800MHz frequency band frequency modulation voltage-controlled resonance circuit

Abstract

The utility model discloses a 800MHz frequency band frequency modulation voltage-controlled resonance circuit which mainly comprises a power supply input, a frequency modulation circuit, an LC resonance circuit and an oscillation amplification circuit. The power supply input part provides direct-current voltage for normal working of the circuit, and the frequency modulation circuit reversely biases the variable capacitance diode VD1 by inputting control voltage VA, so that the junction capacitance of the variable capacitance diode VD1 is changed, and frequency tuning of the LC resonance circuit is realized. The LC resonance circuit uses variable capacitance diodes VD2 to VD5 to be matched with a resonance element to form a tunable oscillation loop, and can resonate within the frequency band of 800 MHz to 850 MHz within the range of input voltage VA. The oscillation amplifying circuit amplifies and outputs oscillation signals of the LC resonance circuit through a junction field effect transistor VT1 so as to stably output high-frequency signals with specified frequency. The 800MHz frequency modulation antenna is simple in structure and accurate in frequency tuning, and is suitable for a frequency modulation communication system and radio frequency equipment in the 800MHz frequency band.

Description

Technical Field

[0001] This utility model relates to the field of communications, and in particular to an 800MHz frequency band frequency-modulated voltage-controlled resonant circuit. Background Technology

[0002] In wireless communication systems, the voltage-controlled oscillator (VCO) is a critical component, its performance directly affecting the frequency stability and modulation effect of the communication signal. Existing 800MHz band frequency-modulated VCO resonant circuits typically consist of complex LC resonant circuits, frequency modulation circuits, and amplifier circuits. While these circuit designs can meet the oscillation frequency requirements, their complexity and large number of components lead to high costs and low reliability. Furthermore, the use of bulky components in existing circuits results in significant space requirements in integrated designs, making it difficult to meet the miniaturization and lightweight requirements of modern communication equipment.

[0003] Furthermore, existing frequency-modulated voltage-controlled resonant circuits also have certain limitations in terms of frequency adjustment range, frequency stability, and power consumption. For example, the frequency modulation range is usually limited by the junction capacitance variation range of the varactor diode, while the noise performance of the amplifier circuit limits the purity of the output signal. These shortcomings affect the widespread application of the circuit in high-performance wireless communication equipment. Therefore, there is an urgent need for a simple, high-performance, low-cost, and highly reliable 800MHz band frequency-modulated voltage-controlled resonant circuit to solve the above problems and meet the needs of modern communication technology development. Summary of the Invention

[0004] In view of the problems existing in the prior art, this utility model provides an 800MHz band frequency-modulated voltage-controlled resonant circuit to solve the problems existing in the prior art. The specific technical solution is: an 800MHz band frequency-modulated voltage-controlled resonant circuit, including a power input, a frequency modulation circuit, an LC resonant circuit, and an oscillation amplifier circuit. The power input includes VCC and VCC-E, which are the main power supply voltage and the input control voltage, respectively. The power input terminal VCC is connected to both the frequency modulation circuit and the oscillation amplifier circuit, and the power input terminal VCC-E is connected to the oscillation amplifier circuit. The frequency modulation circuit is used to change the junction capacitance of the varactor diode through the tuning voltage to achieve flexible frequency adjustment. The LC resonant circuit is used to generate and stabilize the resonant frequency, providing a high-purity signal source. The oscillation amplifier circuit is used to amplify the signal, enhance its intensity, and suppress noise. Outputs a high-quality signal; the frequency modulation circuit includes resistors R1, R2, R3, and R4, a varactor diode VD1, capacitors C1 and C4; the power input terminal VCC is connected to one end of resistor R1, one end of resistor R2 is connected to the input signal VA, the other end of resistor R2 is connected to the other end of resistor R1, one end of resistor R3, and one end of resistor R4, the other end of resistor R4 is grounded, the other end of resistor R3 is connected to the cathode of varactor diode VD1 and one end of capacitor C1, the anode of varactor diode VD1 is grounded, the other end of capacitor C1 is connected to one end of capacitor C4, and the other end of capacitor C4 is connected to one end of inductor L4 of the LC resonant circuit and the oscillation... The amplifier circuit includes one end of inductor L1, capacitor C3, and capacitor C9, and the drain (D) of junction field-effect transistor VT1. The LC resonant circuit includes capacitors C2, C5, C7, C8, and C11, varactor diodes VD2, VD3, VD4, and VD5, and inductors L3, L4, and L5. Specifically, one end of inductor L3 is connected to the input voltage VB and one end of capacitor C7, the other end of capacitor C7 is grounded, and the other end of inductor L3 is connected to the cathodes of varactor diodes VD2, VD3, VD4, and VD5, respectively. The negative terminal of 5 is connected, the positive terminals of varactor diodes VD4 and VD5 are grounded, the positive terminals of varactor diodes VD2 and VD3 are connected to one end of inductor L5, one end of capacitor C2 and one end of capacitor C5 respectively, the other end of inductor L5 is grounded, the other ends of capacitors C2 and C5 are connected to one end of capacitor C8 and one end of inductor L4 respectively, the other end of capacitor C8 is connected to one end of capacitor C11, the other end of capacitor C11 is grounded, the other end of inductor L4 is connected to one end of capacitor C4 in the frequency modulation circuit, one end of inductor L1, capacitor C3, capacitor C9 in the oscillation amplifier circuit, and the drain terminal of VT1 respectively;The oscillation amplifier circuit includes resistors R5, R6, and R7; capacitors C3, C6, C9, and C10; inductors L1 and L2; and a junction field-effect transistor (JFET) VT1. The power input terminal VCC is connected to one end of resistor R5. The other end of resistor R5 is connected to one end of inductor L1. The other end of inductor L1 is connected to capacitor C4 in the frequency modulation circuit and inductor L4 in the LC oscillation circuit, and is also connected to one end of capacitors C3 and C9, and the drain (D) terminal of JFET VT1. The other end of capacitor C9 is grounded. The other end of capacitor C3 is connected to one end of inductors L2, C6, and C10, and the source (S) terminal of JFET VT1. The other end of inductor L2 is connected to one end of resistor R6. The other end of resistor R6 is connected to the power supply VCC-E. The other end of capacitor C6 is connected to one end of resistor R7. The other end of capacitor C10 is grounded. The other end of resistor R7 is connected to the output terminal VC. The gate (G) terminal of JFET VT1 is grounded.

[0005] This utility model has the following technical effects:

[0006] This invention provides an 800MHz frequency band voltage-controlled resonant circuit with advantages of simple structure, low cost, and reliable performance. Through optimized design of the frequency modulation circuit, LC resonant circuit, and oscillation amplifier circuit, this circuit achieves stable oscillation output within the frequency range of 800MHz to 850MHz. Utilizing the junction capacitance characteristics of the varactor diode, the oscillation frequency is effectively controlled by the tuning voltage, thereby achieving flexible frequency adjustment and efficient signal modulation.

[0007] This circuit not only reduces the number of components used, lowering design complexity and manufacturing costs, but its miniaturized design also better suits the compactness and integration requirements of modern communication equipment. Furthermore, the circuit exhibits excellent frequency stability and low power consumption, providing a high-quality frequency source for wireless communication and making it suitable for various applications, such as wireless transmission and RF front-end modules. In summary, this technology effectively overcomes the problems of high cost, large size, and limited frequency adjustment range in existing technologies, demonstrating significant practical value. Attached Figure Description

[0008] Figure 1 This is the circuit schematic diagram of this utility model. Detailed Implementation

[0009] The present invention will be further described below with reference to the accompanying drawings:

[0010] like Figure 1As shown, an 800MHz frequency band frequency-modulated voltage-controlled resonant circuit includes a power input, a frequency modulation circuit, an LC resonant circuit, and an oscillation amplifier circuit. The power input includes VCC and VCC-E, which are the main supply voltage and input control voltage, respectively. The power input terminal VCC is connected to both the frequency modulation circuit and the oscillation amplifier circuit, while the power input terminal VCC-E is connected to the oscillation amplifier circuit, providing the voltage required for normal operation. The frequency modulation circuit is used to change the junction capacitance of the varactor diode through the tuning voltage, achieving flexible frequency adjustment. The LC resonant circuit is used to generate and stabilize the resonant frequency, providing a high-purity signal source. The oscillation amplifier circuit amplifies the signal, enhances its intensity, suppresses noise, and outputs a high-quality signal.

[0011] The frequency modulation circuit includes resistors R1, R2, R3, and R4, a varactor diode VD1, and capacitors C1 and C4. The varactor diode VD1 selected for the frequency modulation circuit is model BBY55-02V. The power input terminal VCC is connected to one end of resistor R1. One end of resistor R2 is connected to the input signal VA. The other end of resistor R2 is connected to the other end of resistor R1, one end of resistor R3, and one end of resistor R4. The other end of resistor R4 is grounded. The other end of resistor R3 is connected to the cathode of varactor diode VD1 and one end of capacitor C1. The anode of varactor diode VD1 is grounded. The other end of capacitor C1 is connected to one end of capacitor C4. The other end of capacitor C4 is connected to one end of inductor L4 in the LC resonant circuit, one end of inductor L1 in the oscillation amplifier circuit, one end of capacitor C3 and one end of capacitor C9, and the drain of junction field-effect transistor VT1.

[0012] The LC resonant circuit includes capacitors C2, C5, C7, C8, and C11; varactor diodes VD2, VD3, VD4, and VD5; and inductors L3, L4, and L5. Specifically, one end of inductor L3 is connected to the input voltage VB and one end of capacitor C7. The other end of capacitor C7 is grounded. The other end of inductor L3 is connected to the cathodes of varactor diodes VD4, VD5, VD2, and VD3, respectively. The anode of varactor diode VD4 is connected to... The positive terminal of varactor diode VD5 is grounded. The positive terminals of varactor diodes VD2 and VD3 are connected to one end of inductor L5, capacitor C2, and one end of capacitor C5, respectively. The other end of inductor L5 is grounded. The other ends of capacitors C2 and C5 are connected to one end of capacitor C8 and one end of inductor L4, respectively. The other end of capacitor C8 is connected to one end of capacitor C11. The other end of capacitor C11 is grounded. The other end of inductor L4 is connected to one end of capacitor C4 in the frequency modulation circuit, one end of inductor L1, capacitor C3, and capacitor C9 in the oscillation amplifier circuit, and the drain terminal of VT1, respectively.

[0013] The oscillation amplifier circuit includes resistors R5, R6, and R7; capacitors C3, C6, C9, and C10; inductors L1 and L2; and a junction field-effect transistor (JFET) VT1. The selected JFET is model MCH3914-7-TL-H. The power input terminal VCC is connected to one end of resistor R5, and the other end of resistor R5 is connected to one end of inductor L1. The other end of inductor L1 is connected to capacitor C4 in the frequency modulation circuit and inductor L4 in the LC oscillation circuit, and is also connected to... One end of capacitor C3 and capacitor C9 is connected to the drain (D) terminal of junction field-effect transistor VT1. The other end of capacitor C9 is grounded. The other end of capacitor C3 is connected to one end of inductor L2, capacitor C6, capacitor C10, and the source (S) terminal of VT1. The other end of inductor L2 is connected to one end of resistor R6. The other end of resistor R6 is connected to power supply VCC-E. The other end of capacitor C6 is connected to one end of resistor R7. The other end of capacitor C10 is grounded. The other end of resistor R7 is connected to the output terminal VC. The gate (G) terminal of VT1 is grounded.

[0014] The working principle of this utility model:

[0015] The working principle of an LC resonant circuit: When a DC voltage of 1V to 4V is applied to the input terminal VA (tuning interface), the capacitance value of the varactor diode changes with the reverse voltage. The varactor diodes (VD2, VD3, VD4, VD5) generate different junction capacitance values ​​under different reverse voltage conditions. These junction capacitances, along with the inductors (L3, L4, L5) and capacitors (C2, C5, C7, etc.) of the LC resonant circuit, form a resonant circuit. When the junction capacitance of the varactor diodes in the resonant circuit changes, the resonant frequency of the LC resonant circuit also changes, thereby adjusting the frequency of the oscillation signal. Specifically, when the junction capacitance of the varactor diodes increases, the resonant frequency of the LC circuit decreases; conversely, when the junction capacitance decreases, the resonant frequency increases. This change causes the oscillation frequency to fluctuate within a certain range with changes in the input regulating voltage, ensuring that the oscillation frequency can be precisely controlled within the range of 800MHz to 850MHz under different regulating voltages.

[0016] Frequency modulation (FM) working principle: When the input signal VA generates different voltages in the FM circuit, the voltage divider via resistors R1 and R4, and the adjustment via resistors R2 and R3, generate an input signal of appropriate amplitude to affect the capacitance change of the varactor diode VD1. Different input voltage amplitudes cause changes in the junction capacitance of VD1, thereby fine-tuning the offset of the oscillation frequency. This fine-tuning allows the signal frequency to vary within a given range, thus achieving frequency modulation. This frequency modulation method ensures that the output signal varies within a certain frequency range, making it adaptable to different application requirements.

[0017] The working principle of the oscillation amplifier circuit: The main function of the oscillation amplifier circuit is to provide energy to the front-end LC resonant circuit through positive feedback, enabling it to oscillate stably and increasing the output frequency amplitude. Specifically, the oscillation signal is amplified through a junction field-effect transistor (VT1). The source (S) of the VT1 is connected to the power supply VCC-E, the drain (D) is connected to the output terminal VC, and the gate (G) is grounded. The inductors L1 and L2, as well as capacitors C3, C9, and C10 in this circuit work together to ensure stable signal amplification and eliminate high-frequency interference.

[0018] Finally, the signal is output at the VC terminal, becoming a frequency-modulated signal that can be used for transmission. This signal serves as the frequency input for subsequent circuits, completing the work of frequency-modulated voltage-controlled oscillation.

Claims

1. An 800MHz frequency band frequency-modulated voltage-controlled resonant circuit, characterized in that: The system includes a power input, a frequency modulation circuit, an LC resonant circuit, and an oscillation amplifier circuit. The power input includes VCC and VCC-E, which are the main power supply voltage and input control voltage, respectively. The power input terminal VCC is connected to both the frequency modulation circuit and the oscillation amplifier circuit, while the power input terminal VCC-E is connected to the oscillation amplifier circuit. The frequency modulation circuit is used to change the junction capacitance of the varactor diode by adjusting the tuning voltage, thus achieving flexible frequency adjustment. The LC resonant circuit is used to generate and stabilize the resonant frequency, providing a high-purity signal source. The oscillation amplifier circuit amplifies the signal, enhances its intensity, suppresses noise, and outputs a high-quality signal. The frequency modulation circuit includes resistors R1, R2, and R3. The circuit consists of resistor R4, varactor diode VD1, capacitor C1, and capacitor C4. The power input terminal VCC is connected to one end of resistor R1. One end of resistor R2 is connected to the input signal VA. The other end of resistor R2 is connected to the other end of resistor R1, one end of resistor R3, and one end of resistor R4. The other end of resistor R4 is grounded. The other end of resistor R3 is connected to the cathode of varactor diode VD1 and one end of capacitor C1. The anode of varactor diode VD1 is grounded. The other end of capacitor C1 is connected to one end of capacitor C4. The other end of capacitor C4 is connected to one end of inductor L4 in the LC resonant circuit, one end of inductor L1 in the oscillation amplifier circuit, one end of capacitor C3, one end of capacitor C9, and the drain of junction field-effect transistor VT1. The LC resonant circuit... The resonant circuit includes capacitors C2, C5, C7, C8, and C11; varactor diodes VD2, VD3, VD4, and VD5; and inductors L3, L4, and L5. Specifically, one end of inductor L3 is connected to the input voltage VB and one end of capacitor C7. The other end of capacitor C7 is grounded. The other end of inductor L3 is connected to the negative terminals of varactor diodes VD2, VD3, VD4, and VD5, respectively. The positive terminals of varactor diodes VD4 and VD5 are grounded. The positive terminal of varactor diode VD2 is connected to varactor diode VD3. After the positive terminal is connected, it is connected to one end of inductor L5, capacitor C2 and one end of capacitor C5 respectively. The other end of inductor L5 is grounded. After the other ends of capacitor C2 and capacitor C5 are connected, they are connected to one end of capacitor C8 and one end of inductor L4 respectively. The other end of capacitor C8 is connected to one end of capacitor C11. The other end of capacitor C11 is grounded. The other end of inductor L4 is connected to one end of capacitor C4 in the frequency modulation circuit, one end of inductor L1, capacitor C3, capacitor C9 in the oscillation amplifier circuit, and the drain terminal of VT1 respectively. The oscillation amplifier circuit includes resistor R5, resistor R6, resistor R7, capacitor C3, capacitor C6, capacitor C9, capacitor C10, inductor L1, inductor L2 and junction field-effect transistor VT1. The power input terminal VCC is connected to one end of the circuit resistor R5. The other end of the resistor R5 is connected to one end of the inductor L1. The other end of the inductor L1 is connected to the frequency modulation circuit capacitor C4 and the LC oscillation circuit inductor L4, and is connected to one end of capacitor C3 and capacitor C9, and the drain of the junction field-effect transistor VT1, respectively. The other end of capacitor C9 is grounded. The other end of capacitor C3 is connected to one end of inductor L2, capacitor C6, capacitor C10, and the source of the field-effect transistor VT1, respectively. The other end of inductor L2 is connected to one end of resistor R6. The other end of resistor R6 is connected to the power supply VCC-E. The other end of capacitor C6 is connected to one end of resistor R7. The other end of capacitor C10 is grounded. The other end of resistor R7 is connected to the output terminal VC. The gate of the field-effect transistor VT1 is grounded.

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