SU1288903A1 - Gated threshold device - Google Patents

Abstract

The invention relates to a pulse technique and can be used in instrumentation equipment designed to measure amplitude and time parameters of electrical processes in the nano- and picosecond ranges. The purpose of the invention is to improve the accuracy of operation by ensuring the invariance of the modes of operation of the elements at the time of operation and expanding the dynamic range of the input voltages due to the limitation of the permissible input voltage. To achieve this goal, a device containing a field-effect transistor 1, input bus 2, resistors 3, 5, 7, 8, 9, II, 13, 15, 19, 20 and 21, tunnel diode 6, power source 4, source 10 reference voltage, transistor 12, output bus 14 and 22, generator 4, source. nick 10 of the reference voltage, transistor 12, output buses 14 and 22, gating pulse generator 17, input-input bus 24 Reset, coupling capacitors 16, 18 and 23 are introduced. The introduction of capacitors causes the change in the threshold to be triggered by the threshold device relative to the signal under study, which ensures that the operation modes of all elements of the device are constant at the instant of operation. Due to this, the measurement error of the amplitude parameters is determined only by the noise of the threshold device. 2 Il. (Ls

Description

technology and can be used in instrumentation, designed to measure the amplitude and time parameters of electrical processes in the nano- and picosecond ranges.

The aim of the invention is to increase the accuracy of operation by ensuring the immutability of the modes of operation of the elements at the time of operation and by expanding the dynamic range of the input voltages by limiting the allowable input voltage.

FIG. 1 is a schematic diagram of a gated threshold device; in fig. 2 - timing diagrams for the operation of the device.

The gated threshold device contains a field-effect transistor 1 connected to the input bus 2 by a gate, the source through the first resistor 3 to the minus bus of the power source 4, and the drain through the second resistor 5 to the anode of the tunnel diode 6 and through the third resistor 7 to the positive source bus 4 power connected through the fourth resistor B to the anode of the tunnel diode 6, the cathode of which is connected through the fifth resistor 9 to the minus bus of the power source 4 connected to the first output of the source 10 of the reference voltage, the second output of which n to the zero potential bus, while the cathode of the tunnel diode 6 is connected to the source of the field-effect transistor 1 through the sixth resistor 11 and directly to the emitter of the pn-pn transistor 12, the collector of which is connected through the seventh resistor 13 to the first output bus 14 and sequentially connected to the eighth resistor 15 and the first coupling capacitor 16 - to the first output of the I7 generator of strobe pulses, the inverse output of which is connected through serially connected to the second coupling capacitor 18 and the ninth resistor 19 to the emitter of the pnp transistor 12 connected to the base through the tenth resistor 20 and through the eleventh resistor 21 to the second output bus 22, while the base of the npn transistor 12 is connected through the third coupling capacitor 23 to the input bus 24 Reset.

five

0

five

11, 8, 9, 15, 19, 13 and 21 can be equal in pairs, i.e. the circuit may be symmetrical.

The source 10 of the reference voltage sets the potential of the threshold device relative to the signal. The gating pulse generator 17 simultaneously generates the following identical gutter fields of gating pulses: positive at the direct, and negative at the inverse output.

Resistors 3 and 7 and field effect transistor 1 form an adjustable voltage divider.

The device works as follows.

The initial state of tunnel diode 6 is low voltage.

With uj, (fig. 2), the voltages at the drain and source of the field-effect transistor 1 are equal (the transistor is open), where 1 is the threshold voltage;

Uj. - voltage applied to

gate field-effect transistor 1.

When the voltage on the gate of the field-effect transistor 1 capacitance changes

0

shutter-drain

(WITH,.. )

(C, .and)

5-С

And gate source

.and / are charged along the circuits: the output impedance of the signal source, the resistors 3 and 7, respectively, and the internal resistance of the sources 4 and 10, which can be considered equal to zero. In this case, under the action of a predetermined current on the resistors 7 and 3, a voltage of the same shape and size is released, provided that the parameters of the capacitor charge circuits are the same.

0

If sa. 4- С

} -e

five

0

 The 3rd one needs to be equalized by connecting the appropriate capacitance to the gate-source and / or drain-drain electrodes. At time t, (Fig. 2), the gate pulse arrives, tunneling diode 6 does not switch.

As and c and f (fig. 2), the field effect transistor 1 closes and an increasing current UI begins to flow through the tunnel diode 6 under the action of the difference in voltage between the drain and the gate. Transient associated with charge C

mrs

and C

-and

no effect on size5

Well, ul, since the parameters of the transition process on the drain and source are identical.

The charge current of the pass-through capacitors (Cg5 ,,) of resistors 5 and 1 1 does not have a significant effect on the error of the response threshold when measuring a signal with a front duration of up to 0.1-0.5 NS, since the constant of resistors 5 and 11 is not more than 50 ps

At time tj, the value of 4I reaches 0.5, and when exposed to a gating pulse, starting at time t, the tunnel diode 6 switches to the high voltage state. To convert the tunnel diode 6 to a low-voltage state at time t on the input bus 24 Resetting the threshold device, a positive pulse is applied, opening the transistor 12. The collector-emitter circuit of transistor 12 shunts the tunnel diode 6. The current passes through the tunnel diode 6 is stopped and after it ends the action of the reset pulse, the transistor 12 is closed and the tunnel diode 6 goes into the initial low-voltage state.

Thus, the change in the threshold is made by changing the potential of the entire threshold device relative to the signal under investigation, which ensures that the operating modes of all elements of the device at the moment of operation are constant. Due to this, the measurement error of the amplitude parameters is determined only by the noise of the threshold device. This determines its precision.

Reducing the current-setting resistors 5 and 11 to tens of Ω increases the sensitivity and expands the device bandwidth, and the allowable input voltage of the device is limited only by the breakdown on the gate of the FET 1 (for the KP905 type transistor, the gate voltage is +30 V) . These features expand the dynamic range of the input voltages of the device while simultaneously extending the transmission band.

89034

Claims (1)

Invention Formula A gated threshold device containing a field effect transistor, the gate of which is connected to the input bus and the rod to the minus bus of the source 0 five 0 five power supply, through the first resistor, voltage source, strobe pulse generator, pn-transistor, the emitter of which is connected via a tunnel diode to the first output of the second resistor, third, fourth, fifth, sixth, seventh, eighth, nine Tin, tenth and eleventh resistors and output buses, characterized in that, in order to increase the accuracy and expand the dynamic range of the input voltages, three separation capacitors are introduced into it, the drain of the field-effect transistor connected through the third resistor to positive The power supply bus whose minus bus is connected to the first output of the voltage source, the second output of which is connected to the zero potential bus, and the anode and cathode of the tunnel diode are connected via the fourth and fifth resistors to the positive and negative buses, respectively.  The power source, with the emitter of the pnp transistor connected to the source of the field-effect transistor through the sixth resistor, the second output of the second resistor is connected to the field drain 5 transistors, and the collector of the pnp transistor is connected directly to the anode of the tunnel diode, via the seventh resistor to the first output bus and through the series-connected eighth resistor and the first a coupling capacitor to the forward output of a gating pulse generator, the inverse output of which is connected via serially connected second coupling capacitor and the ninth resistor to the emitter of the pnp transistor, which is connected to the base connected via the third separation capacitor to the bus Reset, 0 and through the tenth resistor and through eleventh resistor - to the second output bus. Input signal / i Bb / xoffnou sig / g Editor V. Petrov Tehred L, Serdyukov and Proofreader. Cherni 7823/58 Circulation 922 Subscription VNIIPI USSR State Committee for inventions and discoveries P3035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4