CN214626941U - Linear oblique transformation circuit - Google Patents
Linear oblique transformation circuit Download PDFInfo
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- CN214626941U CN214626941U CN202120347348.3U CN202120347348U CN214626941U CN 214626941 U CN214626941 U CN 214626941U CN 202120347348 U CN202120347348 U CN 202120347348U CN 214626941 U CN214626941 U CN 214626941U
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- operational amplifier
- transconductance operational
- ramp
- phase input
- voltage
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Abstract
The utility model relates to a linear ramp circuit, including operational amplifier, operational amplifier is transconductance operational amplifier, and transconductance operational amplifier's negative phase input passes through soft switch SW that opensINAnd a variable bias current source IINConnected with the positive phase input end of the transconductance operational amplifier and the voltage VBConnected, the output end of the transconductance operational amplifier is connected with a node VOUTA capacitor C is connected between the negative phase input end and the output end of the transconductance operational amplifier in a bridging manner1A soft switch SW is connected between the negative phase input end and the output end of the transconductance operational amplifier in a bridging way0. The power port of the transconductance operational amplifier is connected with a bias current source IB which is connected in parallel0、IB1To IBNWherein a bias current source IB1To IBNIn the loop of the switch is correspondingly connected with a soft switch SW in seriesITo SWN. The utility model discloses can realize the accurate control to the ramp speed, the ramp voltage value that fall to the slope of oblique circuit, can not produce burr voltage, improve the work efficiency of oblique circuit, enlarge the working range of oblique circuit.
Description
Technical Field
The utility model relates to a linear oblique transformer circuit belongs to intelligent electron technical field.
Background
The ramp circuit is a circuit in which an output signal gradually rises or falls at a set rate when an input signal abruptly changes.
The ramp circuit is widely used as a reference signal generator in electronic systems of display devices, for example: the display device displays variable brightness through a large number of pixels, wherein the input end of the ramp circuit may receive a pulse input signal, the pulse input signal switches the switch, when the switch is switched to a state 1, the output signal of the ramp circuit starts to gradually rise, the rising speed of the output signal depends on the charging speed of the capacitor, and when the switch is switched to a state 2, the output signal of the ramp circuit starts to gradually fall, the falling speed of the output signal depends on the discharging speed of the capacitor.
The conventional ramp circuit has the following problems: (1) the ramp-up speed and the ramp-down speed of the output signal cannot be controlled, and a large burr voltage is generated at the moment of switching on the switch, so that the safety of the system is influenced; (2) the output signal is difficult to ramp down to a set accurate voltage value; if the speed can be reached, the work efficiency of the system is limited due to the over-slow ramp-down speed; (3) the control requirement on the switch time sequence is accurate, and the difficulty is high; (4) it must work in a linear working area.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to overcome the problem that exists among the prior art, provide a linear oblique circuit, can realize the accurate control to oblique ramp speed, the voltage value that falls to one side of oblique circuit, improve oblique circuit's work efficiency, enlarge oblique circuit's working range.
The utility model discloses a linear ramp circuit, including operational amplifier, operational amplifier is transconductance operational amplifier, transconductance operational amplifier's negative phase input is through soft open switch SWINAnd a variable bias current source IINAre connected with each otherPositive phase input end of transconductance operational amplifier and voltage VBThe output end of the transconductance operational amplifier is connected with a node VOUTA capacitor C is connected between the negative phase input end and the output end of the transconductance operational amplifier in a bridging manner1A soft switch SW is connected between the negative phase input end and the output end of the transconductance operational amplifier in a bridging way0。
Furthermore, the power supply port of the transconductance operational amplifier is connected with a bias current source IB which is connected in parallel0、IB1To IBNN is an integer greater than 1, wherein the bias current source IB1To IBNIn the loop of the switch is correspondingly connected with a soft switch SW in seriesITo SWN。
The utility model has the advantages that: 1. in the process of the linear ramp circuit ramp-down, the bias current I of the negative phase input end of the transconductance operational amplifierINVariable capacitor C connected across the output terminal and negative input terminal of the transconductance operational amplifier1And soft switching switch SW0The transconductance operational amplifier can exit from the linear working region, and at the moment, the transconductance operational amplifier works in a sharp-turn state, and the output signal can be rapidly ramped down but the speed is controllable.
2. The bias current source of the input stage differential pair of the transconductance operational amplifier is a variable current source, the current value of which is reduced in the ramp-down process compared with the current value in the ramp-up process, and the soft switching switch SW0In cooperation, the voltage at the negative input terminal of the transconductance operational amplifier is boosted to a high potential far greater than the voltage V at the positive input terminal of the transconductance operational amplifierB. The transconductance operational amplifier of the linear ramp circuit works in a nonlinear working area in the ramp-down process, and the ramp curve is a linear curve, because the condition that the voltage of the negative phase input end of the transconductance operational amplifier is equal to the voltage of the positive phase input end, the maximum value of the output voltage of the transconductance operational amplifier is 200 millivolts lower than that of a positive power supply, and the minimum value of the output voltage of the transconductance operational amplifier is 200 millivolts higher than that of the negative power supply is adopted by the transconductance operational amplifier in the linear working area. The output voltage of the linear ramp circuit can be obtained when the linear ramp-down process is finishedIt is easy to reach the accurate value VBAnd because the linear ramp-down speed is controllable, no glitch voltage is generated. The current source connected to the positive phase input end of the transconductance operational amplifier can easily realize linear ramp-up of the output signal of the linear ramp circuit; by employing suitable timing control, a controllable and suitable dead time can be generated.
3. In the linear ramp-down process, the positive phase input voltage of the transconductance operational amplifier maintains VBAnd when the voltage difference between the negative phase input end voltage and the positive phase input end voltage of the transconductance operational amplifier is unchanged, the transconductance operational amplifier works in a nonlinear working area, and the output end of the transconductance operational amplifier is rapidly ramped down.
4. In the linear ramp-down process, the positive phase input voltage of the transconductance operational amplifier maintains VBAnd when the voltage difference between the negative phase input end voltage and the positive phase input end voltage of the transconductance operational amplifier is constant, the transconductance operational amplifier works in a nonlinear working area, and the output end of the transconductance operational amplifier realizes slow ramp-down.
5. Bias current source IB1To IBNIn the loop of the switch is correspondingly connected with a soft switch SW in seriesITo SWNI.e. comprising N +1 current sources, wherein a switch is present in the current path of the N current sources, the switch SW being opened softly during the ramp-upITo SWNThe switches are all closed; soft switch off SW during ramp downITo SWNIs completely or partially disconnected, so that the bias current value of the input stage differential pair of the transconductance operational amplifier is reduced in the ramp-down process compared with the current value in the ramp-up process, and the soft switch SW0In cooperation, the voltage at the negative input terminal of the transconductance operational amplifier is boosted to a high potential far greater than the voltage V at the positive input terminal of the transconductance operational amplifierBAnd the transconductance operational amplifier is led out of the linear working area. By closing or opening different switches in the ramp-down process, the bias current of the input stage differential pair of the transconductance operational amplifier can be changed into different current values, so that ramp-down curves with different speeds are obtained.
Drawings
Fig. 1 is a schematic diagram of a linear ramp circuit according to the present invention;
FIG. 2 is a waveform diagram of the output of the linear ramp circuit of FIG. 1;
fig. 3 is a circuit node waveform diagram of the linear ramp circuit of the present invention during rapid ramp-down;
FIG. 4 is a waveform diagram of a circuit node when the linear ramp circuit of the present invention is slowly ramped down;
fig. 5 is a graph illustrating the variable input bias current and the corresponding ramp down rate of the transconductance operational amplifier.
Detailed Description
The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic drawings and illustrate the basic structure of the present invention only in a schematic manner, and thus show only the components related to the present invention.
As shown in FIG. 1, the linear ramp circuit of the present invention comprises an operational amplifier, wherein the operational amplifier is a transconductance operational amplifier, and the negative phase input terminal of the transconductance operational amplifier is connected to the switch SW through a soft switchINAnd a variable bias current source IINConnected with the positive phase input end of the transconductance operational amplifier and the voltage VBConnected, the output end of the transconductance operational amplifier is connected with a node VOUTA capacitor C is connected between the negative phase input end and the output end of the transconductance operational amplifier in a bridging manner1A soft switch SW is connected between the negative phase input end and the output end of the transconductance operational amplifier in a bridging way0。
As shown in FIG. 2, the bias current source of the input stage differential pair of the transconductance operational amplifier is a variable current source, which decreases during the ramp-down process compared to the ramp-up process, and the soft switch SW0In cooperation, the voltage at the negative input terminal of the transconductance operational amplifier is boosted to a high potential far greater than the voltage V at the positive input terminal of the transconductance operational amplifierB. The transconductance operational amplifier works in a linear working area under the condition that the voltage of the negative phase input end of the transconductance operational amplifier is equal to the voltage of the positive phase input end, the maximum value of the output voltage of the transconductance operational amplifier is 200 millivolts lower than that of the positive power supply, and the output voltage of the transconductance operational amplifier is the mostThe small value is 200 millivolts higher than the negative power supply voltage, so the transconductance operational amplifier of the linear ramp circuit works in a nonlinear working area in the ramp-down process, and the ramp curve is a linear curve. The output voltage of the linear ramp circuit can easily reach the accurate value V when the linear ramp-down process is finishedBAnd because the linear ramp-down speed is controllable, no glitch voltage is generated. The current source connected to the positive phase input end of the transconductance operational amplifier can easily realize linear ramp-up of the output signal of the linear ramp circuit; by employing suitable timing control, a controllable and suitable dead time can be generated.
As shown in FIG. 3, during the linear ramp down, the positive input voltage of the transconductance operational amplifier maintains VBAnd when the voltage difference between the negative phase input end voltage and the positive phase input end voltage of the transconductance operational amplifier is unchanged, the transconductance operational amplifier works in a nonlinear working area, and the output end of the transconductance operational amplifier is rapidly ramped down.
As shown in FIG. 4, during the linear ramp down, the voltage at the positive input terminal of the transconductance operational amplifier maintains VBAnd when the voltage difference between the negative phase input end voltage and the positive phase input end voltage of the transconductance operational amplifier is constant, the transconductance operational amplifier works in a nonlinear working area, and the output end of the transconductance operational amplifier realizes slow ramp-down.
As shown in fig. 5, the power port of the transconductance operational amplifier is connected with a bias current source IB connected in parallel with each other0、IB1To IBNN is an integer greater than 1, wherein the bias current source IB1To IBNIn the loop of the switch is correspondingly connected with a soft switch SW in seriesITo SWNI.e. there are switches in the current paths of the N current sources. Soft-open switch SW during ramp-upITo SWNThe switches are all closed; soft switch off SW during ramp downITo SWNIs completely or partially disconnected, so that the bias current value of the input stage differential pair of the transconductance operational amplifier is reduced in the ramp-down process compared with the current value in the ramp-up process, and the soft switch SW0In cooperation, the negative input terminal voltage of the transconductance operational amplifier is boosted to a high potential far greater than the transconductancePositive phase input terminal voltage V of operational amplifierBAnd the transconductance operational amplifier is led out of the linear working area. By closing or opening different switches in the ramp-down process, the bias current of the input stage differential pair of the transconductance operational amplifier can be changed into different current values, so that ramp-down curves with different speeds are obtained.
In light of the foregoing, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.
Claims (2)
1. A linear ramp circuit comprising an operational amplifier, characterized in that: the operational amplifier is a transconductance operational amplifier, and the negative phase input end of the transconductance operational amplifier passes through a soft-open switch SWINAnd a variable bias current source IINThe positive phase input end of the transconductance operational amplifier is connected with the voltage VBThe output end of the transconductance operational amplifier is connected with a node VOUTA capacitor C is connected between the negative phase input end and the output end of the transconductance operational amplifier in a bridging manner1A soft switch SW is connected between the negative phase input end and the output end of the transconductance operational amplifier in a bridging way0。
2. The linear ramp circuit of claim 1, wherein: the power port of the transconductance operational amplifier is connected with a bias current source IB which is connected in parallel0、IB1To IBNN is an integer greater than 1, wherein the bias current source IB1To IBNIn the loop of the switch is correspondingly connected with a soft switch SW in seriesITo SWN。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120347348.3U CN214626941U (en) | 2021-02-07 | 2021-02-07 | Linear oblique transformation circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120347348.3U CN214626941U (en) | 2021-02-07 | 2021-02-07 | Linear oblique transformation circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN214626941U true CN214626941U (en) | 2021-11-05 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202120347348.3U Active CN214626941U (en) | 2021-02-07 | 2021-02-07 | Linear oblique transformation circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN214626941U (en) |
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2021
- 2021-02-07 CN CN202120347348.3U patent/CN214626941U/en active Active
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