high-frequency test signal, after preprocessing by the VNA, is input to the RF port of the mixer unit to obtain two radio frequency (RF) differential signals. The two RF differential signals are mixed with the two local oscillator differential signals to obtain the required intermediate frequency (IF) signal. The IF signal is finally amplified by the IF amplifier unit and output from the output port of the IF amplifier unit.

[0008] In one embodiment, the local oscillator differential balun unit includes: a first emitter follower, a first-stage differential amplifier circuit, a second emitter follower, a second-stage differential amplifier circuit, and a third emitter follower; The input terminal of the first emitter follower is the LO port of the local oscillator differential balun unit. The output terminal of the first emitter follower is connected to the input terminal of the first stage differential amplifier circuit. The output terminal of the first stage differential amplifier circuit is connected to the input terminal of the second emitter follower. The output terminal of the second emitter follower is connected to the input terminal of the second stage differential amplifier circuit. The output terminal of the second stage differential amplifier circuit is connected to the input terminal of the third emitter follower. The output terminal of the third emitter follower is the output port of the local oscillator differential balun unit.

[0009] In one embodiment, the first emitter follower includes: a first transistor, a second transistor, a first resistor, a second resistor, a fourteenth resistor, and a fifteenth resistor; The base of the first transistor serves as the input terminal of the first emitter follower. The base of the first transistor is connected to one end of the first resistor, and the emitter of the first transistor is connected to one end of the fourteenth resistor. The base of the second transistor is connected to one end of the second resistor, and the emitter of the second transistor is connected to one end of the fifteenth resistor. The collectors of the first and second transistors are grounded, and the other ends of the first and second resistors are grounded. The other ends of the fourteenth and fifteenth resistors are connected to a power supply. The emitters of the first and second transistors serve as the output terminals of the first emitter follower.

[0010] In one embodiment, the first-stage differential amplifier circuit includes a third transistor, a fourth transistor, a third resistor, a fourth resistor, and a sixteenth resistor; The bases of the third and fourth transistors serve as the input terminals of the first-stage differential amplifier circuit. The emitters of the third and fourth transistors are connected to one end of the sixteenth resistor. The collector of the third transistor is connected to one end of the third resistor, and the collector of the fourth transistor is connected to one end of the fourth resistor. The other ends of the third and fourth resistors are grounded, and the other end of the sixteenth resistor is connected to the power supply. The collectors of the third and fourth transistors serve as the output terminals of the first-stage differential amplifier circuit.

[0011] In one embodiment, the second emitter follower includes: a fifth transistor, a sixth transistor, a seventeenth resistor, and an eighteenth resistor; The bases of the fifth and sixth transistors serve as the input terminals of the second emitter follower. The emitter of the fifth transistor is connected to one end of the seventeenth resistor, and the emitter of the sixth transistor is connected to one end of the eighteenth resistor. The collectors of the fifth and sixth transistors are grounded, and the other ends of the seventeenth and eighteenth resistors are connected to a power supply. The emitters of the fifth and sixth transistors serve as the output terminals of the second emitter follower.

[0012] In one embodiment, the second-stage differential amplifier circuit includes: a seventh transistor, an eighth transistor, a fifth resistor, a sixth resistor, and a nineteenth resistor; The bases of the seventh and eighth transistors serve as the input terminals of the second-stage differential amplifier circuit. The emitters of the seventh and eighth transistors are connected to one end of the nineteenth resistor. The collector of the seventh transistor is connected to one end of the fifth resistor, and the collector of the eighth transistor is connected to one end of the sixth resistor. The other ends of the fifth and sixth resistors are grounded, and the other end of the nineteenth resistor is connected to the power supply. The collectors of the seventh and eighth transistors serve as the output terminals of the second-stage differential amplifier circuit.

[0013] In one embodiment, the third emitter follower includes a ninth transistor, a tenth transistor, a twentieth resistor, and a twenty-first resistor; The bases of the ninth and tenth transistors serve as the input terminals of the third emitter follower. The emitter of the ninth transistor is connected to one end of the twentieth resistor, and the emitter of the tenth transistor is connected to one end of the twentieth resistor. The collectors of the ninth and tenth transistors are grounded, and the other ends of the twentieth and twentieth resistors are connected to a power supply. The emitters of the ninth and tenth transistors serve as the output terminals of the third emitter follower.

[0014] In one embodiment, the mixer unit includes an input emitter follower, an RF transconductance amplifier stage, and an LO switching stage; The input terminal of the input emitter follower serves as the RF port of the mixer unit. The output terminal of the input emitter follower is connected to the input terminal of the RF transconductance amplifier stage. The output terminal of the RF transconductance amplifier stage is connected to the input terminal of the LO switch stage. The output terminal of the LO switch stage serves as the output port of the mixer unit. The local oscillator input terminal of the LO switch stage serves as the local oscillator input port of the mixer unit.

[0015] In one embodiment, the input emitter follower includes a seventeenth transistor, an eighteenth transistor, a ninth resistor, and a tenth resistor; The base of the seventeenth transistor serves as the input terminal of the input emitter follower. The base of the seventeenth transistor is connected to one end of the tenth resistor. The emitter of the seventeenth transistor is connected to one end of the twenty-fourth resistor. The base of the eighteenth transistor is connected to one end of the ninth resistor. The emitter of the eighteenth transistor is connected to one end of the twenty-third resistor. The collectors of the seventeenth and eighteenth transistors are grounded. The other ends of the ninth and tenth resistors are grounded. The other ends of the twenty-third and twenty-fourth resistors are connected to the power supply. The emitters of the seventeenth and eighteenth transistors serve as the output terminals of the input emitter follower.

[0016] In one embodiment, the RF transconductance amplifier stage includes a fifteenth transistor, a sixteenth transistor, an eleventh resistor, a twelfth resistor, and a twenty-second resistor; The bases of the fifteenth and sixteenth transistors serve as the input terminals of the RF transconductance amplifier stage. The emitter of the fifteenth transistor is connected to one end of the eleventh resistor, and the emitter of the sixteenth transistor is connected to one end of the twelfth resistor. The other ends of the eleventh and twelfth resistors are connected to one end of the twenty-second resistor, and the other end of the twenty-second resistor is connected to the power supply. The collectors of the fifteenth and sixteenth transistors serve as the output terminals of the RF transconductance amplifier stage.

[0017] In one embodiment, the LO switching stage includes an eleventh transistor, a twelfth transistor, a thirteenth transistor, a fourteenth transistor, a seventh resistor, and an eighth resistor; The emitters of the eleventh, twelfth, thirteenth, and fourteenth transistors serve as the input terminals of the LO switching stage. The bases of the eleventh, twelfth, thirteenth, and fourteenth transistors serve as the local oscillator input terminals of the LO switching stage. The collectors of the eleventh and thirteenth transistors are connected to one end of the seventh resistor. The collectors of the twelfth and fourteenth transistors are connected to one end of the eighth resistor. The collectors of the twelfth and fourteenth transistors, after being connected, serve as the output terminals of the LO switching stage. The other ends of the seventh and eighth resistors are grounded.

[0018] In one embodiment, the intermediate frequency amplification unit includes a nineteenth transistor, a thirteenth resistor, and a twenty-fifth resistor; The base of the nineteenth transistor serves as the input port of the intermediate frequency amplifier unit. The collector of the nineteenth transistor is grounded. The emitter of the nineteenth transistor is connected to one end of the thirteenth resistor and one end of the twenty-fifth resistor. The other end of the thirteenth resistor is the output port of the intermediate frequency amplifier unit, and the other end of the twenty-fifth resistor is connected to the power supply.

[0019] The aforementioned ultra-wideband dual-mode mixer circuit with on-chip balun connects the signal output from the local oscillator source in the vector network analysis (VNA) to the LO port of the local oscillator differential balun unit. The RF port of the mixer unit connects to the test signal preprocessed by the VNA. The output port of the local oscillator differential balun unit is connected to the local oscillator input port of the mixer unit, and the output port of the mixer unit is connected to the input port of the intermediate frequency (IF) amplifier unit. The local oscillator signal in the VNA passes through the local oscillator differential balun unit to obtain two local oscillator differential signals. The high-frequency test signal preprocessed by the VNA is input through the RF port of the mixer unit to obtain two radio frequency (RF) differential signals. These two RF differential signals are mixed with the two local oscillator differential signals to obtain the desired IF signal. The IF signal is then... After amplification by the intermediate frequency (IF) amplifier, the signal is output from the IF amplifier's output port. This allows the operating frequency of the ultra-wideband mixer to be reduced to DC while integrating an on-chip ultra-wideband balun and an IF amplifier. The local oscillator differential balun unit uses a two-stage differential structure to perform secondary shaping of the local oscillator signal, thereby further improving the balun's imbalance and enhancing the LO-RF isolation of the ultra-wideband dual-mode mixer circuit with an on-chip balun. The mixer unit, employing a double-balanced structure, only suppresses even harmonics, and the ultra-wideband resistive matching makes the bandwidth far exceed three octaves. The mixer unit can be used for fundamental and third harmonic mixing simultaneously, thus solving the problems of low integration, large size, and poor isolation in ultra-wideband mixers. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the ultrawideband dual-mode mixer circuit with on-chip balun of this application; Figure 2 This is a schematic diagram of the topology of the local oscillator differential balun unit in this application; Figure 3 This is a schematic diagram of the topology of the mixer unit with radio frequency differential balun in this application; Figure 4 This is a schematic diagram of the test results of the frequency conversion loss in the fundamental frequency mixing mode of the embodiments of this application; Figure 5 This is a schematic diagram of the test results of the frequency conversion loss in the third harmonic mixing mode according to an embodiment of this application; Figure 6 This is a schematic diagram of the test results of LO-RF / LO-IF isolation in the fundamental frequency mixing mode of this application embodiment; Figure 7 This is a schematic diagram of the test results of RF-LO / RF-IF isolation in the fundamental frequency mixing mode of this application embodiment; Figure 8 This is a schematic diagram of the test results of RF-LO / RF-IF isolation in the third harmonic mixing mode of this application embodiment. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] In related fields, the role of an ultra-wideband (UWB) mixer chip in vector network analyzers (VNA) is to down-convert received high-frequency microwave signals to lower-frequency intermediate frequency (IF) signals using nonlinear devices, facilitating subsequent digital processing. The circuit design of the UWB mixer chip comprehensively considers factors such as bandwidth, conversion loss, isolation, and linearity. To improve measurement accuracy, it is necessary to reduce crosstalk between ports; therefore, the mixer is required to have high port isolation. The UWB mixer chip is fabricated using the UWB dual-mode mixer circuit with an on-chip balun as described in this application, employing a dual-balanced structure. The RF and LO ports of this UWB dual-mode mixer circuit are differential inputs, and for ease of use, the UWB dual-mode mixer circuit also integrates an UWB LO balun.

[0023] In one embodiment, such as Figure 1 As shown, an ultra-wideband dual-mode mixer circuit with an on-chip balun is provided. The circuit includes: a local oscillator differential balun unit 10, a mixer unit 20 with an RF differential balun, and an intermediate frequency amplifier unit 30.

[0024] The LO port LOIN of the local oscillator differential balun unit 10 is connected to the signal output from the local oscillator source in the vector network analysis (VNA). The RF port RFIN of the mixer unit 20 is connected to the signal to be measured after VNA preprocessing. The output port of the local oscillator differential balun unit 10 is connected to the local oscillator input port of the mixer unit 20. The output port of the mixer unit 20 is connected to the input port of the intermediate frequency amplifier unit 30.

[0025] The local oscillator signal in the vector network analyzer (VNA) is processed by the local oscillator differential balun unit 10 to obtain two local oscillator differential signals. The high-frequency test signal, after preprocessing by the VNA, is input to the RF port RFIN of the mixer unit 20 to obtain two radio frequency (RF) differential signals. The two RF differential signals are mixed with the two local oscillator differential signals to obtain the required intermediate frequency (IF) signal. The IF signal is finally amplified by the IF amplifier unit 30 and output from the output port IFOUT of the IF amplifier unit 30.

[0026] Among them, the two local oscillator differential signals are local oscillator signals with the same amplitude and a phase difference of 180 degrees.

[0027] Among them, the two radio frequency differential signals are radio frequency signals with the same amplitude but a phase difference of 180 degrees.

[0028] Among them, the ultra-wideband dual-mode mixer circuit with on-chip balun uses DC coupling technology to realize the local oscillator differential balun unit, the mixer unit with RF differential balun and the intermediate frequency amplifier unit. This avoids the use of ultra-wideband DC blocking capacitors that are difficult to implement on-chip between various functional circuits, which is conducive to greatly reducing the chip area and improving the system integration. At the same time, it can also extend the operating frequency of the ultra-wideband mixer to DC.

[0029] The aforementioned ultra-wideband dual-mode mixer circuit with on-chip balun can reduce the operating frequency of the ultra-wideband mixer to DC while integrating an on-chip ultra-wideband balun and intermediate frequency amplifier unit. The local oscillator differential balun unit uses a two-stage differential structure to perform secondary shaping of the local oscillator signal, thereby further improving the balun imbalance and enhancing the LO-RF isolation of the ultra-wideband dual-mode mixer circuit with on-chip balun. The mixer unit with a double-balanced structure only suppresses even harmonics, and the ultra-wideband resistive matching makes the bandwidth far exceed three octaves. The mixer unit can be used for fundamental and third harmonic mixing simultaneously, thus solving the problems of low integration, large size, and poor isolation of ultra-wideband mixers.

[0030] like Figure 1 and Figure 2 As shown, in one embodiment, the local oscillator differential balun unit 10 includes: a first emitter follower, a first-stage differential amplifier circuit, a second emitter follower, a second-stage differential amplifier circuit, and a third emitter follower; the input terminal of the first emitter follower is the LO port LOIN of the local oscillator differential balun unit 10, the output terminal of the first emitter follower is connected to the input terminal of the first-stage differential amplifier circuit, the output terminal of the first-stage differential amplifier circuit is connected to the input terminal of the second emitter follower, the output terminal of the second emitter follower is connected to the input terminal of the second-stage differential amplifier circuit, the output terminal of the second-stage differential amplifier circuit is connected to the input terminal of the third emitter follower, and the output terminal of the third emitter follower is the output port of the local oscillator differential balun unit 10.

[0031] The local oscillator differential balun unit 10 consists of two stages of differential amplification (i.e., the first stage differential amplification circuit and the second stage differential amplification circuit), which improves the gain and performs secondary waveform shaping, thereby further improving the imbalance of the active balun. Each stage of differential amplification is followed by an emitter follower cascade structure (i.e., the second emitter follower and the third emitter follower), which can reduce current mismatch and greatly improve the balance, thereby improving the LO-RF isolation of the ultra-wideband dual-mode mixer circuit with on-chip balun.

[0032] like Figure 1 and Figure 2As shown, in one embodiment, the first emitter follower includes: a first transistor Q1, a second transistor Q2, a first resistor R1, a second resistor R2, a fourteenth resistor R14, and a fifteenth resistor R15; the base of the first transistor Q1 serves as the input terminal of the first emitter follower, the base of the first transistor Q1 is connected to one end of the first resistor R1, the emitter of the first transistor Q1 is connected to one end of the fourteenth resistor R14, the base of the second transistor Q2 is connected to one end of the second resistor R2, the emitter of the second transistor Q2 is connected to one end of the fifteenth resistor R15, the collectors of the first transistor Q1 and the second transistor Q2 are grounded, the other ends of the first resistor R1 and the second resistor R2 are grounded, the other ends of the fourteenth resistor R14 and the fifteenth resistor R15 are connected to the power supply VEE, and the emitters of the first transistor Q1 and the second transistor Q2 serve as the output terminals of the first emitter follower.

[0033] It should be understood that the first emitter follower is the emitter follower of the local oscillator signal terminal. The first emitter follower has a high input resistance. Using the first emitter follower as the input stage of the local oscillator differential balun unit results in a small current being drawn from the signal source, thus having a small impact on the signal source. This can reduce the impact of the impedance of the preamplifier circuit on the ultra-wideband dual-mode mixer circuit with on-chip balun.

[0034] like Figure 1 and Figure 2 As shown, in one embodiment, the first-stage differential amplifier circuit includes a third transistor Q3, a fourth transistor Q4, a third resistor R3, a fourth resistor R4, and a sixteenth resistor R16. The bases of the third transistor Q3 and the fourth transistor Q4 serve as the input terminals of the first-stage differential amplifier circuit. The emitters of the third transistor Q3 and the fourth transistor Q4 are connected to one end of the sixteenth resistor R16. The collector of the third transistor Q3 is connected to one end of the third resistor R3, and the collector of the fourth transistor Q4 is connected to one end of the fourth resistor R4. The other ends of the third resistor R3 and the fourth resistor R4 are grounded, and the other end of the sixteenth resistor R16 is connected to the power supply VEE. The collectors of the third transistor Q3 and the fourth transistor Q4 serve as the output terminals of the first-stage differential amplifier circuit.

[0035] The first-stage differential amplifier circuit, serving as the first-stage differential amplifier in the local oscillator differential balun unit, splits the input local oscillator signal into two equal-amplitude, inversely opposite signals. This first-stage differential amplifier circuit can convert the local oscillator signal input at the LO port into a dual-ended differential output signal, while simultaneously suppressing common-mode noise and signal jitter caused by external factors.

[0036] like Figure 1 and Figure 2 As shown, in one embodiment, the second emitter follower includes: a fifth transistor Q5, a sixth transistor Q6, a seventeenth resistor R17, and an eighteenth resistor R18; the bases of the fifth transistor Q5 and the sixth transistor Q6 serve as the input terminals of the second emitter follower; the emitter of the fifth transistor Q5 is connected to one end of the seventeenth resistor R17; the emitter of the sixth transistor Q6 is connected to one end of the eighteenth resistor R18; the collectors of the fifth transistor Q5 and the sixth transistor Q6 are grounded; the other ends of the seventeenth resistor R17 and the eighteenth resistor R18 are connected to the power supply VEE; and the emitters of the fifth transistor Q5 and the sixth transistor Q6 serve as the output terminals of the second emitter follower.

[0037] In this circuit, the second emitter follower serves as the emitter follower after the first-stage differential amplifier circuit. This structure, where a second emitter follower is connected after the first-stage differential amplifier circuit, reduces current mismatch and significantly improves the balance. Furthermore, the second emitter follower has a very low output resistance and strong load-driving capability, which is beneficial for impedance matching and interstage isolation between the first and second-stage differential amplifier circuits.

[0038] like Figure 1 and Figure 2 As shown, in one embodiment, the second-stage differential amplifier circuit includes: a seventh transistor Q7, an eighth transistor Q8, a fifth resistor R5, a sixth resistor R6, and a nineteenth resistor R19; the bases of the seventh transistor Q7 and the eighth transistor Q8 serve as the input terminals of the second-stage differential amplifier circuit; the emitters of the seventh transistor Q7 and the eighth transistor Q8 are connected to one end of the nineteenth resistor R19; the collector of the seventh transistor Q7 is connected to one end of the fifth resistor R5; the collector of the eighth transistor Q8 is connected to one end of the sixth resistor R6; the other ends of the fifth resistor R5 and the sixth resistor R6 are grounded; the other end of the nineteenth resistor R19 is connected to the power supply VEE; and the collectors of the seventh transistor Q7 and the eighth transistor Q8 serve as the output terminals of the second-stage differential amplifier circuit.

[0039] The second-stage differential amplifier circuit serves as the second-stage differential amplifier circuit in the local oscillator differential balun unit. The local oscillator differential balun unit uses two-stage differential amplifier circuits (i.e., the first-stage differential amplifier circuit and the second-stage differential amplifier circuit) cascaded to realize the active differential balun at the local oscillator end. This not only provides higher gain and reduces input power, but also shapes the input waveform, thereby further improving the imbalance of the local oscillator differential balun.

[0040] like Figure 1 and Figure 2As shown, in one embodiment, the third emitter follower includes a ninth transistor Q9, a tenth transistor Q10, a twentieth resistor R20, and a twenty-first resistor R21; the bases of the ninth transistor Q9 and the tenth transistor Q10 serve as the input terminals of the third emitter follower; the emitter of the ninth transistor Q9 is connected to one end of the twentieth resistor R20; the emitter of the tenth transistor Q10 is connected to one end of the twenty-first resistor R21; the collectors of the ninth transistor Q9 and the tenth transistor Q10 are grounded; the other ends of the twentieth resistor R20 and the twenty-first resistor R21 are connected to the power supply VEE; and the emitters of the ninth transistor Q9 and the tenth transistor Q10 serve as the output terminals of the third emitter follower.

[0041] Among them, the third emitter follower serves as the emitter follower of the second-stage differential amplifier circuit, and the emitter outputs of the ninth transistor Q9 and the tenth transistor Q10 are two equal-amplitude, opposite local oscillator signals, which serve as the input signals of the local oscillator input port of the mixer unit 20.

[0042] like Figure 1 and Figure 3 As shown, in one embodiment, the mixer unit 20 includes an input emitter follower, an RF transconductance amplifier stage, and an LO switch stage; the input terminal of the input emitter follower serves as the RF port RFIN of the mixer unit 20, the output terminal of the input emitter follower is connected to the input terminal of the RF transconductance amplifier stage, the output terminal of the RF transconductance amplifier stage is connected to the input terminal of the LO switch stage, the output terminal of the LO switch stage serves as the output port of the mixer unit 20, and the local oscillator input terminal of the LO switch stage serves as the local oscillator input port of the mixer unit 20.

[0043] Among them, the RF transconductance amplifier stage and LO switching stage in the mixer unit with RF differential balun constitute the Gilbert mixer structure (double balanced structure). Compared with single tube and single balanced structure, double balanced structure has better port isolation and clutter suppression.

[0044] like Figure 1 and Figure 3As shown, in one embodiment, the input emitter follower includes a seventeenth transistor Q17, an eighteenth transistor Q18, a ninth resistor R9, and a tenth resistor R10; the base of the seventeenth transistor Q17 serves as the input terminal of the input emitter follower, the base of the seventeenth transistor Q17 is connected to one end of the tenth resistor R10, the emitter of the seventeenth transistor Q17 is connected to one end of the twenty-fourth resistor R24, the base of the eighteenth transistor Q18 is connected to one end of the ninth resistor R9, the emitter of the eighteenth transistor Q18 is connected to one end of the twenty-third resistor R23, the collectors of the seventeenth transistor Q17 and the eighteenth transistor Q18 are grounded, the other ends of the ninth resistor R9 and the tenth resistor R10 are grounded, the other ends of the twenty-third resistor R23 and the twenty-fourth resistor R24 ​​are connected to the power supply VEE, and the emitters of the seventeenth transistor Q17 and the eighteenth transistor Q18 serve as the output terminals of the input emitter follower.

[0045] Among them, the input emitter follower has a high input resistance, draws a small current from the signal source, and has a small impact on the signal source. Therefore, using the input emitter follower as the input stage of the RF signal can reduce the impact of the preamplifier impedance on the ultra-wideband dual-mode mixer circuit with on-chip balun.

[0046] like Figure 1 and Figure 3 As shown, in one embodiment, the RF transconductance amplifier stage includes a fifteenth transistor Q15, a sixteenth transistor Q16, an eleventh resistor R11, a twelfth resistor R12, and a twenty-second resistor R22. The bases of the fifteenth transistor Q15 and the sixteenth transistor Q16 serve as the input terminals of the RF transconductance amplifier stage. The emitter of the fifteenth transistor Q15 is connected to one end of the eleventh resistor R11, and the emitter of the sixteenth transistor Q16 is connected to one end of the twelfth resistor R12. The other ends of the eleventh resistor R11 and the twelfth resistor R12 are connected to one end of the twenty-second resistor R22, and the other end of the twenty-second resistor R22 is connected to the power supply VEE. The collectors of the fifteenth transistor Q15 and the sixteenth transistor Q16 serve as the output terminals of the RF transconductance amplifier stage.

[0047] In this circuit, the bases of the fifteenth transistor Q15 and the sixteenth transistor Q16 are connected to the first node 1 and the second node 2, respectively. The emitters of both transistors are connected to the eleventh resistor R11 and the twelfth resistor R12, and then together connected to the twenty-second resistor R22. The eleventh and twelfth resistors R11 and R12 are primarily used for emitter degradation, which improves the linearity of the mixer circuit. The collectors of the fifteenth transistor Q15 and the sixteenth transistor Q16 are connected to the third node 3 and the fourth node 4, respectively. The fifteenth transistor Q15 and the sixteenth transistor Q16 share the LO switching current and employ a self-biased structure, eliminating the need for an additional bias circuit.

[0048] In this unit, the RF transconductance amplifier stage serves as the transconductance stage within the mixer unit 20. The RF excitation signal is input from the base of the transconductance stage, and the RF transconductance amplifier stage converts the RF voltage signal into an output signal in the form of a current source. Furthermore, the phase difference between the two output signals after passing through the differential amplifier of the transconductance stage is close to 180°. Therefore, the RF transconductance amplifier also functions as an RF balun, which also helps to simplify the circuit structure and reduce the chip size.

[0049] like Figure 1 and Figure 3 As shown, in one embodiment, the LO switching stage includes an eleventh transistor Q11, a twelfth transistor Q12, a thirteenth transistor Q13, a fourteenth transistor Q14, a seventh resistor R7, and an eighth resistor R8. The emitters of the eleventh transistor Q11, the twelfth transistor Q12, the thirteenth transistor Q13, and the fourteenth transistor Q14 serve as the input terminals of the LO switching stage. The bases of the eleventh transistor Q11, the twelfth transistor Q12, the thirteenth transistor Q13, and the fourteenth transistor Q14 serve as the local oscillator input terminals of the LO switching stage. The collectors of the eleventh transistor Q11 and the thirteenth transistor Q13 are connected to one end of the seventh resistor R7. The collectors of the twelfth transistor Q12 and the fourteenth transistor Q14 are connected to one end of the eighth resistor R8. The collectors of the twelfth transistor Q12 and the fourteenth transistor Q14, after being connected, serve as the output terminals of the LO switching stage. The other ends of the seventh resistor R7 and the eighth resistor R8 are grounded.

[0050] In this configuration, the bases of the eleventh transistor Q11 and the fourteenth transistor Q14 are connected to the emitter of the ninth transistor Q9, and the bases of the twelfth transistor Q12 and the thirteenth transistor Q13 are connected to the emitter of the tenth transistor Q10. These two transistors serve as the input ports for the local oscillator signal, and the local oscillator excitation LO is fed in from these ports in a differential signal manner. The emitters of the eleventh transistor Q11 and the twelfth transistor Q12 are connected to the third node 3, and the emitters of the thirteenth transistor Q13 and the fourteenth transistor Q14 are connected to the fourth node 4, respectively receiving the differential current signals output from the RF transconductance amplifier stage. The collectors of the eleventh transistor Q11 and the thirteenth transistor Q13 are connected to the fifth node 5, and the collectors of the twelfth transistor Q12 and the fourteenth transistor Q14 are connected to the sixth node 6 as the output terminals for the intermediate frequency signal obtained by mixing.

[0051] like Figure 1 As shown, in one embodiment, the intermediate frequency amplifier unit 30 includes a nineteenth transistor Q19, a thirteenth resistor R13, and a twenty-fifth resistor R25; the base of the nineteenth transistor Q19 serves as the input port of the intermediate frequency amplifier unit 30, the collector of the nineteenth transistor Q19 is grounded, the emitter of the nineteenth transistor Q19 is connected to one end of the thirteenth resistor R13 and one end of the twenty-fifth resistor R25, the other end of the thirteenth resistor R13 is the output port IFOUT of the intermediate frequency amplifier unit 30, and the other end of the twenty-fifth resistor R25 is connected to the power supply VEE.

[0052] In one embodiment, the entire ultra-wideband dual-mode mixer circuit with on-chip balun can be fed with negative voltage, so that the RF port / LO port can be close to 0V potential. The load can be directly connected at the port without the need for an ultra-wideband DC blocking capacitor, which also helps to eliminate the substrate bias effect and back gate effect.

[0053] In one embodiment, the operating frequency, bandwidth, and bias are taken into account, and the semiconductor is manufactured using appropriate semiconductor technology, such as GaAs or InP HBT process, but not limited to these.

[0054] Among them, resistors R1-R10 and R14-R25 are circuit loads and also have the function of adjusting the DC bias voltage of the transistor. Resistor R13 is the intermediate frequency load, and resistors R11 and R12 are mainly used for emitter degradation, which can improve the linearity of the mixer.

[0055] The aforementioned ultra-wideband dual-mode mixer circuit with on-chip balun uses DC coupling technology to design a local oscillator differential balun unit, a mixer unit with RF differential balun, and an intermediate frequency amplifier unit. This avoids the use of DC-intercepting capacitors between various functional circuits, which helps to greatly reduce the chip area and improve the system integration. At the same time, it can also extend the operating frequency of the ultra-wideband mixer to DC.

[0056] In one example, an ultra-wideband dual-mode mixer circuit with an on-chip balun is described. The relevant circuit component parameters are as follows: The transistors Q1 to Q18 in the ultra-wideband dual-mode mixer circuit with on-chip balun are InP HBTs with an emitter width of 0.7 μm.

[0057] The ultrawideband dual-mode mixer circuit with on-chip balun operates at a voltage VEE of -6 V and consumes 75 mA.

[0058] The test results of the ultra-wideband dual-mode mixer circuit with on-chip balun in the embodiment are as follows: Figures 4 to 8 As shown, the local oscillator power is 0 dBm, and the output intermediate frequency is 1 GHz. Test results show that the ultra-wideband dual-mode mixer circuit with on-chip balun provided in this application can simultaneously achieve fundamental frequency mixing and third harmonic mixing, operating within an ultra-wide bandwidth of DC-67 GHz, solving the problem of the difficulty in implementing a vector network high-frequency local oscillator. When operating in fundamental frequency mixing mode, the operating frequency band is DC-26.5 GHz, at which point the mixer's conversion loss is less than 8 dB, and the LO-RF port isolation is greater than 55 dB; when operating in third harmonic mixing mode, the operating frequency band is 26.5 GHz - 67 GHz, at which point the mixer's conversion loss is less than 23 dB.

[0059] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An ultra-wideband dual-mode mixer circuit with on-chip balun, characterized by, The circuit includes: a local oscillator differential balun unit, a mixer unit with radio frequency differential balun, and an intermediate frequency amplifier unit; The LO port of the local oscillator differential balun unit is connected to the signal output from the local oscillator source in the vector network analysis (VNA) system. The RF port of the mixer unit is connected to the signal to be measured after VNA preprocessing. The output port of the local oscillator differential balun unit is connected to the local oscillator input port of the mixer unit. The output port of the mixer unit is connected to the input port of the intermediate frequency amplifier unit. The local oscillator signal in the vector network analyzer is processed by the local oscillator differential balun unit to obtain two local oscillator differential signals. The high-frequency test signal, which has been preprocessed by the vector network analyzer, is input to the RF port of the mixer unit to obtain two radio frequency differential signals. The two radio frequency differential signals are mixed with the two local oscillator differential signals to obtain the required intermediate frequency (IF) signal. The IF signal is finally amplified by the IF amplifier unit and output from the output port of the IF amplifier unit. The local oscillator differential balun unit includes: a first emitter follower, a first-stage differential amplifier circuit, a second emitter follower, a second-stage differential amplifier circuit, and a third emitter follower; The input terminal of the first emitter follower is the LO port of the local oscillator differential balun unit. The output terminal of the first emitter follower is connected to the input terminal of the first stage differential amplifier circuit. The output terminal of the first stage differential amplifier circuit is connected to the input terminal of the second emitter follower. The output terminal of the second emitter follower is connected to the input terminal of the second stage differential amplifier circuit. The output terminal of the second stage differential amplifier circuit is connected to the input terminal of the third emitter follower. The output terminal of the third emitter follower is the output port of the local oscillator differential balun unit. The mixer unit includes an input emitter follower, an RF transconductance amplifier stage, and an LO switching stage; The input terminal of the input emitter follower serves as the RF port of the mixer unit. The output terminal of the input emitter follower is connected to the input terminal of the RF transconductance amplifier stage. The output terminal of the RF transconductance amplifier stage is connected to the input terminal of the LO switch stage. The output terminal of the LO switch stage serves as the output port of the mixer unit. The local oscillator input terminal of the LO switch stage serves as the local oscillator input port of the mixer unit.

2. The circuit according to claim 1, characterized in that, The first emitter follower includes: a first transistor, a second transistor, a first resistor, a second resistor, a fourteenth resistor, and a fifteenth resistor; The base of the first transistor serves as the input terminal of the first emitter follower. The base of the first transistor is connected to one end of the first resistor, and the emitter of the first transistor is connected to one end of the fourteenth resistor. The base of the second transistor is connected to one end of the second resistor, and the emitter of the second transistor is connected to one end of the fifteenth resistor. The collectors of the first and second transistors are grounded, and the other ends of the first and second resistors are grounded. The other ends of the fourteenth and fifteenth resistors are connected to a power supply. The emitters of the first and second transistors serve as the output terminals of the first emitter follower.

3. The circuit according to claim 1, characterized in that, The first-stage differential amplifier circuit includes a third transistor, a fourth transistor, a third resistor, a fourth resistor, and a sixteenth resistor; The bases of the third and fourth transistors serve as the input terminals of the first-stage differential amplifier circuit. The emitters of the third and fourth transistors are connected to one end of the sixteenth resistor. The collector of the third transistor is connected to one end of the third resistor, and the collector of the fourth transistor is connected to one end of the fourth resistor. The other ends of the third and fourth resistors are grounded, and the other end of the sixteenth resistor is connected to the power supply. The collectors of the third and fourth transistors serve as the output terminals of the first-stage differential amplifier circuit.

4. The circuit according to claim 1, characterized in that, The second emitter follower includes: a fifth transistor, a sixth transistor, a seventeenth resistor, and an eighteenth resistor; The bases of the fifth and sixth transistors serve as the input terminals of the second emitter follower. The emitter of the fifth transistor is connected to one end of the seventeenth resistor, and the emitter of the sixth transistor is connected to one end of the eighteenth resistor. The collectors of the fifth and sixth transistors are grounded, and the other ends of the seventeenth and eighteenth resistors are connected to a power supply. The emitters of the fifth and sixth transistors serve as the output terminals of the second emitter follower.

5. The circuit according to claim 1, characterized in that, The second-stage differential amplifier circuit includes: a seventh transistor, an eighth transistor, a fifth resistor, a sixth resistor, and a nineteenth resistor; The bases of the seventh and eighth transistors serve as the input terminals of the second-stage differential amplifier circuit. The emitters of the seventh and eighth transistors are connected to one end of the nineteenth resistor. The collector of the seventh transistor is connected to one end of the fifth resistor, and the collector of the eighth transistor is connected to one end of the sixth resistor. The other ends of the fifth and sixth resistors are grounded, and the other end of the nineteenth resistor is connected to the power supply. The collectors of the seventh and eighth transistors serve as the output terminals of the second-stage differential amplifier circuit.

6. The circuit according to claim 1, characterized in that, The third emitter follower includes a ninth transistor, a tenth transistor, a twentieth resistor, and a twenty-first resistor; The bases of the ninth and tenth transistors serve as the input terminals of the third emitter follower. The emitter of the ninth transistor is connected to one end of the twentieth resistor, and the emitter of the tenth transistor is connected to one end of the twentieth resistor. The collectors of the ninth and tenth transistors are grounded, and the other ends of the twentieth and twentieth resistors are connected to a power supply. The emitters of the ninth and tenth transistors serve as the output terminals of the third emitter follower.

7. The circuit according to claim 1, characterized in that, The input emitter follower includes a seventeenth transistor, an eighteenth transistor, a ninth resistor, a tenth resistor, a twenty-third resistor, and a twenty-fourth resistor; The base of the seventeenth transistor serves as the input terminal of the input emitter follower. The base of the seventeenth transistor is connected to one end of the tenth resistor. The emitter of the seventeenth transistor is connected to one end of the twenty-fourth resistor. The base of the eighteenth transistor is connected to one end of the ninth resistor. The emitter of the eighteenth transistor is connected to one end of the twenty-third resistor. The collectors of the seventeenth and eighteenth transistors are grounded. The other ends of the ninth and tenth resistors are grounded. The other ends of the twenty-third and twenty-fourth resistors are connected to the power supply. The emitters of the seventeenth and eighteenth transistors serve as the output terminals of the input emitter follower.

8. The circuit according to claim 1, characterized in that, The RF transconductance amplifier stage includes a fifteenth transistor, a sixteenth transistor, an eleventh resistor, a twelfth resistor, and a twenty-second resistor; The bases of the fifteenth and sixteenth transistors serve as the input terminals of the RF transconductance amplifier stage. The emitter of the fifteenth transistor is connected to one end of the eleventh resistor, and the emitter of the sixteenth transistor is connected to one end of the twelfth resistor. The other ends of the eleventh and twelfth resistors are connected to one end of the twenty-second resistor, and the other end of the twenty-second resistor is connected to the power supply. The collectors of the fifteenth and sixteenth transistors serve as the output terminals of the RF transconductance amplifier stage.

9. The circuit according to claim 1, characterized in that, The LO switching stage includes an eleventh transistor, a twelfth transistor, a thirteenth transistor, a fourteenth transistor, a seventh resistor, and an eighth resistor; The emitters of the eleventh, twelfth, thirteenth, and fourteenth transistors serve as the input terminals of the LO switching stage. The bases of the eleventh, twelfth, thirteenth, and fourteenth transistors serve as the local oscillator input terminals of the LO switching stage. The collectors of the eleventh and thirteenth transistors are connected to one end of the seventh resistor. The collectors of the twelfth and fourteenth transistors are connected to one end of the eighth resistor. The collectors of the twelfth and fourteenth transistors, after being connected, serve as the output terminals of the LO switching stage. The other ends of the seventh and eighth resistors are grounded.

10. The circuit according to claim 1, characterized in that, The intermediate frequency amplification unit includes a nineteenth transistor, a thirteenth resistor, and a twenty-fifth resistor; The base of the nineteenth transistor serves as the input port of the intermediate frequency amplifier unit. The collector of the nineteenth transistor is grounded. The emitter of the nineteenth transistor is connected to one end of the thirteenth resistor and one end of the twenty-fifth resistor. The other end of the thirteenth resistor is the output port of the intermediate frequency amplifier unit, and the other end of the twenty-fifth resistor is connected to the power supply.

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