Frequency pulse width modulation circuit

Abstract

The utility model discloses a frequency pulse width modulation circuit, comprising an oscillation circuit used for generating a periodic waveform signal; the comparison circuit is connected with the oscillating circuit and is used for receiving the waveform signal, comparing the waveform signal with a preset reference signal and generating a modulation signal; and the pulse shaping output circuit is connected with the comparison circuit and is used for receiving the modulation signal and shaping the modulation signal into a pulse output signal with a fixed duty ratio. According to the utility model, through the simple combination of the resistor, the capacitor, the operational amplifier and other elements, accurate control of output frequency and duty ratio can be realized through fine tuning, the difficulty of circuit design and use is reduced, and the application range is expanded.

Description

Technical Field

[0001] The utility model relates to a circuit, in particular to a frequency pulse width modulation circuit. Background Art

[0002] With the development of electronic technology, frequency pulse width modulation (PWM) technology is widely used in fields such as signal processing, control systems, and power regulation. In the prior art, frequency pulse width modulation circuits are often implemented through complex control systems, including components such as single-chip microcomputer control, key input, and display screens. Although these systems are powerful in function, they are complex in design, high in usage cost, and not suitable for the requirements of simple application scenarios, such as experimental teaching, DIY projects, and control systems of mid- to low-end devices.

[0003] There are some deficiencies in the design of existing frequency pulse width modulation circuits, for example:

[0004] Many existing solutions require single-chip microcomputer programming and complex control circuits, increasing the difficulty of design and maintenance, and having relatively high technical requirements for users, which are not suitable for beginners or occasions that require simple adjustment.

[0005] Existing PWM circuits often lack simple and accurate adjustment means, and it is difficult to finely adjust the output frequency and pulse width without changing the hardware configuration, restricting their scope of application.

[0006] Frequency pulse width modulation circuits using complex control systems are relatively high in manufacturing cost and maintenance cost, and are difficult to be applied to low-cost devices. Summary of the Invention

[0007] To solve the above problems, the utility model provides a frequency pulse width modulation circuit with easily adjustable frequency and duty cycle settings, and the circuit design should avoid using complex control systems to reduce costs and improve the convenience of use.

[0008] The utility model is realized through the following technical solutions: a frequency pulse width modulation circuit, comprising:

[0009] An oscillation circuit for generating a periodic waveform signal;

[0010] A comparison circuit connected to the oscillation circuit for receiving the waveform signal and comparing it with a preset reference signal to generate a modulation signal;

[0011] A pulse shaping output circuit connected to the comparison circuit for receiving the modulation signal and shaping the modulation signal into a pulse output signal with a fixed duty cycle.

[0012] Among them, the output end of the oscillation circuit is connected to the input end of the comparison circuit;

[0013] The output end of the comparison circuit is connected to the input end of the pulse shaping output circuit.

[0014] As a preferred technical solution, the oscillation circuit includes resistors R2, R3, R9, R7, R5 and capacitor C1. The capacitor C1 and the resistor R7 form an integrating circuit, and the output frequency can be changed by adjusting the capacitance of the capacitor C1.

[0015] As a preferred technical solution, the resistor R9 in the oscillation circuit is used to adjust the period of the output signal.

[0016] As a preferred technical solution, the comparison circuit includes resistors R4, R11, R15 and R5. The resistor R11 is used to adjust the reference voltage value, thereby changing the duty cycle of the output pulse.

[0017] As a preferred technical solution, the resistor R4 and the resistor R11 are connected in series. By adjusting the resistance value of R11, the input voltage of the comparison circuit can be changed.

[0018] As a preferred technical solution, the pulse shaping output circuit includes an operational amplifier U2B and resistors R8, R6. The operational amplifier U2B is used to shape the output signal of the comparison circuit into a square wave pulse signal with a fixed voltage amplitude.

[0019] As a preferred technical solution, the operational amplifier U2B is an operational amplifier of the LM324 type, and its output end is connected to the resistor R8 to generate the pulse signal.

[0020] As a preferred technical solution, it further includes an adjustable potentiometer R11, which is used to finely adjust the reference signal level of the comparison circuit to precisely control the duty cycle of the output pulse.

[0021] The beneficial effects of the present utility model are as follows: The present utility model overcomes the disadvantages of complex modulation and high operation threshold in the prior art, and achieves the purpose of simple circuit design, convenient adjustment and stable performance;

[0022] Through the combination of simple components such as resistors, capacitors and operational amplifiers, this circuit can precisely control the output frequency and duty cycle through fine adjustment, which not only reduces the difficulty of circuit design and use, but also expands the application range;

[0023] This circuit does not require complex single-chip microcomputer programming and display screen operation, greatly reducing the learning cost of beginners, and is particularly suitable for scenarios such as student DIY experiments, temperature control heating devices, and running water lamp devices;

[0024] Due to the adoption of the combination of an integrating circuit and a comparison circuit, the utility model can provide a stable pulse modulation signal in various application scenarios, has strong anti-interference ability and stability, and the circuit has low production cost and is easy to maintain, thus having a wide market application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 Schematic diagram of the working principle of the pulse width modulation circuit of the present utility model;

[0027] Figure 2 Schematic diagram of the frequency pulse width modulation circuit of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] All features disclosed in this specification, or all steps in any method or process disclosed, except for mutually exclusive features and / or steps, can be combined in any manner.

[0029] Any feature disclosed in this specification (including any additional claims, abstract, and drawings), unless specifically stated, can be replaced by other equivalent or similar-purpose alternative features. That is, unless specifically stated, each feature is only an example in a series of equivalent or similar features.

[0030] As Figure 1 and Figure 2 shown, a frequency pulse width modulation circuit of the present utility model includes an oscillation circuit for generating a periodic waveform signal;

[0031] A comparison circuit, connected to the oscillation circuit, for receiving the waveform signal and comparing it with a preset reference signal to generate a modulation signal;

[0032] A pulse shaping output circuit, connected to the comparison circuit, for receiving the modulation signal and shaping the modulation signal into a pulse output signal with a fixed duty cycle.

[0033] Wherein, the output end of the oscillation circuit is connected to the input end of the comparison circuit;

[0034] The output end of the comparison circuit is connected to the input end of the pulse shaping output circuit.

[0035] As a preferred technical solution, the oscillation circuit includes resistors R2, R3, R9, R7, R5 and capacitor C1. The capacitor C1 and the resistor R7 form an integrating circuit, and the output frequency is changed by adjusting the capacitance of the capacitor C1.

[0036] In this embodiment, the resistor R9 in the oscillation circuit is used to adjust the period of the output signal. The comparison circuit includes resistors R4, R11, R15 and R5. The resistor R11 is used to adjust the reference voltage value, thereby changing the duty cycle of the output pulse; the resistor R4 is connected in series with the resistor R11, and adjusting the resistance value of R11 can change the input voltage of the comparison circuit.

[0037] The pulse shaping output circuit includes operational amplifier U2B and resistors R8, R6. The operational amplifier U2B is used to shape the output signal of the comparison circuit into a square wave pulse signal with a fixed voltage amplitude. The operational amplifier U2B is an operational amplifier of the LM324 type, and its output terminal is connected to the resistor R8 to generate the pulse signal.

[0038] In this embodiment, it further includes an adjustable potentiometer R11, which is used to finely adjust the reference signal level of the comparison circuit to precisely control the duty cycle of the output pulse.

[0039] Specifically, the oscillation circuit is composed of resistors R2, R3, R9, R7, R5 and capacitor C1. The operational amplifier U1B is responsible for amplification and feedback; the capacitor C1 and the resistor R7 form an integrating circuit, and a periodic sawtooth wave signal P1 is generated through the charging and discharging process; by adjusting the capacitance of the capacitor C1, the frequency of the output sawtooth wave signal can be changed, that is, the period of the output signal can be changed.

[0040] The comparison circuit is composed of resistors R4, R11, R15 and operational amplifier U2B. The sawtooth wave signal P1 is input to the positive input terminal of the operational amplifier U2B through the resistor R5, and the reference signal P2 is input to the negative input terminal of the operational amplifier U2B through the resistor R11; the voltage of the reference signal P2 can be finely adjusted by adjusting the resistor R11; the function of the operational amplifier U2B is to compare the sawtooth wave signal P1 with the reference signal P2. When P1 is higher than P2, U2B outputs a high level; when P1 is lower than P2, U2B outputs a low level.

[0041] The pulse shaping output circuit is composed of operational amplifier U2B and resistors R8, R6; this circuit receives the output signal of the comparison circuit and shapes it into a square wave signal with a stable voltage amplitude; through this shaping process, a stable pulse output signal P3 can be obtained, which is suitable for the control of external devices.

[0042] When the sawtooth wave signal P1 generated by the oscillation circuit rises to exceed the reference voltage P2, the output of the comparison circuit switches to a high level, and the pulse shaping output circuit outputs a high level signal P3; when the sawtooth wave signal P1 drops below the reference voltage P2, the output of the comparison circuit switches to a low level, and the pulse shaping output circuit outputs a low level signal P3. In a complete sawtooth wave cycle, P3 will generate a corresponding pulse signal. By adjusting the reference voltage P2 and the parameters of the oscillation circuit, the frequency and duty cycle of the pulse signal can be flexibly controlled.

[0043] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any changes or substitutions that are not conceived through creative work should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope defined in the claims.

Claims

1. A frequency pulse width modulation circuit, characterized in that: include: An oscillating circuit, the oscillating circuit is used to generate a periodic waveform signal; A comparison circuit, connected to the oscillation circuit, for receiving the waveform signal and comparing it with a preset reference signal to generate a modulation signal; A pulse shaping output circuit, the pulse shaping output circuit is connected to the comparison circuit, and is used to receive the modulation signal and shape the modulation signal into a pulse output signal with a fixed duty cycle; Wherein, the output end of the oscillation circuit is connected to the input end of the comparison circuit; The output end of the comparison circuit is connected to the input end of the pulse shaping output circuit.

2. The frequency pulse width modulation circuit according to claim 1, characterized in that: The oscillation circuit includes resistors R2, R3, R9, R7, R5 and a capacitor C1. The capacitor C1 and the resistor R7 form an integration circuit. The output frequency can be changed by adjusting the capacity of the capacitor C1.

3. The frequency pulse width modulation circuit according to claim 1, characterized in that: The resistor R9 in the oscillation circuit is used to adjust the period of the output signal.

4. The frequency pulse width modulation circuit according to claim 1, characterized in that: The comparison circuit includes resistors R4, R11, R15 and R5, and the resistor R11 is used to adjust the reference voltage value, thereby changing the duty cycle of the output pulse.

5. The frequency pulse width modulation circuit according to claim 4, characterized in that: The resistor R4 is connected in series with the resistor R11, and the input voltage of the comparison circuit can be changed by adjusting the resistance value of R11.

6. The frequency pulse width modulation circuit according to claim 1, characterized in that: The pulse shaping output circuit includes an operational amplifier U2B and resistors R8 and R6. The operational amplifier U2B is used to shape the output signal of the comparison circuit into a square wave pulse signal with a fixed voltage amplitude.

7. The frequency pulse width modulation circuit according to claim 6, characterized in that: The operational amplifier U2B is an LM324 operational amplifier, and its output end is connected to the resistor R8 for generating the pulse signal.

8. The frequency pulse width modulation circuit according to claim 1, characterized in that: An adjustable potentiometer R11 is also included for fine-tuning the reference signal level of the comparison circuit to accurately control the duty cycle of the output pulse.

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