SU1205289A1 - Frequency modulator - Google Patents

Description

The invention relates to instrumentation and pulse engineering, to information processing techniques, in particular, to devices for magnetic recording and reproduction of a frequency-modulated signal.

The purpose of the invention is to increase the stability of work and expand its frequency range.

The drawing shows the electrical circuit of the device. The frequency modulator contains a current source 1 that is controlled from the bus 2 of the input voltage on the transistor 3, the base and emitter of which are connected to the first outputs of the first and second resistors 4 and 5, respectively, first and second diodes 6 and 7, the inverter 8, in the feedback circuit of which the second diode 7 is turned on, the input of the inverter 8 is connected via a capacitor 9 to a common power supply bus. The third diode 10, the transistor 3 of the current source 1 is made on a pnp type transistor, the base of which is connected via an anode to a cathode of the first diode 6 and connected to the power supply bus 11 and to the second output of the second resistor 5, the second output of the first resistor 4 is connected to the common The power supply bus, the emitter of transistor 3 is connected to the input bus 2 of the frequency modulator, the output bus 12 of which is connected

Compiled by V. Chizhikov Editor A. Gulko Tehred A. Babinets Corrector V, But ha

Order 8539/58 Circulation 871 Subscription VNIIPI USSR State Committee

for inventions and discoveries 113035. Moscow, Zh-35, Raushsk nab. 4/5

Branch PPP Patent f g, Uzhgorod, ul, Project, 4.

to the output of the inverter 8 and connected through series-connected transitions cathode - anode of the third and second diodes 10 and 1 with the input of the inverter 8,

The frequency modulator operates as follows.

If there is a logic zero at the output of the inverter 8, the capacitor 9 is quickly discharged through the open diodes 7 and 10. When the voltage on the capacitor 9 drops to the trigger threshold of the inverter 8, it switches and the voltage of the logical unit appears at its output. In this case, diodes 7 and 10 are charged and the capacitor 9 is charged with current, proportional to the voltage from bus 2. When the voltage on the capacitor 9 reaches the operating level of the inverter 8, a voltage of zero appears at its output, the diodes 7 and 10 open and the process is repeated.

The stability of the frequency modulator operation is ensured by the linearity and dependence of the source current on the control input voltage. The insertion of the third diode 10 reduces the difference between the upper and lower capacitor charge levels, thereby increasing the range of operation of the frequency modulator.

Claims (1)

A FREQUENCY MODULATOR containing a controlled current source on a transistor, the base and emitter of which is connected to the first terminals of the first and second resistors respectively, the first diode, inverter, in the feedback circuit of which a second diode is connected, the inverter input is connected via a capacitor to the common bus of the power source, characterized in that, in order to increase the stability of work and expand its frequency range, a third diode is introduced in series with the second diode, the base of the transistor of a controlled current source h Through the anode-cathode transition of the first diode is connected to the positive bus of the power source and to the second terminal of the second resistor, the second terminal of the first resistor is connected to the common bus of the power source, the emitter of the transistor is connected to the input bus of the frequency modulator, the output bus, which is connected to the output of the inverter and to cathode of the third diode, the anode of the second diode is connected to the input of the inverter.