Millimeter wave broadband high-power frequency doubler

Abstract

The millimeter wave broadband high-power frequency doubler comprises an input matching network, a frequency doubling unit based on an inductor-capacitor common-mode resonance structure and an output matching network. Wherein the input matching network converts an input fundamental frequency signal into a differential signal through a single-ended to differential transformer balun and inputs the differential signal to a grid electrode of a double-frequency unit transistor, and the double-frequency unit adopts a common-mode resonance structure based on an inductor and a capacitor. Common-mode harmonic loss caused by a transistor parasitic effect in a traditional double-frequency structure is offset through resonance, the conversion gain and the output power of the double-frequency core structure are improved, and meanwhile the input impedance and the output impedance of the double-frequency core part are optimized through a common-mode resonance structure based on an inductor and a capacitor. The impedance matching effect under the high-frequency condition is improved, and the working bandwidth and the output power of the frequency doubler are improved.

Description

Technical Field

[0001] The invention relates to a frequency multiplier in a millimeter wave integrated circuit, and in particular to a millimeter wave broadband high-power doubler based on inductor-capacitor common-mode resonance. Background Art

[0002] Millimeter waves have the advantages of short wavelength, high reliability, strong anti-interference ability and wide bandwidth. Therefore, the circuits and systems used in the millimeter wave frequency band are small in size and easy to miniaturize and integrate. In recent years, millimeter wave circuits have been widely used and developed in the fields of national defense, medical imaging, automotive electronics, etc.

[0003] In the current research on the application of millimeter wave communication technology, high-performance millimeter wave frequency sources are key unit components in communication systems. There are many difficulties and challenges in the design of frequency sources, which need to meet the requirements of the communication system for spectrum purity, output power and bandwidth, phase noise, power consumption and efficiency. There are generally two ways to design millimeter wave frequency sources: First, design a voltage-controlled oscillator in the required frequency band. Since the millimeter wave frequency band is higher than the frequency of traditional communication, the parasitic effects of passive devices in this frequency band will cause certain performance degradation, resulting in the various performances of the voltage-controlled oscillator being difficult to meet the system requirements. At the same time, the isolation problem with the back-end unit will also affect the normal working state of the frequency source; Second, through the design of the frequency multiplication link, the low-frequency frequency source is multiplied to obtain the high-order harmonic frequency of the low-frequency frequency source. Since the design of this solution only requires the voltage-controlled oscillator to work in a lower frequency band, the parasitic effect of the quality factor of the passive component when the frequency is increased is relatively small, but it is also necessary to achieve better harmonic suppression and bandwidth power requirements through design.

[0004] The output power of the harmonic component after frequency multiplication is significantly lower than the input signal amplitude. Since the signal is relatively weak after passing through the frequency multiplier. In practical applications, signal frequency multiplication needs to be achieved through multi-stage frequency multiplication. Therefore, it is particularly necessary to improve its output power by optimizing the frequency multiplier's own structure or designing the subsequent amplification circuit, and to be able to work stably within a sufficiently wide frequency range to meet the input requirements of subsequent units. Summary of the invention

[0005] Technical problem: In order to solve the problems of low output power and structure not fully suitable for millimeter-wave high-frequency conditions in traditional frequency doublers, a frequency doubler based on inductor-capacitor common-mode resonance is proposed. It can reduce the loss of second harmonic caused by transistor parasitic capacitance through inductor-capacitor common-mode resonance, and reduce the difficulty of input-output matching design, so as to achieve broadband and high-power second harmonic output under high-frequency conditions.

[0006] Technical solution: A millimeter-wave broadband high-power doubler of the present invention comprises an input matching network, a doubler unit based on inductor-capacitor common-mode resonance, and an output matching network;

[0007] The input matching network is composed of a transformer structure formed by coupling a primary inductor and a secondary inductor, as well as a capacitor and a capacitor; one end of the primary inductor is connected to the input end of the baseband signal, and the other end is grounded, and the capacitor is connected in parallel with the primary inductor between the signal input end and the ground; one end of the secondary inductor is connected to the gate of the first transistor in the double frequency unit, and the other end is connected to the gate of the second transistor in the double frequency unit, and the capacitor is connected between the gates of the two transistors in the double frequency unit and connected in parallel with the secondary inductor; the double frequency unit bias voltage is connected to the center tap position of the secondary inductor through a resistor, and one end of the capacitor is connected to the center tap position of the secondary inductor, and the other end is grounded;

[0008] The double frequency unit based on inductor-capacitor common mode resonance is composed of a first transistor and a second transistor, and a first inductor, a second inductor, a first capacitor, and a second capacitor participating in the inductor-capacitor common mode resonance; the sources of the first and second transistors are directly grounded; the gates of the first and second transistors are respectively connected to the two ends of the secondary inductor coil in the input matching network as the input of the baseband signal; the drains of the first and second transistors are directly connected to one end of the output matching network; the first inductor and the first capacitor participating in the inductor-capacitor common mode feedback are connected in series, and one end is connected to the gate of the first transistor and the other end is connected to the drain of the first transistor after the series connection; the second inductor and the second capacitor are connected in series, and one end is connected to the gate of the second transistor and the other end is connected to the drain of the second transistor after the series connection;

[0009] The output matching network is composed of a transformer structure formed by coupling a primary inductor and a secondary inductor; one end of the primary inductor is connected to the drain output of the double frequency unit based on the common mode resonance of the inductor and capacitor, and the other end is connected to the power supply for the first transistor and the second transistor; one end of the secondary inductor is connected to the input end of the second harmonic signal, and the other end is grounded; the capacitor is connected in parallel with the secondary inductor between the signal output end and the ground;

[0010] One end of the capacitor in the input matching network is connected to the center tap position of the secondary inductor coil, and the other end is grounded; in the common mode state, the capacitor and the secondary inductor coil form a resonant cavity, and work together with the inductor and capacitor part of the double frequency unit based on the inductor-capacitor common mode resonance to reduce the common mode loss of the output second harmonic;

[0011] The first inductor and the first capacitor of the double frequency unit based on inductor-capacitor common mode resonance participating in the inductor-capacitor common mode feedback are connected in series and connected between the gate and the drain of the first transistor. The parasitic capacitance between the first capacitor and the gate and drain of the first transistor resonates with the first inductor at the second harmonic, thereby reducing the output second harmonic loss caused by the parasitic capacitance of the first transistor in the double frequency unit; the second inductor and the second capacitor are connected in series and connected between the gate and the drain of the second transistor. The parasitic capacitance between the second capacitor and the gate and drain of the second transistor resonates with the second inductor at the second harmonic, thereby reducing the output second harmonic loss caused by the parasitic capacitance of the second transistor in the double frequency unit. The first inductor and the second inductor are selected to have an inductance value that maximizes the output second harmonic amplitude of the double frequency unit under a certain input signal amplitude.

[0012] Beneficial effects:

[0013] 1. The present invention adopts a broadband high-power doubler based on inductor-capacitor common-mode resonance, which is composed of an input matching network, a doubler unit based on inductor-capacitor common-mode resonance, and an output matching network.

[0014] 2. The present invention adopts a common-mode resonant structure based on inductance and capacitance, which offsets the common-mode harmonic loss caused by the parasitic effect of transistors in the traditional doubler structure through resonance, thereby improving the conversion gain and output power of the doubler.

[0015] 3. The present invention adopts a common-mode resonant structure based on inductance and capacitance, optimizes the input impedance and output impedance of the double frequency core part, improves the impedance matching effect under high frequency conditions, and realizes broadband and high-power second harmonic output under high frequency conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a circuit structure diagram of the frequency doubler in the present invention;

[0017] Figure 2 It is a schematic diagram of the structure of the double frequency unit based on the common mode resonance of the inductor and capacitor in the present invention;

[0018] Figure 3 is the output power bandwidth of the frequency doubler in the present invention;

[0019] Figure 4 is the conversion gain of the frequency doubler in the present invention;

[0020] Figure 5 It is the harmonic suppression of the frequency doubler in the present invention;

[0021] The figure includes: input matching network part, primary inductor LS1, primary coil parallel inductor CS1, secondary inductor LP1, secondary coil parallel inductor CP1, first resonant capacitor C1; signal input port IN; bias voltage Vb1, resistor R1; double frequency part based on inductor and capacitor common mode resonance, transistor M1, transistor M2, first resonant inductor L1, second resonant inductor L2, second resonant capacitor C2, third resonant capacitor C3; output matching network part, primary inductor LS2, secondary inductor LP2, secondary coil parallel inductor CP2. DETAILED DESCRIPTION

[0022] The present invention is further explained below in conjunction with the accompanying drawings and examples. The implementation methods of the present invention include but are not limited to the following examples.

[0023] This embodiment provides a broadband high power frequency doubler, such as Figure 1 As shown, it consists of an input matching network I, a double frequency unit II based on inductor and capacitor common mode resonance, and an output matching network III.

[0024] The input matching network I is composed of a transformer structure formed by coupling a primary inductor LS1 and a secondary inductor LP1, as well as capacitors CS1 and CP1; one end of the primary inductor LS1 is connected to the input end IN of the baseband signal, and the other end is grounded, and the capacitor CS1 is connected in parallel with the primary inductor LS1 between the signal input end IN and the ground; one end of the secondary inductor LP1 is connected to the gate of the transistor M1 in the double frequency unit, and the other end is connected to the gate of the transistor M2 in the double frequency unit, and the capacitor CP1 is connected between the gates of the two transistors in the double frequency unit and connected in parallel with the secondary inductor LP1; the double frequency unit bias voltage Vb1 is connected to the center tap position of the secondary inductor LP1 through the resistor R1, and one end of the capacitor C1 is connected to the center tap position of the secondary inductor LP1, and the other end is grounded;

[0025] The double frequency unit II based on inductor-capacitor common mode resonance is composed of a transistor M1, a transistor M2, and an inductor L1, an inductor L2, a capacitor C3, and a capacitor C4 participating in the inductor-capacitor common mode resonance; the sources of the transistors M1 and M2 are directly grounded; the gates of the transistors M1 and M2 are respectively connected to the two ends of the secondary inductor coil in the input matching network as the input of the baseband signal; the drains of the transistors M1 and M2 are directly connected to one end of the output matching network III; the inductor L1 and the capacitor C2 participating in the inductor-capacitor common mode feedback are connected in series, and one end is connected to the gate of the transistor M1 and the other end is connected to the drain of the transistor M1 after the series connection; the inductor L2 and the capacitor C3 are connected in series, and one end is connected to the gate of the transistor M2 and the other end is connected to the drain of the transistor M2 after the series connection; the coupling coefficient between the inductor L1 and the inductor L2 is K3;

[0026] The output matching network III is composed of a transformer structure formed by coupling a primary inductor LS2 and a secondary inductor LP2; one end of the primary inductor LS2 is connected to the drain output of the double frequency unit II based on the common mode resonance of the inductor and capacitor, and the other end is connected to the power supply VDD1 for powering the transistor M1 and the transistor M2; one end of the secondary inductor LP2 is connected to the input end OUT of the second harmonic signal, and the other end is grounded; the capacitor CP2 is connected in parallel with the secondary inductor LP2 between the signal output end OUT and the ground;

[0027] In order to meet the needs of millimeter wave communication, the signal source realized by the frequency doubling structure needs to be able to meet the harmonic output requirements of broadband and high power under high frequency conditions. In the corresponding frequency band, the influence of the parasitic capacitance of the transistor is more obvious, resulting in greater common mode loss caused by the parasitic capacitance between the gate and drain in the traditional double frequency structure. At the same time, the parasitic effect of the inductor in the input and output matching network is also more obvious, resulting in the overall output power of the double frequency structure being difficult to meet the system requirements. In the present invention, a working resonant capacitor is added to the input matching network, so that it resonates with the secondary inductor in the input matching network at the output second harmonic signal frequency, and presents a low resistance state in the common mode path; at the same time, an inductor and a capacitor are added to the traditional double frequency structure, and the parasitic capacitance between the gate and drain of the transistor is parallel resonated at the output second harmonic signal frequency, and presents a high resistance state in the common mode path. Under the joint action of the two resonant cavities, the second harmonic current component generated by the transistor is less reversely amplified through the transistor gate, reducing the loss of the output second harmonic signal, and improving the output power and output bandwidth of the overall double frequency structure.

[0028] Based on the above working principle, this embodiment designs and simulates the above circuit based on 40nm CMOS technology, verifying the practicality of the present invention.

[0029] Figure 2 A method for realizing a double frequency unit based on inductor-capacitor common mode resonance is given. Figure 3 The output power 3dB bandwidth of the doubler is given. When the input frequency is 59.15~82.36GHz, the output is 4.15 to 7.15dBm and the 3dB bandwidth is 32.8%. Figure 4 The conversion gain of the doubler is given. When the input frequency is 59.15~82.36GHz and the input power is 12dBm, the conversion gain is -7.85 to -4.85dB; when the input frequency is 60~81.44GHz and the input power is 10dBm, the conversion gain is -6.44 to -3.44dB; when the input frequency is 62.96~79.56GHz and the input power is 5dBm, the conversion gain is -4.54 to -1.54dB. Figure 5The harmonic suppression of the doubler is given, and the fundamental, third harmonic and fourth harmonic all achieve harmonic suppression of more than 19.4dBc within the output 3dB bandwidth.

[0030] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A millimeter wave broadband high power doubler, characterized in that: It includes an input matching network (I), a double frequency unit based on inductor-capacitor common mode resonance (II), and an output matching network (III); The input matching network (I) is composed of a transformer structure formed by coupling a primary inductor LS1 and a secondary inductor LP1, as well as a capacitor CS1 and a capacitor CP1; one end of the primary inductor LS1 is connected to an input terminal IN of a baseband signal, and the other end is grounded; the capacitor CS1 is connected in parallel with the primary inductor LS1 between the signal input terminal IN and the ground; One end of the secondary inductor LP1 is connected to the gate of the transistor M1 in the double frequency unit, and the other end is connected to the gate of the transistor M2 in the double frequency unit. The capacitor CP1 is connected between the gates of the two transistors in the double frequency unit and is connected in parallel with the secondary inductor LP1. The double frequency unit bias voltage Vb1 is connected to the center tap position of the secondary inductor LP1 through the resistor R1. One end of the capacitor C1 is connected to the center tap position of the secondary inductor LP1, and the other end is grounded. The double frequency unit (II) based on the common mode resonance of inductance and capacitance is composed of a transistor M1, a transistor M2, and an inductor L1, an inductor L2, a capacitor C3, and a capacitor C4 participating in the common mode resonance of inductance and capacitance; the sources of the transistors M1 and M2 are directly grounded; The gates of transistors M1 and M2 are respectively connected to the two ends of the secondary inductor coil in the input matching network as the input of the baseband signal; the drains of transistors M1 and M2 are directly connected to one end of the output matching network (III); the inductor L1 and the capacitor C2 participating in the inductor-capacitor common-mode feedback are connected in series, and one end of the series connection is connected to the gate of transistor M1 and the other end is connected to the drain of transistor M1; the inductor L2 and the capacitor C3 are connected in series, and one end of the series connection is connected to the gate of transistor M2 and the other end is connected to the drain of transistor M2; the coupling coefficient between the inductor L1 and the inductor L2 is K3; The output matching network (III) is composed of a transformer structure formed by coupling a primary inductor LS2 and a secondary inductor LP2; one end of the primary inductor LS2 is connected to the drain output of the double frequency unit based on the inductor-capacitor common mode resonance, and the other end is connected to the power supply VDD1 for powering the transistor M1 and the transistor M2; one end of the secondary inductor LP2 is connected to the input end OUT of the second harmonic signal, and the other end is grounded; the capacitor CP2 is connected in parallel with the secondary inductor LP2 between the signal output end OUT and the ground.

2. The millimeter wave broadband high power doubler according to claim 1, characterized in that: One end of the capacitor C1 in the input matching network (I) is connected to the center tap position of the secondary inductor LP1, and the other end is grounded; in the common mode state, the capacitor C1 and the secondary inductor LP1 form a resonant cavity, which works together with the inductor and capacitor parts in the doubler unit (II) based on inductor-capacitor common mode resonance to reduce the common mode loss of the output second harmonic.

3. The millimeter wave broadband high power doubler according to claim 1, characterized in that: The double frequency unit (II) based on inductor-capacitor common mode resonance comprises an inductor L1 and a capacitor C2 which are connected in series and participate in inductor-capacitor common mode feedback and are connected between the gate and drain of the transistor M1. The parasitic capacitance between the capacitor C2 and the gate and drain of the transistor M1 resonates with the inductor L1 at the second harmonic, thereby reducing the output second harmonic loss caused by the parasitic capacitance of the transistor M1 in the double frequency unit; the inductor L2 and the capacitor C3 are connected in series and are connected between the gate and drain of the transistor M2. The parasitic capacitance between the capacitor C3 and the gate and drain of the transistor M2 resonates with the inductor L2 at the second harmonic, thereby reducing the output second harmonic loss caused by the parasitic capacitance of the transistor M2 in the double frequency unit. The inductor L1 and the inductor L2 are selected to have inductance values ​​that maximize the output second harmonic amplitude of the double frequency unit under a certain input signal amplitude.

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