Differential hartley oscillator

Abstract

This invention discloses a differential Hartley oscillator, comprising an equal-amplitude differential drive module for generating equal-amplitude differential current signals to provide differential resonant current for an equal-amplitude differential resonant cavity; and an equal-amplitude differential resonant cavity for converting the equal-amplitude differential current signals into differential voltage signals and for inputting the equal-amplitude differential voltage signals into the equal-amplitude differential drive module; wherein a first current signal terminal is connected to a second voltage signal terminal, and the second current signal terminal is connected to the first voltage signal terminal; the equal-amplitude differential resonant cavity has two differential-mode impedance peaks, and based on the synergistic effect of its own inductive coupling effect and frequency phase tuning, the equal-amplitude differential resonant cavity operates at the differential-mode impedance peak at a high operating frequency. This invention can achieve differential output with consistent amplitude and effectively suppress phase noise.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency integrated circuit technology, and particularly relates to a differential Hartley oscillator operating in a high-frequency mode. Background Technology

[0002] In 6G communication systems, the phase noise performance of a frequency source is primarily determined by its core module, the voltage-controlled oscillator (VCO). Low-phase-noise VCOs are fundamental to achieving low-phase-noise frequency sources. However, as transistor frequencies rise to millimeter-wave and terahertz bands, oscillators face numerous challenges, such as reduced device energy efficiency, deterioration of the quality factor of small inductors, and increasingly significant parasitic effects. Therefore, achieving low-phase-noise VCOs at high operating frequencies has become a problem that needs to be solved. In recent years, a Colpitts oscillator based on phase feedback operating at high frequencies has been reported. However, this design relies on inductive coupling to achieve differential output, which suffers from the problem of pseudo-differential output signals due to mismatch.

[0003] In 2010, a fully differential Hartley oscillator chip was reported, which implemented a fully differential Hartley oscillator structure and avoided the biasing difficulties of traditional Hartley oscillators. However, this oscillator was still limited to complementary NMOS and PMOS structures, which restricted its maximum operating frequency. Existing Hartley oscillators typically rely on a tail current source to achieve stable oscillation. The two-stage stacked transistors require higher supply voltages and consume more power. In addition, the additional current source also limits the voltage swing during oscillation, introduces noise, and ultimately degrades phase noise performance. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a differential Hartley oscillator operating in a high-frequency mode, which can achieve differential output with consistent amplitude and effectively suppress phase noise.

[0005] Technical solution: The differential Hartley oscillator of the present invention includes an equal-amplitude differential drive module and an equal-amplitude differential resonant cavity. The equal amplitude differential driving module is used to generate a differential current signal of equal amplitude; the equal amplitude differential driving module is connected to the equal amplitude differential resonant cavity through a first current signal terminal and a second current signal terminal, and provides a differential current signal of equal amplitude to the equal amplitude differential resonant cavity. The equal-amplitude differential resonant cavity is connected to the equal-amplitude differential drive module through a first voltage signal terminal and a second voltage signal terminal, wherein the first current signal terminal is connected to the second voltage signal terminal, and the second current signal terminal is connected to the first voltage signal terminal; The equal-amplitude differential resonant cavity includes multiple inductors and multiple capacitors. Based on the coupling effect of paired inductors and the synergistic effect of frequency and phase tuning of capacitors, the equal-amplitude differential resonant cavity has two differential-mode impedance peaks. The equal-amplitude differential resonant cavity operates at the differential-mode impedance peak at a high operating frequency. Thus, the equal-amplitude differential resonant cavity in operating mode is used to convert the equal-amplitude differential current signal into an equal-amplitude differential voltage signal, and to input the equal-amplitude differential voltage signal into the equal-amplitude differential drive module.

[0006] Optionally, the equal-amplitude differential resonant cavity includes a coupling induction module and a frequency and phase tuning module. The coupling sensing module includes multiple inductors, which are used to make the output signal of the equal amplitude differential resonant cavity a differential voltage signal of equal amplitude through the coupling effect between their own inductors. The frequency phase tuning module includes multiple capacitors, which are used to tune the frequency of the equal-amplitude differential voltage signal output by the coupling sensing module by adjusting the capacitance value, and to tune the phase of the signal fed back to the coupling sensing module by adjusting the capacitance value.

[0007] Optionally, the frequency phase tuning module includes a first capacitor C. D1 First frequency tuning branch, second capacitor C D2 The second frequency tuning branch, the first capacitor C D1 One end is connected to the first current signal terminal, and the first capacitor C D1 The other end is connected to one end of the first frequency tuning branch, and the other end of the first frequency tuning branch is connected to the first voltage signal terminal. The second capacitor C D2 One end of the capacitor is connected to the second current signal terminal, and the second capacitor C D2 The other end is connected to one end of the second frequency tuning branch, and the other end of the second frequency tuning branch is connected to the second voltage signal terminal; The first frequency tuning branch includes a first switched capacitor array for coarse tuning of the operating frequency and a first variable capacitor array for fine tuning of the operating frequency, which are connected in parallel. The second frequency tuning branch includes a second switched capacitor array for coarse tuning of the operating frequency and a second variable capacitor array for fine tuning of the operating frequency, which are connected in parallel.

[0008] Optionally, the frequency phase tuning module further includes a third variable capacitor array for fine tuning of the operating frequency, one end of the third variable capacitor array being connected to the first voltage signal terminal and the other end of the third variable capacitor array being connected to the second voltage signal terminal.

[0009] Optionally, the frequency phase tuning module includes a first capacitor C. D1A first switched capacitor array used to achieve coarse tuning of the operating frequency, and a second capacitor C. D2 A second switched capacitor array for coarse tuning of the operating frequency and a third variable capacitor array for fine tuning of the operating frequency, wherein the first capacitor C D1 One end is connected to the first current signal terminal, and the first capacitor C D1 The other end is connected to one end of the first switched capacitor array, and the other end of the first switched capacitor array is connected to the first voltage signal terminal. The second capacitor C D2 One end of the capacitor is connected to the second current signal terminal, and the second capacitor C D2 One end of the third variable capacitor array is connected to one end of the second switched capacitor array, and the other end of the second switched capacitor array is connected to the second voltage signal terminal; one end of the third variable capacitor array is connected to the first voltage signal terminal, and the other end of the third variable capacitor array is connected to the second voltage signal terminal.

[0010] Optionally, the frequency phase tuning module further includes a third capacitor C connected in series. D3 and the fourth capacitor C D4 The third capacitor C D3 The other end is connected to the first voltage signal terminal, and the fourth capacitor C D4 The other end is connected to the second voltage signal terminal.

[0011] Optionally, the first switched capacitor array includes multiple parallel-connected first switched capacitor series modules, wherein each first switched capacitor series module includes a fifth capacitor C connected in series sequentially. SCA1 First switch SW1 and sixth capacitor C SCA2 The fifth capacitor C SCA1 The other end is connected to the first capacitor C D1 Connection, sixth capacitor C SCA2 The other end is connected to the first voltage signal terminal; the second switched capacitor array includes multiple parallel second switched capacitor series modules, wherein each second switched capacitor series module includes a seventh capacitor C connected in series sequentially. SCA3 The second switch SW2 and the eighth capacitor C SCA4 The seventh capacitor C SCA3 The other end is connected to the second capacitor C D2 Connection, eighth capacitor C SCA4 The other end is connected to the second voltage signal terminal; The first variable capacitor array includes a first variable capacitor C connected in series. var1 Second variable capacitor C var2 The first variable capacitor C var1 Second variable capacitor C var2 The connection point with the first control voltage V CTRL1 Connection, first variable capacitor Cvar1 The other end is connected to the first capacitor C D1 Connection, second variable capacitor C var2 The other end is connected to the first voltage signal terminal; The second variable capacitor array includes a third variable capacitor C connected in series. var3 and the fourth variable capacitor C var4 The third variable capacitor C var3 and the fourth variable capacitor C var4 The connection point with the second control voltage V CTRL2 Connection, third variable capacitor C var3 The other end is connected to the second capacitor C D2 Connection, fourth variable capacitor C var4 The other end is connected to the second voltage signal terminal.

[0012] Optionally, the third variable capacitor array includes a fifth variable capacitor C connected in series. var5 and the sixth variable capacitor C var6 The fifth variable capacitor C var5 and the sixth variable capacitor C var6 The connection point and the third control voltage V CTRL3 Connection, fifth variable capacitor C var5 The other end is connected to the first voltage signal terminal, and the sixth variable capacitor C var6 The other end is connected to the second voltage signal terminal.

[0013] Optionally, the coupling sensing module includes a first inductor L1, a second inductor L2, a third inductor L3, and a fourth inductor L4, wherein the first inductor L1 and the fourth inductor L4 are mutually inductively coupled, and the second inductor L2 and the third inductor L3 are mutually inductively coupled. The terminals of the first inductor L1 and the second inductor L2 are connected to the power supply; the terminal of the first inductor L1 with the opposite name is connected to the first current signal terminal; and the terminal of the second inductor L2 with the opposite name is connected to the second current signal terminal. The terminal of the third inductor L3 with the same name is connected to the first capacitor C. D1 The connection point between the first frequency tuning branch and the second current signal branch is connected; the opposite-named terminal of the third inductor L3 is connected to the second current signal terminal; the same-named terminal of the fourth inductor L4 is connected to the first capacitor C. D2 The connection point between the second frequency tuning branch and the fourth inductor L4 is connected to the first current signal terminal.

[0014] Optionally, the equal amplitude differential driving module includes a first transistor M1 and a second transistor M2; The sources of both the first transistor M1 and the second transistor M2 are grounded; The drain of the first transistor M1 serves as the first current signal terminal, and the drain of the second transistor M2 serves as the second current signal terminal. The current signal output from the first current signal terminal and the current signal output from the second current signal terminal constitute the equal-amplitude differential current signal. The gate of the first transistor M1 serves as the first voltage signal terminal, and the gate of the second transistor M2 serves as the second voltage signal terminal, for inputting the equal amplitude differential voltage signal provided by the equal amplitude differential resonant cavity. The drain of the first transistor M1 is connected to the gate of the second transistor M2, and the drain of the second transistor M2 is connected to the gate of the first transistor M1.

[0015] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The present invention directly connects the first current signal terminal to the second voltage signal terminal, and directly connects the second current signal terminal to the first voltage signal terminal, forcing the two output signals of the equal amplitude differential drive module to have the same swing amplitude, avoiding the problem of output swing imbalance caused by inductor mismatch that may be encountered in the traditional method of implementing differential signals only through cross-coupled inductors; The equal amplitude differential resonator of the present invention has two differential mode impedance peaks. Based on the synergistic effect of its own inductor coupling effect and frequency phase tuning, the equal amplitude differential resonator operates at the differential mode impedance peak at a high operating frequency, which improves the operating frequency of the oscillator and effectively suppresses phase noise. Attached Figure Description

[0016] Figure 1 This is a circuit diagram of a conventional differential Hartley oscillator in the prior art; Figure 2 This is a circuit diagram of the first differential Hartley oscillator proposed in this invention; Figure 3 This is a circuit diagram of the second differential Hartley oscillator proposed in this invention; Figure 4 This is a schematic diagram showing the impedance amplitude and phase of the Hartley oscillator proposed in this invention; Figure 5 This is a circuit diagram of the third differential Hartley oscillator proposed in this invention; Figure 6 This is a circuit diagram of the fourth differential Hartley oscillator proposed in this invention;

[0017] Figure 7 This is a circuit diagram of the fifth differential Hartley oscillator proposed in this invention. Detailed Implementation

[0018] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0019] like Figure 1As shown, in a traditional differential Hartley oscillator, the power supply to ground requires two stages of transistors. Therefore, the traditional design requires a higher power supply voltage, and the four transistors introduce more noise and parasitic capacitance, which degrades the overall performance of the oscillator.

[0020] like Figure 2 As shown, this invention proposes a differential Hartley oscillator, including an equal-amplitude differential drive module and an equal-amplitude differential resonant cavity. The equal amplitude differential drive module is used to generate a differential current signal of equal amplitude. The equal amplitude differential drive module is connected to the equal amplitude differential resonant cavity through the first current signal terminal A and the second current signal terminal B, and provides the equal amplitude differential current signal to the equal amplitude differential resonant cavity. The equal-amplitude differential resonant cavity is connected to the equal-amplitude differential drive module through the first voltage signal terminal C and the second voltage signal terminal D, wherein the first current signal terminal A is connected to the second voltage signal terminal D, and the second current signal terminal B is connected to the first voltage signal terminal C; The equal-amplitude differential resonator includes multiple inductors and multiple capacitors. Based on the coupling effect of paired inductors and the synergistic effect of frequency and phase tuning of capacitors, the equal-amplitude differential resonator has two differential-mode impedance peaks. The equal-amplitude differential resonator operates at the differential-mode impedance peak at a high operating frequency. Thus, the equal-amplitude differential resonator in operating mode is used to convert equal-amplitude differential current signals into equal-amplitude differential voltage signals, and to input equal-amplitude differential voltage signals into equal-amplitude differential drive modules.

[0021] In one embodiment, the equal-amplitude differential resonant cavity includes a coupling induction module and a frequency and phase tuning module. The coupling sensing module includes multiple inductors, which are used to make the output signal of the equal amplitude differential resonant cavity a differential voltage signal of equal amplitude through the coupling effect between their own inductors; The frequency phase tuning module includes multiple capacitors, which are used to tune the frequency of the equal-amplitude differential voltage signal output by the coupling induction module by adjusting the capacitance value, and to tune the phase of the signal fed back to the coupling induction module by adjusting the capacitance value.

[0022] In one embodiment, the frequency phase tuning module includes a first capacitor C. D1 First frequency tuning branch, second capacitor C D2 The second frequency tuning branch, the first capacitor C D1 One end is connected to the first current signal terminal A, and the first capacitor C D1 The other end is connected to one end of the first frequency tuning branch, and the other end of the first frequency tuning branch is connected to the first voltage signal terminal C. The second capacitor C D2 One end is connected to the second current signal terminal B, and the second capacitor C D2The other end is connected to one end of the second frequency tuning branch, and the other end of the second frequency tuning branch is connected to the second voltage signal terminal D. The first frequency tuning branch includes a first switched capacitor array for coarse tuning of the operating frequency and a first variable capacitor array for fine tuning of the operating frequency, connected in parallel. The second frequency tuning branch includes a second switched capacitor array for coarse tuning of the operating frequency and a second variable capacitor array for fine tuning of the operating frequency, connected in parallel.

[0023] In one embodiment, the frequency phase tuning module further includes a third variable capacitor array for fine tuning of the operating frequency, one end of the third variable capacitor array being connected to a first voltage signal terminal C, and the other end of the third variable capacitor array being connected to a second voltage signal terminal D.

[0024] In one embodiment, the frequency phase tuning module includes a first capacitor C. D1 A first switched capacitor array used to achieve coarse tuning of the operating frequency, and a second capacitor C. D2 A second switched capacitor array for coarse tuning of the operating frequency and a third variable capacitor array for fine tuning of the operating frequency, wherein the first capacitor C D1 One end is connected to the first current signal terminal A, and the first capacitor C D1 The other end is connected to one end of the first switched capacitor array, and the other end of the first switched capacitor array is connected to the first voltage signal terminal C. The second capacitor C D2 One end is connected to the second current signal terminal B, and the second capacitor C D2 One end of the third variable capacitor array is connected to one end of the second switched capacitor array, and the other end of the second switched capacitor array is connected to the second voltage signal terminal D; one end of the third variable capacitor array is connected to the first voltage signal terminal C, and the other end of the third variable capacitor array is connected to the second voltage signal terminal D.

[0025] like Figure 5 and Figure 6 As shown, in one embodiment, the frequency phase tuning module further includes a third capacitor C connected in series. D3 and the fourth capacitor C D4 The third capacitor C D3 The other end is connected to the first voltage signal terminal C, and the fourth capacitor C D4 The other end is connected to the second voltage signal terminal D. Specifically, this invention selects an appropriate capacitance ratio, based on the third capacitor C. D3 and the fourth capacitor C D4 The capacitance ratio of the capacitors can be used to further adjust the amplitude and phase of the voltage fed back to the gate from the resonant cavity, thereby achieving lower phase noise and making the oscillator more likely to achieve stable oscillation.

[0026] In one embodiment, the first switched capacitor array includes a plurality of first switched capacitor series modules connected in parallel, wherein each first switched capacitor series module includes a fifth capacitor C connected in series sequentially. SCA1 First switch SW1 and sixth capacitor C SCA2 The fifth capacitor C SCA1 The other end is connected to the first capacitor C D1 Connection, sixth capacitor C SCA2 The other end is connected to the first voltage signal terminal C.

[0027] The second switched capacitor array includes multiple parallel-connected second switched capacitor series modules, wherein each second switched capacitor series module includes a seventh capacitor C connected in series sequentially. SCA3 The second switch SW2 and the eighth capacitor C SCA4 The seventh capacitor C SCA3 The other end is connected to the second capacitor C D2 Connection, eighth capacitor C SCA4 The other end is connected to the second voltage signal terminal D.

[0028] like Figure 2 and Figure 3 As shown, in one exemplary embodiment, the first switched capacitor array includes three first switched capacitor series modules connected in parallel. Figure 2 and Figure 3 The three dashed boxes in the middle represent three first switched capacitor series modules connected in parallel. This indicates that the switched capacitor array is a 3-bit bank, that is, a 3-bit first switched capacitor array.

[0029] like Figure 2 and Figure 3 As shown, in one exemplary embodiment, the second switched capacitor array includes three parallel-connected second switched capacitor series modules. Figure 2 and Figure 3 The three dashed boxes in the middle represent three parallel-connected second switched capacitor series modules. This indicates that the switched capacitor array is a 3-bit bank, that is, a 3-bit second switched capacitor array.

[0030] The first variable capacitor array includes first variable capacitors C connected in series. var1 Second variable capacitor C var2 The first variable capacitor C var1 Second variable capacitor C var2 The connection point with the first control voltage V CTRL1 Connection, first variable capacitor C var1 The other end is connected to the first capacitor C D1 Connection, second variable capacitor C var2The other end is connected to the first voltage signal terminal; The second variable capacitor array includes a third variable capacitor C connected in series. var3 and the fourth variable capacitor C var4 The third variable capacitor C var3 and the fourth variable capacitor C var4 The connection point with the second control voltage V CTRL2 Connection, third variable capacitor C var3 The other end is connected to the second capacitor C D2 Connection, fourth variable capacitor C var4 The other end is connected to the second voltage signal terminal D.

[0031] like Figure 5 , Figure 6 and Figure 7 As shown, in one embodiment, the third variable capacitor array includes a fifth variable capacitor C connected in series. var5 and the sixth variable capacitor C var6 The fifth variable capacitor C var5 and the sixth variable capacitor C var6 The connection point and the third control voltage V CTRL3 Connection, fifth variable capacitor C var5 The other end is connected to the first voltage signal terminal C, and the sixth variable capacitor C var6 The other end is connected to the second voltage signal terminal D.

[0032] for Figure 6 and Figure 7 In the middle, the fifth variable capacitor C var5 The capacitance value is equivalent to Figure 3 and Figure 5 The first variable capacitor C var1 and the third variable capacitor C var3 The sum of capacitance values, the sixth variable capacitor C var6 The capacitance value is equivalent to Figure 3 and Figure 5 The second variable capacitor C var2 and the fourth variable capacitor C var4 When the capacitance values ​​are equal, the frequency tuning effects produced by the two circuits are comparable.

[0033] In one embodiment, the coupling sensing module includes a first inductor L1, a second inductor L2, a third inductor L3, and a fourth inductor L4. The first inductor L1 and the fourth inductor L4 are mutually inductively coupled, and the second inductor L2 and the third inductor L3 are mutually inductively coupled. The same-named terminals of the first inductor L1 and the second inductor L2 are connected to the power supply; the opposite-named terminal of the first inductor L1 is connected to the first current signal terminal A; and the opposite-named terminal of the second inductor L2 is connected to the second current signal terminal B. The same-named terminal of the third inductor L3 is connected to the first capacitor C.D1 The connection point between the first frequency tuning branch and the third inductor L3 is connected; the opposite-named terminal of the third inductor L3 is connected to the second current signal terminal B; the same-named terminal of the fourth inductor L4 is connected to the first capacitor C. D2 The connection point between the second frequency tuning branch and the fourth inductor L4 is connected to the first current signal terminal A.

[0034] Specifically, the coupling coefficient between the first inductor L1 and the fourth inductor L4 is k1, and the coupling coefficient between the second inductor L2 and the third inductor L3 is k2. Coupling coefficients k1 and k2 can have the same value or different values; using the same value results in better noise suppression. In this invention, the first inductor L1 and the fourth inductor L4 are mutually coupled, and the second inductor L2 and the third inductor L3 are also mutually coupled. Utilizing the coupling effect between the inductors' own inductances, the quality factor of the equal-amplitude differential resonator when outputting a differential voltage signal is significantly higher than that when outputting a non-inverting voltage signal, thus achieving an actual output of a differential voltage signal with equal amplitude from the equal-amplitude differential resonator.

[0035] In one embodiment, the equal amplitude differential driving module includes a first transistor M1 and a second transistor M2; The sources of both the first transistor M1 and the second transistor M2 are grounded; The drain of the first transistor M1 serves as the first current signal terminal A, and the drain of the second transistor M2 serves as the second current signal terminal B. The current signal output from the first current signal terminal A and the current signal output from the second current signal terminal B constitute the equal amplitude differential current signal. The gate of the first transistor M1 serves as the first voltage signal terminal C, and the gate of the second transistor M2 serves as the second voltage signal terminal D, for inputting the equal amplitude differential voltage signal provided by the equal amplitude differential resonant cavity. The drain of the first transistor M1 is connected to the gate of the second transistor M2, and the drain of the second transistor M2 is connected to the gate of the first transistor M1. In this invention, both the first transistor M1 and the second transistor M2 are NMOS transistors.

[0036] This invention, by employing coupled inductors, requires only one pair of transistors compared to the traditional Hartley oscillator design, which requires a pair of transistors plus a tail current source. This reduces power consumption and avoids noise introduction from the current source, resulting in lower phase noise. Specifically, compared to the traditional differential Hartley structure in the prior art, this invention uses a first inductor L1 and a second inductor L2 to replace the PMOS transistor, thus using only one pair of NMOS transistors and reducing the required maximum supply voltage. This reduces power consumption and increases the voltage swing of the oscillation while maintaining the same operating current. The components include a first switch SW1, a second switch SW2, and a third capacitor C. SCA1 Fourth capacitor C SCA2Fifth capacitor C SCA3 The sixth capacitor C SCA4 The first variable capacitor C var1 The second variable capacitor C var2 The third variable capacitor C var3 The fourth variable capacitor C var4 Fifth variable capacitor C var5 and the sixth variable capacitor C var6 Together, they form the frequency tuning section located at the transistor gate. This includes the first switch SW1, the second switch SW2, and the third capacitor C. SCA1 Fourth capacitor C SCA2 Fifth capacitor C SCA3 and the sixth capacitor C SCA4 A switched capacitor array was formed to achieve coarse tuning of the oscillator's operating frequency. This was achieved by adjusting V... CTRL1 and V CTRL2 The voltage can be used to change the capacitance value of the variable capacitor, thereby achieving continuous fine tuning of the operating frequency. In this invention, as... Figure 2 , Figure 3 , Figure 5 , Figure 6 and Figure 7 Both are left-right symmetrical circuits, and the gates and drains of the first transistor M1 and the second transistor M2 are connected to each other to ensure equal amplitude differential output.

[0037] This design uses inductors L1, L2, L3, and L4 to create two differential-mode impedance peaks. The impedance amplitude and phase from the transistor gate to the drain are as follows: Figure 4 As shown. This invention uses an inductor instead of a current source in a Hartley oscillator, reducing the required supply voltage and power consumption, and improving the oscillation swing while suppressing phase noise. In a conventional cross-coupled oscillator, two transistors jointly participate in the loop's phase feedback, providing a total of 360° phase change. For conventional cross-coupled oscillators, impedance peaks only occur at low operating frequencies. The total phase change of the loop is 0° as required by the Barkhausen criterion for oscillation. Therefore, traditional oscillators operate at low frequency impedance peaks. In the differential Hartley structure proposed in this invention, two transistors participate in the phase feedback of the loop independently, providing only a 180° phase change in a closed loop. Therefore, when the requirement of 0° total phase change in the loop for the Barkhausen criterion during oscillation is met, the design proposed in this invention operates at the impedance peak at a high operating frequency. Furthermore, by using the same values ​​of inductance and capacitance, the design of this invention can increase the operating frequency of the oscillator. On the other hand, while using cross-coupled inductors to achieve differential signal output, the design of this invention utilizes the interconnection of the gates and drains of two transistors to force the drain voltage swings of the two transistors to be consistent, avoiding the problem of output swing imbalance caused by inductor mismatch that may occur in traditional differential signal implementations using only cross-coupled inductors.

[0038] Table 1 Performance Summary and Overall Comparison

[0039] As shown in Table 1, the performance summary and overall comparison table demonstrates that the design of this invention utilizes a high-frequency differential-mode impedance peak, achieving an operating frequency several times higher than that of a traditional Hartley oscillator. Furthermore, this design eliminates the need for a tail current source, allowing for a lower supply voltage and eliminating noise from the tail current source, resulting in superior overall performance. Compared to cross-coupled LC oscillators in the same frequency band, this design optimizes the drain-to-gate voltage feedback ratio through a frequency phase tuning module and utilizes a coupling inductor to achieve a resonant cavity with a higher quality factor, resulting in overall performance 3.5~4.6 dB better than cross-coupled LC oscillators in the same frequency band.

Claims

1. A differential Hartley oscillator, characterized in that, Includes an equal-amplitude differential drive module and an equal-amplitude differential resonant cavity. The equal amplitude differential driving module is used to generate a differential current signal of equal amplitude; the equal amplitude differential driving module is connected to the equal amplitude differential resonant cavity through a first current signal terminal and a second current signal terminal, and provides a differential current signal of equal amplitude to the equal amplitude differential resonant cavity. The equal-amplitude differential resonant cavity is connected to the equal-amplitude differential drive module through a first voltage signal terminal and a second voltage signal terminal, wherein the first current signal terminal is connected to the second voltage signal terminal, and the second current signal terminal is connected to the first voltage signal terminal; The equal-amplitude differential resonant cavity includes multiple inductors and multiple capacitors. Based on the coupling effect of paired inductors and the synergistic effect of frequency and phase tuning of capacitors, the equal-amplitude differential resonant cavity has two differential-mode impedance peaks. The equal-amplitude differential resonant cavity operates at the differential-mode impedance peak at a high operating frequency. Thus, the equal-amplitude differential resonant cavity in operating mode is used to convert the equal-amplitude differential current signal into an equal-amplitude differential voltage signal, and to input the equal-amplitude differential voltage signal into the equal-amplitude differential drive module.

2. The differential Hartley oscillator according to claim 1, characterized in that, The equal-amplitude differential resonant cavity includes a coupling induction module and a frequency and phase tuning module. The coupling sensing module includes multiple inductors, which are used to make the output signal of the equal amplitude differential resonant cavity a differential voltage signal of equal amplitude through the coupling effect between their own inductors. The frequency phase tuning module includes multiple capacitors, which are used to tune the frequency of the equal-amplitude differential voltage signal output by the coupling sensing module by adjusting the capacitance value, and to tune the phase of the signal fed back to the coupling sensing module by adjusting the capacitance value.

3. The differential Hartley oscillator according to claim 2, characterized in that, The frequency and phase tuning module includes a first capacitor C. D1 First frequency tuning branch, second capacitor C D2 The second frequency tuning branch, the first capacitor C D1 One end is connected to the first current signal terminal, and the first capacitor C D1 The other end is connected to one end of the first frequency tuning branch, and the other end of the first frequency tuning branch is connected to the first voltage signal terminal. The second capacitor C D2 One end of the capacitor is connected to the second current signal terminal, and the second capacitor C D2 The other end is connected to one end of the second frequency tuning branch, and the other end of the second frequency tuning branch is connected to the second voltage signal terminal; The first frequency tuning branch includes a first switched capacitor array for coarse tuning of the operating frequency and a first variable capacitor array for fine tuning of the operating frequency, which are connected in parallel. The second frequency tuning branch includes a second switched capacitor array for coarse tuning of the operating frequency and a second variable capacitor array for fine tuning of the operating frequency, which are connected in parallel.

4. The differential Hartley oscillator according to claim 3, characterized in that, The frequency phase tuning module also includes a third variable capacitor array for fine tuning of the operating frequency. One end of the third variable capacitor array is connected to the first voltage signal terminal, and the other end of the third variable capacitor array is connected to the second voltage signal terminal.

5. The differential Hartley oscillator according to claim 2, characterized in that, The frequency and phase tuning module includes a first capacitor C. D1 A first switched capacitor array used to achieve coarse tuning of the operating frequency, and a second capacitor C. D2 A second switched capacitor array for coarse tuning of the operating frequency and a third variable capacitor array for fine tuning of the operating frequency, wherein the first capacitor C D1 One end is connected to the first current signal terminal, and the first capacitor C D1 The other end is connected to one end of the first switched capacitor array, and the other end of the first switched capacitor array is connected to the first voltage signal terminal. The second capacitor C D2 One end of the capacitor is connected to the second current signal terminal, and the second capacitor C D2 One end of the third variable capacitor array is connected to one end of the second switched capacitor array, and the other end of the second switched capacitor array is connected to the second voltage signal terminal; one end of the third variable capacitor array is connected to the first voltage signal terminal, and the other end of the third variable capacitor array is connected to the second voltage signal terminal.

6. The differential Hartley oscillator according to claim 3 or 5, characterized in that, The frequency phase tuning module also includes a third capacitor C connected in series. D3 and the fourth capacitor C D4 The third capacitor C D3 The other end is connected to the first voltage signal terminal, and the fourth capacitor C D4 The other end is connected to the second voltage signal terminal.

7. The differential Hartley oscillator according to claim 3 or 5, characterized in that, The first switched capacitor array includes multiple first switched capacitor series modules connected in parallel, wherein each first switched capacitor series module includes a fifth capacitor C connected in series sequentially. SCA1 First switch SW1 and sixth capacitor C SCA2 The fifth capacitor C SCA1 The other end is connected to the first capacitor C D1 Connection, sixth capacitor C SCA2 The other end is connected to the first voltage signal terminal; the second switched capacitor array includes multiple parallel second switched capacitor series modules, wherein each second switched capacitor series module includes a seventh capacitor C connected in series sequentially. SCA3 The second switch SW2 and the eighth capacitor C SCA4 The seventh capacitor C SCA3 The other end is connected to the second capacitor C D2 Connection, eighth capacitor C SCA4 The other end is connected to the second voltage signal terminal; The first variable capacitor array includes a first variable capacitor C connected in series. var1 Second variable capacitor C var2 The first variable capacitor C var1 Second variable capacitor C var2 The connection point with the first control voltage V CTRL1 Connection, first variable capacitor C var1 The other end is connected to the first capacitor C D1 Connection, second variable capacitor C var2 The other end is connected to the first voltage signal terminal; The second variable capacitor array includes a third variable capacitor C connected in series. var3 and the fourth variable capacitor C var4 The third variable capacitor C var3 and the fourth variable capacitor C var4 The connection point with the second control voltage V CTRL2 Connection, third variable capacitor C var3 The other end is connected to the second capacitor C D2 Connection, fourth variable capacitor C var4 The other end is connected to the second voltage signal terminal.

8. The differential Hartley oscillator according to claim 4 or 5, characterized in that, The third variable capacitor array includes a fifth variable capacitor C connected in series. var5 and the sixth variable capacitor C var6 The fifth variable capacitor C var5 and the sixth variable capacitor C var6 The connection point and the third control voltage V CTRL3 Connection, fifth variable capacitor C var5 The other end is connected to the first voltage signal terminal, and the sixth variable capacitor C var6 The other end is connected to the second voltage signal terminal.

9. The differential Hartley oscillator according to claim 3, characterized in that, The coupling sensing module includes a first inductor L1, a second inductor L2, a third inductor L3, and a fourth inductor L4. The first inductor L1 and the fourth inductor L4 are mutually inductively coupled, and the second inductor L2 and the third inductor L3 are also mutually inductively coupled. The terminals of the first inductor L1 and the second inductor L2 are connected to the power supply; the terminal of the first inductor L1 with the opposite name is connected to the first current signal terminal; and the terminal of the second inductor L2 with the opposite name is connected to the second current signal terminal. The terminal of the third inductor L3 with the same name is connected to the first capacitor C. D1 The connection point between the first frequency tuning branch and the second current signal branch is connected; the opposite-named terminal of the third inductor L3 is connected to the second current signal terminal; the same-named terminal of the fourth inductor L4 is connected to the first capacitor C. D2 The connection point between the second frequency tuning branch and the fourth inductor L4 is connected to the first current signal terminal.

10. The differential Hartley oscillator according to claim 1, characterized in that, The equal amplitude differential driving module includes a first transistor M1 and a second transistor M2; The sources of both the first transistor M1 and the second transistor M2 are grounded; The drain of the first transistor M1 serves as the first current signal terminal, and the drain of the second transistor M2 serves as the second current signal terminal. The current signal output from the first current signal terminal and the current signal output from the second current signal terminal constitute the equal-amplitude differential current signal. The gate of the first transistor M1 serves as the first voltage signal terminal, and the gate of the second transistor M2 serves as the second voltage signal terminal, for inputting the equal amplitude differential voltage signal provided by the equal amplitude differential resonant cavity. The drain of the first transistor M1 is connected to the gate of the second transistor M2, and the drain of the second transistor M2 is connected to the gate of the first transistor M1.

Images