JPS6026327B2 - Slope signal generation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a slope signal generating circuit, and more particularly to a circuit capable of generating dominant slope signals of different polarities.

Horizontal sweep circuits for oscilloscopes, scanning circuits for televisions, function generators, and the like require oblique signals whose amplitude changes linearly with time.

It is well known to those skilled in the art that the generation of such a ramp signal typically involves the use of a current source and charge/discharge capacitor combination, a Miller integrator circuit, or a Putstrap circuit. However, such conventional circuits can only obtain single-ended signals, and cannot obtain push-pull signals with mutually opposite polarities.
For this purpose, a phase conversion amplifier (discrete phase amplifier) that converts a single-ended input into a push-pull output is generally used, but it is difficult to obtain an output with a desired amplitude and good balance. The present invention has been made in view of the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a novel circuit that can simultaneously or selectively generate slope signals of opposite polarity using a simple circuit configuration and a small number of circuit components. With the goal.

The technical problems, operations, and effects of the present invention can be easily understood from the following description with reference to the accompanying drawings.

FIGS. 1 and 2 show conventional slope signal generation circuits using a current source and a capacitor, respectively.
Generate polar and negative (falling) polarity ramp signals. a capacitor 10 connected at one end to a reference potential source (e.g. ground);
A current from a current source (current source 11 or current sink 11') is passed through 10'. This capacitor 10, 10'
The input terminal 13,
By applying a control signal from 13', capacitor 1
Controls charging and discharging of 0 and 10'. In this case capacitor 1
Voltage e across 0,10'. is expressed by the following equation. e.

=4 and a half = tHere, C is the capacitance of capacitors 10 and 10', 1 is the size of current sources 11 and 11', and t is capacitor 1
The charging time is 0.10'.

This voltage eo, which changes linearly with time, is transferred to a buffer amplifier,
For example emitter (or source) follower amplifier 14,1
It is used as an output signal from the output terminals 15, 15' via the terminal 4'.

In order to repeatedly generate this disturbing signal, the control circuits 12, 12' are activated by the control signal, and the capacitors 10, 10' are
All you have to do is charge and discharge repeatedly. As can be seen from the above explanation, at least two different current sources, a current source and a current sink, are required to generate cross-slant signals with opposite polarities, and also generate cross-slope signals with both positive and negative polarities at the same time. A separate capacitor is required for this purpose.

Furthermore, in order to obtain the desired balanced output signal, it is necessary to vary both current sources 11 and 11' equally and to make both capacitors 10 and 10' equal, which is difficult to achieve. Even if it is possible, it will be complicated and expensive. FIG. 3 is a principle diagram of a slope signal generation circuit according to the present invention.

A current from a common current line (current source) 11 is passed through a first capacitor 10a and a second capacitor 10b connected in series. Instead of connecting the lower end of the capacitor 10b to a reference potential source (for example, ground), the midpoint P between the capacitors 10a and 10b is connected to the inverting input terminal of a high input impedance differential amplifier, that is, a lid-type operational amplifier 16. Its non-inverting input terminal is connected to a reference potential source, for example ground. The other end of capacitor 10b is connected to the output end of amplifier 16. A buffer amplifier 14 is connected to a connection point Q between the current source 11 and the capacitor 10a. Output terminals 15a and 15b are provided at the output ends of both amplifiers 14 and 16. Also, capacitor 10
A control circuit 12 is connected in parallel with capacitors 10a and 10b, and a control signal applied to its input terminal 13 controls both capacitors 10a.
, 10b. Switch 1 of control circuit 12
When both 2a and 12b are on, the current 1 of the current source 11
flows into the output terminal of the amplifier 16 via the switches 12a and 12b, so the charges in the capacitors 10a and 10b are all discharged, and the potential at the output terminals 15a and 15b is substantially the same as the potential at the non-inverting input terminal of the amplifier 16. Equal ground potential.

Next, when the switches 12a and 12b are turned off by the control signal, all of the current 1 of the current source 11 is transferred to the capacitor 10a.
, 1ob, and the following voltages ew and eob are generated across the respective capacitors. Here C, oa, C, ob
t is the capacitance of the capacitors 10a and 10b, t is the time, and 1 is the current of the current source 11.

Note that in this case, the potential at point P is ground potential and remains substantially unchanged.

Therefore, the output signal eo at the output terminals 15a and 10b
As shown in FIG. 3, a and e are ramp signal voltages that linearly increase and decrease at a predetermined gradient with 0 volts as a reference, and as can be seen from the above equation, the gradient signal voltage is the gradient signal voltage of the current source 11. It is determined by the current 1 and the capacitance of the capacitors 10a and 10b. Therefore, if the capacitances of both capacitors 10a and 10b are selected equally, both signals eQ and e■ can be changed only by changing the current 1.
can be equally controlled. When the maximum voltage (amplitude) of these signals reaches a predetermined level below the operating voltage of the current source 11, a control signal is supplied to the input terminal 13 to close the switches 12a, 12b of the control circuit 12. Therefore, the burden on the capacitors 10a and 10b is rapidly discharged,
The output signal returns to the rest level (0 volts). In the illustrated example, the switches 12a and 12b are mechanical switches for the sake of simplicity, but they may also be electronic switches using relays or transistors (bipolar or unipolar). As is clear from the above description, according to the slope signal generation circuit of the present invention, a single current source, two capacitors,
By using a differential amplifier, two outputs that change with opposite polarities from a constant rest level can be obtained simultaneously, and the slope of the signal can be freely controlled by controlling the current 1 of the current source. Therefore, it can be suitably used in many applications requiring mutually inverse sacrificial slope signals. It should be noted that the switches 12a and 12b of the control circuit 12 do not need to be controlled at the same time, but can be controlled with a time delay or alternately turned on and off as necessary. In this case, one operation does not affect the other operation, that is, there is no interference, so the practical effect is even higher. Further, the current source 11 may be a current sink instead of a current source, but in that case, the output terminal 1
It should be noted that the polarities of the head oblique signal voltages eoa and eob obtained at 5a and 15b are opposite to those shown in the figure. Next, a novel usage example of the oblique signal generation circuit of the present invention will be explained based on FIG. The current source 11 is composed of a transistor 17, an emitter resistor 18, and a base voltage adjusting potentiometer 19. By adjusting the potentiometer 19, the output current 1 of the current source 11 can be changed continuously. A paraphase amplifier 20 is connected to the output sides of the buffer amplifier 14 and the differential amplifier 16. This amplifier 20 may be any conventional type of amplifier, but in the simplest example it may consist of a pair of transistors 21 with emitters coupled by a coupling resistor 23;
22, emitter resistors 24, 25 and collector load resistors 26, 27. amplifier 20
Note that as a general characteristic, the base input signal of the transistor 21 is phase-inverted and appears at the output terminal 15a'', but the base input signal of the transistor 22 is in phase (without phase inversion) and appears at the output terminal 15a''. I want to be Therefore, when the switch 12a is turned off while the control circuit 12b is turned on, the full pressure of the capacitor 10a is amplified by the paraphase amplifier 20 via the amplifier 14, and the output terminal 15 has a substantially balanced slope between the output terminals 15 and 15b'. Signal voltage is obtained. On the other hand, if the switch 12b is turned off while the switch 12a remains on, the charging pressure of the capacitor ob appears at the output terminals 15a' and 15b'. Here, for the reason mentioned above, even if the slope signal voltage appearing at the output terminals of the amplifiers 14 and 16 has opposite polarity, the output terminal 15a
Note that the signal polarities of ', 15b' are the same in both cases. Therefore, in the circuit of FIG. 4, the capacitors 10a and 10b have different capacitance values, for example, a ratio of 1:1.
By setting the ratio to 1:10 or 1:100, forehead oblique signal voltages with different magnifications are generated, which is suitable for use in horizontal deflection of an oscilloscope. Incidentally, if the resistance value of the emitter-coupled resistor 23 is made sufficiently smaller than that of the resistors 24 and 25, the balance of the output signal voltage can be improved. An oscilloscope with such a horizontal sweep circuit can perform many of the functions of an oscilloscope with two sweep circuits at substantially the same complexity and cost as one bridge circuit. The resistance value of the emitter resistor 18 of the current source 11 and the capacitor 1 may be adjusted as necessary.
It is clear that the capacitances of 0a and 10b can be switched and selected from a plurality of different values. Although the basic principle and usage examples of the present invention have been explained above, the present invention is not limited to these examples in any way, and various modifications and variations of the present invention are also included in the technical idea of the present invention. It is something.

[Brief explanation of the drawing]

1 and 2 are conventional tilt signal generation circuits; FIG. 3 is a circuit diagram showing the basic principle of the tilt signal generation circuit of the present invention; and Figure 4 is a circuit diagram showing an example of the application of the forehead tilt signal generation circuit of the present invention. It is a circuit diagram. In the figure, 10a and 10b are first and second capacitors, respectively;
11 is a current source, 12 is a control circuit, 16 is a differential amplifier, 1
4 indicates a buffer amplifier. FIG. l FIG. 2 FIG. 3 FIG. Mu

Claims (1)

[Claims] 1. A current source, first and second capacitors connected in series to the current source, an inverting input end connected to a connection point between the two capacitors, and the other end of the second capacitor being output. connect to the end,
A differential amplifier having a non-inverting input terminal connected to a desired reference potential source, and a control circuit connected in parallel to both of the capacitors,
A slope signal generation circuit characterized in that an output signal is obtained from an output end of the differential amplifier and a connection point between the current source and the first capacitor. 2. A patent claim characterized in that the control circuit is provided with first and second switches connected in parallel to the first and second capacitors, respectively, and selectively controls on/off of the switches at the same time or at different times. The slope signal generation circuit according to item 1.