Pulse width and duty ratio modulation signal generation circuit and method

Abstract

The invention provides a pulse width and duty ratio modulation signal generation circuit. The pulse width and duty ratio modulation signal generation circuit comprises a high-level modulation circuitand a low-level modulation circuit which are connected to the input end of a trigger, the high-level modulation circuit comprises a first dial switch, a first E2PROM chip and a first subtracter whichare connected in sequence. The low-level modulation circuit comprises a second dial switch, a second E2PROM chip and a second subtracter which are connected in sequence; the dial switch is used for selecting the count value of the E2PROM chip corresponding to the dial switch as an initial value, and the two subtracters alternately and circularly carry out subtraction counting according to the corresponding calculation frequency and the initial value; and the trigger outputs a corresponding PWM signal in the duration of the subtraction number, and overturns when the subtraction number is reduced to zero each time. The high level time and the low level time of the PWM signal can be independently adjusted, the adjustable range is large, a pure digital circuit is adopted, and the generated signal waveform is stable and reliable.

Description

technical field [0001] The invention relates to the field of electronic technology, in particular to a pulse width and duty ratio modulation signal generating circuit and method. Background technique [0002] Pulse width modulation technology (PWM, Pulse width modulation) is widely used in digital control systems such as measurement, communication, and power control and conversion. The adjustable range, and the high and low level time of the signal are independently controlled, so as to realize the control of the opening of the solenoid valve. [0003] At present, pulse width modulation technology usually adopts intelligent control methods such as programmable controllers, which require single-chip microcomputers or other processing chips to control generation. The system is complex and the cost is high. However, the traditional method of using analog circuits to realize triangular wave comparison has poor linearity. The problem of low precision. Contents of the invention...

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Problems solved by technology

[0003] At present, the pulse width modulation technology usually adopts intelligent control methods such as programmable controllers, which need to be controlled by a single-chip microcomputer or other processing chips. The system is complex and the cost is high. However, the traditional method of using analog circuits to realize triangular wave comparison has poor linearity. The problem of low precision

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