RU149143U1 - FREQUENCY-MODULATED PULSES GENERATOR - Google Patents

Abstract

1. The generator of frequency-modulated pulses containing two logic elements NOT (3) and (4), a resistor (6), a resistor (7), a capacitor (9), characterized in that the logic elements 2 OR NOT (1) are introduced into it ), NOT (2), NOT (5), a buffer logic element (11) consisting of two series-connected inverters, a capacitor (8), a MOS transistor (10) with an induced n-type channel, the frequency modulation is carried out by changing the resistance of the channel of the MOS transistor under the action of a control voltage supplied to its gate, the generator is turned on leveling voltage (12), while the output of the logic element (1) is connected to the input of the logic element (2), the output of the logic element (2) is connected to the input of the logic element (3), the output of the logic element (3) is connected to the input of the logic element ( 4) and the first output of the resistor (6), the output of the logic element (4) is connected to the input of the logic element (5), the output of the logic element (5) is connected to the input of the buffer logic element (11), the first output of the capacitor (9) and the second input logic element (1), the first input of logic element (1) is the input of the generator enable signal, which in a particular case is connected to the common power output of the frequency-modulated pulse generator, the output of the buffer logic element (11) is the output of the frequency-modulated pulse generator, the second output of the capacitor (9) is connected to the first output of the resistor (7 ) and the drain of the MOS transistor (10) with an induced n-type channel, the substrate of the MOS transistor (10) is connected to the common bus of the pulse generator, the gate of the MOS transistor (10) is connected to the output of the control voltage generator

Description

The utility model relates to the field of radio engineering and can be used in radio transmitting devices, in measuring equipment as a source of pulses modulated in frequency.

Achievable technical result - expanding the functionality of the pulse generator.

Known pulse generator containing the first logic element is NOT (1), the second logic element is NOT (2), a capacitor, two constant resistors, one variable resistor, the logic element is NOT (3) (Fig. 1) [1].

The disadvantage of this known device is that with selected logic elements and given values of the capacitor capacitance and resistor resistances, the device generates rectangular pulses only at a fixed frequency. This device does not carry out an automated change in the pulse repetition rate. In principle, this device cannot carry out any modulation of the generated pulse sequence.

The purpose of the claimed technical solution is to expand the operational capabilities of the device.

The technical result of this utility model achieved is the expansion of the functionality of the pulse generator, which consists in providing a sequence of generated pulses modulated in frequency.

The frequency-modulated pulse generator (Fig. 2) contains a logical element 2OR-NOT (1), logical elements NOT (2), (3), (4), (5), a buffer logic element (11), consisting of two in series included inverters, two constant resistors (6), (7), two capacitors (8), (9), a MOS transistor (10) with an induced channel, an external control voltage generator (12).

The technical result is achieved by introducing a MOS transistor (10) with an induced n-type channel; frequency modulation is carried out by changing the channel resistance of the MOS transistor under the action of a control voltage supplied to its gate. The output of logic element (1) is connected to the input of logic element (2), the output of logic element (2) is connected to the input of logic element (3), the output of logic element (3) is connected to the input of logic element (4) and the first output of resistor (6 ), the output of the logic element (4) is connected to the input of the logic element (5), the output of the logic element (5) is connected to the input of the buffer logic element (11), the first output of the capacitor (9) and the second input of the logic element (1), the first input logic element (1) is an enable signal input the operation of the generator, which in a particular case is connected to a common output terminal of the frequency-modulated pulse generator, the output of the buffer logic element (11) is the output of the frequency-modulated pulse generator, the second terminal of the capacitor (9) is connected to the first terminal of the resistor (7) and the drain (10) with an n-type induced channel, the substrate of the MOS transistor (10) is connected to the common bus of the pulse generator, the gate of the MOS transistor (10) is connected to the output of the control voltage generator (12), the second output of the resistor (7) is connected to the second terminal of the resistor (6) and the first terminal of the capacitor (8), the second terminal of the latter is connected to the source of the MOS transistor (10) and the common bus of the pulse generator.

The device "Generator of frequency-modulated pulses" works as follows. The 2OR-NOT logic element (1) allows the device to operate, inverters (3) and (4) have a large signal delay due to the increased length of the transistor channels, inverters (2) and (5) are used to align the signal edges, the output buffer (11 ) is intended to form a sharp edge of the output signal.

Excitation of pulse generation. The first output of the logic element (1) is connected to the point of zero potential of the device. At the first moment after turning on the DC source at the second output of the logic element (1), the voltage is zero. Logic element (1) is 2 OR NOT, therefore, at the output of logic element (1) there will be a voltage of a logical unit. This provides a logic zero level at the output of logic element (2), a logic level at the output of logic element (3), a logic zero level at the output of logic element (4), and a logic level at the output of logic element (5), which the input of the logical element (1) will provide the next state transition from 1 to 0 at the output of the logical element (1), etc.

The mechanism for generating frequency-modulated pulses. The circuit, consisting of the resistance of the MOS transistor (10) and the resistance of the resistor (7) connected in parallel with the alternating current, is characterized by the equivalent resistance value R _equiv . The circuit, consisting of a series-connected capacitor (9), the equivalent resistance R _equiv and the resistance of the resistor (6), is a feedback circuit supplying a signal from the output of the logic element (5) to its input of the logic element (4). The control voltage of the external generator (12) acts on the gate of the MOS transistor (10), changes the channel resistance of the MOS transistor (10), therefore, the equivalent resistance R _equiv . This entails a change in the feedback loop time constant.

which leads to a change in the frequency of pulse generation. So, the frequency of the generated pulsed oscillations varies according to the law of the control signal, the sequence of pulses at the output of the device is modulated in frequency.

The simulation of the frequency-modulated pulse generator showed that when the voltage of the control signal is varied from 0 V to +3.3 V, the frequency of the generated pulses changes from 43.317 MHz to 107.712 MHz. In this case, the amplitude of the pulse sequence is equal to the voltage of the power source of the frequency-modulated oscillation generator 3.3 V. The output buffer, composed of two logical elements NOT, provides an improvement in the shape (edge steepness) of the generated pulses.

When replacing an MOSFET (10) with an induced n-channel with a MOSFET with an induced p-channel (Fig. 3), the substrate of the MOSFET (10) is connected to the positive terminal of the pulse generator power supply, the gate of the MOSFET (10) connected to the output of the control voltage generator (12), the second terminal of the resistor (7) is connected to the second terminal of the resistor 6 and to the first terminal of the capacitor (8), the second terminal of the latter is connected to the source of the MOS transistor (10) and the positive terminal of the pulse generator power supply . This ensures the use of the inverse signal of the external control generator (12) due to the fact that the MOS transistor with the induced p-channel opens when | U _gene |> | U for the _{time being} | MOSFET (10).

Literature

1. Yu. Vinogradov “Are mosquitoes so afraid of ultrasound?”. The magazine "Radio", No. 7, 1994. - S. 25.

Claims (2)

1. The generator of frequency-modulated pulses containing two logic elements NOT (3) and (4), a resistor (6), a resistor (7), a capacitor (9), characterized in that the logic elements 2 OR NOT (1) are introduced into it ), NOT (2), NOT (5), a buffer logic element (11) consisting of two series-connected inverters, a capacitor (8), a MOS transistor (10) with an induced n-type channel, the frequency modulation is carried out by changing the resistance of the channel of the MOS transistor under the action of a control voltage supplied to its gate, the generator leveling voltage (12), while the output of the logic element (1) is connected to the input of the logic element (2), the output of the logic element (2) is connected to the input of the logic element (3), the output of the logic element (3) is connected to the input of the logic element ( 4) and the first output of the resistor (6), the output of the logic element (4) is connected to the input of the logic element (5), the output of the logic element (5) is connected to the input of the buffer logic element (11), the first output of the capacitor (9) and the second input logic element (1), the first input of logic element (1) is the input of the generator enable signal, which in a particular case is connected to the common power output of the frequency-modulated pulse generator, the output of the buffer logic element (11) is the output of the frequency-modulated pulse generator, the second output of the capacitor (9) is connected to the first output of the resistor (7 ) and the drain of the MOS transistor (10) with an induced n-type channel, the substrate of the MOS transistor (10) is connected to the common bus of the pulse generator, the gate of the MOS transistor (10) is connected to the output of the control voltage generator (12), the second terminal of the resistor (7) is connected to the second terminal of the resistor (6) and to the first terminal of the capacitor (8), the second terminal of the latter is connected to the source of the MOS transistor (10) and the common bus of the pulse generator. 2. The frequency-modulated pulse generator according to claim 1, characterized in that a MOS transistor (10) with an induced p-type channel is inserted into it, the substrate of the MOS transistor (10) is connected to the positive terminal of the pulse generator power source, the MOS gate the transistor (10) is connected to the output of the control voltage generator (12), the second terminal of the resistor (7) is connected to the second terminal of the resistor (6) and to the first terminal of the capacitor (8), the second terminal of the latter is connected to the source of the MOS transistor (10) and the positive output of the generator power supply and pulses.

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