TWI490676B - Current calibration circuit and current calibration method for adjusting current input generated from current source, and ramp generator - Google Patents

Description

Current correction circuit and current correction method for adjusting current input generated by current source Method, and ramp generator

The present invention relates to current correction, and more particularly to a current correction circuit for adjusting the current input generated by a current source, and its associated current correction method and ramp generator.

The ramp linearity of the ramp generator and the accuracy of the ramp slope can be improved by providing a stable current source. Since the bandgap reference voltage provides a stable voltage source, the bandgap reference voltage can be converted to the required current through the resistive element. However, the resistance value of the resistive element still slightly The change causes the current generated by the bandgap reference voltage to also vary, which in turn affects the performance of the ramp generator.

Therefore, there is a need for a design mechanism that allows a current source to stably provide a current input to solve the above problems.

In view of the above, it is an object of the present invention to provide a current correcting circuit for adjusting a current input generated by a current source, and a related current correcting method and a ramp generator to solve the above problems.

In accordance with an embodiment of the invention, a current correction circuit for adjusting a current input generated by a current source is disclosed. The current correction circuit includes a processing function block and an adjustment function block. The processing function block is coupled to the current source for receiving a predetermined reference voltage input and the current input, and generating a processing result according to the predetermined reference voltage input and the current input. The adjustment function block is coupled to the processing function block and the current source for generating an adjustment signal to the current source to adjust the current input according to the processing result, so that the current input is different from the predetermined reference voltage. There is a predetermined ratio between the sizes of the inputs.

According to another embodiment of the present invention, a current correction method for adjusting a current input generated by a current source is disclosed. The current calibration method includes the steps of: generating a processing result according to a predetermined reference voltage input and the current input; and generating an adjustment signal to the current source according to the processing result to adjust the current input to make the current input There is a predetermined ratio between the magnitude of the predetermined reference voltage input.

According to another embodiment of the present invention, a ramp generator is further disclosed. The ramp generator includes a current source, a current correction circuit, and a ramp generation circuit. The current source is used to generate a current input. The current correction circuit is configured to adjust the current input generated by the current source. The ramp generating circuit is coupled to the current source for generating a ramp signal according to the current input adjusted by the current correcting circuit. The current correction circuit includes a processing function block and an adjustment function block. The processing function block is coupled to the current source for receiving a predetermined reference voltage input and the current input, and generating a processing result according to the predetermined reference voltage input and the current input. The adjustment function block is coupled to the processing function block and the current source for generating an adjustment signal to the current source to adjust the current input according to the processing result, so that the current input is different from the predetermined reference voltage. There is a predetermined ratio between the sizes of the inputs.

The current correction circuit disclosed in the present invention can be input according to a predetermined reference voltage (for example, The bandgap reference voltage is used to adjust the current input, thereby reducing/reducing the effect of variations in the resistive component on the current input, thereby improving the performance of the ramp generator (eg, ramp linearity or ramp slope).

100, 200, 400‧‧‧ current correction circuit

110, 210, 410‧‧‧ processing function blocks

120, 220‧‧‧Adjustment function block

212, 412‧‧‧Control unit

214, 414‧‧‧ core unit

216, 226‧ ‧ amplifier

600‧‧‧ ramp generator

602‧‧‧ ramp generation circuit

CR‧‧‧current source

SW1, SW2, SW3, SW4, SW5, SW6‧‧‧ switch

C, C1, C2, C3‧‧‧ capacitor

NS, N1, N2‧‧‧ endpoints

V_R‧‧‧ reference voltage terminal

P_1, P_2, P_A, P_B‧‧‧ input埠

P_OUT, P_C‧‧‧ output埠

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a functional block diagram of one embodiment of a current correction circuit of the present invention.

Figure 2 is a schematic diagram of one embodiment of a current correction circuit for adjusting a current input generated by a current source.

Figure 3 is a timing diagram of an example of a practical example of a plurality of switch control signals for controlling a plurality of switchers shown in Figure 2.

Figure 4 is a schematic illustration of another embodiment of a current correction circuit for adjusting a current input generated by a current source.

Figure 5 is a timing diagram of an example of a practical example of a plurality of switch control signals for controlling a plurality of switchers shown in Figure 4.

Figure 6 is a functional block diagram of an embodiment of a ramp generator of the present invention.

Please refer to FIG. 1. FIG. 1 is a functional block diagram of an embodiment of a current correction circuit according to the present invention. The current calibration circuit 100 is used to adjust a current input I_IN generated by a current source CR, and includes a processing block 110 and an adjustment block 120. As shown in FIG. 1 , the processing function block 110 is coupled to the current source CR for receiving a predetermined reference voltage input V_IN and a current input I_IN, and generates a processing result PR according to the predetermined reference voltage input V_IN and the current input I_IN. The adjustment function block 120 is coupled to the processing function block 110 and the current source CR for generating an adjustment signal S_A to the current source CR according to the processing result PR to adjust the current input I_IN to input the current input I_IN. There is a predetermined ratio between the magnitude of the predetermined reference voltage input V_IN. In a practical example, a predetermined reference voltage input V_IN can be a bandgap reference voltage.

For example (but the invention is not limited thereto), the current input I_IN to be adjusted can be converted into a voltage signal, and the predetermined reference voltage input V_IN is compared with the voltage signal to generate a processing result PR (for example, two Next, the adjustment function block 120 generates an adjustment signal S_A (for example, a voltage signal or a current signal) to the current source CR according to the processing result PR to adjust the current input I_IN. In a practical example, the voltage value of the voltage signal corresponding to the current input I_IN may be finally adjusted to be equal to the voltage value of the predetermined reference voltage input V_IN. In another implementation example, the current input I_IN can be adjusted by transmitting an adjustment signal S_A (eg, a voltage signal or a current signal) to a current mirror branch of the current source CR. Please note that the above is for illustrative purposes only and is not intended to be a limitation of the present invention, that is, as long as it is used for a predetermined reference voltage input (for example, a bandgap reference voltage) and one of the current inputs to be adjusted. Processing is performed to generate a processing result, and according to the processing result, an adjustment signal is generated to the current source to adjust the current input, so that the adjusted current input is maintained at a stable current value (for example, the magnitude of the current input is A current correction mechanism having a predetermined ratio between the predetermined reference voltage inputs is in accordance with the inventive spirit of the present invention. Further explanation is detailed below.

Please refer to FIG. 2, which is a schematic diagram of an embodiment of a current correction circuit for adjusting a current input I_IN generated by a current source CR. The current correction circuit 200 includes a processing function block 210 and an adjustment function block 220. The processing function block 110 shown in FIG. 1 can be implemented by using the processing function block 210, and the adjustment function block 120 shown in FIG. 1 can be The adjustment function block 220 is used to make it. The processing function block 210 includes a control unit 212, a core unit 214, a first capacitor C1, a first switch SW1, and a second switch SW2. The first capacitor C1 is coupled between the core unit 214 and a first specific end point N1, wherein the core unit 214 is for the current input I_IN. And processing the predetermined reference voltage V_IN input to store an output result R_O to the first capacitor C1, and then adjusting the output result R_O to cause the first capacitor C1 to store the processing result PR. As shown in FIG. 2, the core unit 214 includes an amplifier 216, a second capacitor C2, a third capacitor C3, a third switch SW3, a fourth switch SW4, and a fifth switch SW5. A sixth switch SW6. As shown in FIG. 2, the amplifier 216 has a first input 埠P_1, a second input 埠P_2, and an output 埠P_OUT, wherein the second input 埠P_2 is coupled to a reference voltage terminal V_R (for example, having a certain voltage ( Constant voltage) or the voltage terminal of a ground voltage). The second capacitor C2 is coupled between the first input 埠P_1 and the output 埠P_OUT, and the third capacitor C2 is coupled between the first input 埠P_1 and a second specific end point N2. The control unit 212 is configured to generate a plurality of switch control signals S_C1~S_C6, wherein the plurality of switch control signals S_C1~S_C6 are respectively used to control a plurality of switch switches SW1~SW6 to be closed/turned on (open/turned on) And the first switch SW1 is configured to selectively couple the first specific end point N1 to the reference voltage terminal V_R according to the first switch control signal S_C1. The second switch SW2 is configured to selectively couple the first specific end point N1 to the adjustment function block 220 according to the second switch control signal S_C2; the third switch SW3 is selected according to the third switch control signal S_C3 The current source CR is coupled to the first input port _1P_1; the fourth switch switch SW4 selectively couples the predetermined reference voltage input V_IN to the second specific end point N2 according to the fourth switch control signal S_C4; The switch SW5 selectively couples the first input 埠P_1 to the output 埠P_OUT according to the fifth switch control signal S_C5; and the sixth switch SW6 selectively selects the second specific according to the sixth switch control signal S_C6 Node N2 is coupled to a reference voltage terminal V_R.

In this embodiment, the adjustment function block 220 includes an amplifier 226 and a capacitor C. The amplifier 226 has a plurality of inputs 埠P_A and P_B, and an output 埠P_C, wherein the input 埠P_A is used to receive the processing result PR, the output 埠P_C is used to output the adjustment signal S_A, and the input 埠P_B is coupled to the reference voltage terminal V_R. . In addition, the capacitor C is coupled to the input port _P_A Between the output 埠P_C and the output. Please refer to FIG. 2 together with FIG. 3, wherein FIG. 3 is a signal timing sequence for controlling one of the plurality of switch control signals S_C1 to S_C6 of the plurality of switch switches SW1 to SW6 shown in FIG. Figure. In this implementation example, when a switch control signal is at a first voltage level (eg, a high voltage level), the switch controlled by the switch control signal is turned on/on, and when the switch is controlled When the signal is at a second voltage level (for example, a low voltage level), the switch controlled by the switch control signal is turned on/off. In a design change, a plurality of switch switches SW1~SW6 can also be set to be closed/conducted when a plurality of switch control signals S_C1~S_C6 are at a low voltage level.

For example, (but the invention is not limited thereto), when the current input I_IN is converted into a voltage signal, when the first switch SW1, the third switch SW3, and the fourth switch SW4 are both closed (closed), while the second changeover switch SW2, the fifth changeover switch SW5, and the sixth changeover switch SW6 are both in an open state (ie, after time point T1), the core unit 214 utilizes a current input I_IN pair The second capacitor C2 is charged to generate a voltage signal at the output 埠P_OUT, and a circuit composed of the second capacitor C2, the third capacitor C3 and the amplifier 216 is used to generate another voltage signal corresponding to the predetermined reference voltage input V_IN at the output 埠P_OUT. That is, the voltage value of the output 埠P_OUT is contributed by the current input I_IN and the predetermined reference voltage input V_IN. In a practical example, when the reference voltage terminal V_R is a ground, the voltage value of the other voltage signal is -V_IN×(C3/C2), and therefore, is stored in the first capacitor. The output result R_O of C1 (that is, the voltage value of the output 埠P_OUT) can be regarded as a voltage difference between the voltage signal and the predetermined reference voltage input V_IN.

When the third switch SW3 and the fourth switch SW4 are both switched from the on state to the closed state, and the first switch S1 is still in the closed state (that is, after the time point T2), the output is stored in the first capacitor C1. As a result, R_O tends to be stable. When the first switch SW1, the third switch SW3, and the fourth switch SW4 are both in an open state (ie, time point T3) Thereafter, since the capacitor has a characteristic of maintaining a fixed voltage drop, the core unit 214 can change the potential of the first specific end point N1 by adjusting the voltage value of the output 埠P_OUT (ie, the output result R_O) ( That is, the result is PR). More specifically, after the time point T4, the second changeover switch SW2, the fifth changeover switch SW5, and the sixth changeover switch SW6 are all switched from the on state to the closed state, and therefore, the voltage value of the output 埠P_OUT is adjusted as a reference. The voltage of the voltage terminal V_R (eg, a ground voltage), and the first capacitor C1 may output the potential of the first specific terminal N1 (ie, the processing result PR) to the adjustment function block 220 for subsequent adjustment operations. For example, in the case where the reference voltage terminal V_R is a ground terminal, when the first specific terminal point N1 is not coupled to the reference voltage terminal V_R (for example, at the time point T4), the core unit 214 can output a ground voltage. As the output result R_O, the first capacitor C1 stores the processing result PR. Therefore, the core unit 214 can adjust the voltage value of the output 埠P_OUT from the voltage difference (for example, -1 volt) to the ground voltage. (for example, 0 volts), such that the potential of the first specific terminal N1 also has an adjustment range of the voltage difference (for example, 1 volt), therefore, the adjustment function block 220 can input the I_IN and the predetermined reference voltage according to the received current. The information of the difference between V_IN (that is, the voltage difference described above) is input to generate the adjustment signal S_A to adjust the current input I_IN.

As described above, after time point T4, the adjustment function block 220 can receive the potential of the first specific end point N1 (i.e., the processing result PR), in other words, the input 埠P_A receives the potential of the first specific end point N1. In this embodiment, the adjustment function block 220 can be regarded as an integrator circuit. Therefore, the potential of the output 埠P_C (ie, the adjustment signal S_A) can follow the potential of the input 埠P_A (ie, the processing result PR) ) to adjust to achieve the purpose of stabilizing the current input I_IN. In addition, the second changeover switch SW2 can be switched from the closed state to the open state (as indicated by the time point T6) after the fifth changeover switch SW5 is switched from the closed state to the open state (as indicated by the time point T5). In an implementation example, the current correction circuit 200 may repeatedly perform the operation of adjusting the current input I_IN until the processing result PR received by the adjustment function block 220 indicates that the current input I_IN has not been adjusted (eg, the adjusted first specific endpoint) The potential of N1 is still the grounding current Press). In other words, the predetermined ratio of the magnitude of the current input I_IN to the magnitude of the predetermined reference voltage input V_IN. It is to be noted that the above description is for illustrative purposes only and is not intended to be a limitation of the invention. In a design change, it is also feasible to couple the reference voltage terminal V_R to a constant voltage of a non-ground voltage. In another design change, the predetermined reference voltage input V_IN can also be converted into a current signal for the core unit 214 to process the current signal and the current input I_IN.

It can be seen from the above that in the preferred embodiment, the relationship between the plurality of switch control signals S_C1~S_C6 can be simply summarized as follows: the fourth switch control signal S_C4 and the sixth switch control signal S_C6 are non-overlapping signals, and the third switch The control signal S_C3 and the fifth switch control signal S_C5 are non-overlapping signals, and the first switch control signal S_C1, the third switch control signal S_C3, and the fourth switch control signal S_C4 are at least partially overlapped, and the second switch control signal S_C2, The five-switch control signal S_C5 and the sixth switch control signal S_C6 are at least partially overlapped. In addition, the first changeover switch SW1 is switched from the closed state to the open state after the third changeover switch SW3 and the fourth changeover switch SW4 are switched from the closed state to the open state. The second changeover switch SW2 is switched from the closed state to the open state after the fifth changeover switch SW5 is switched from the closed state to the open state.

Please note that the processing function block 110 shown in FIG. 1 is implemented by using the circuit architecture of the processing function block 210 shown in FIG. 2 as an example. In other words, any predetermined reference voltage input V_IN and current input I_IN can be performed. The circuit architecture for processing and generating the processing result PR for the information of the predetermined reference voltage input V_IN and the current input I_IN can be used by the processing function block 110 shown in FIG. 1; similarly, as shown in FIG. The circuit structure of the adjustment function block 220 is implemented as an adjustment function block 120 shown in FIG. 1 for illustrative purposes only. In other words, any circuit structure that can adjust the current input I_IN according to the processing result PR can be shown in FIG. The adjustment function block 120 is adopted. These design variations are within the scope of the invention.

Moreover, since the circuit structure of the processing function block 210 and the adjustment function block 220 shown in FIG. 2 is only one possible implementation manner of the current correction circuit of the present invention, the number of the switching switch and the switch control signal described above is only For the purpose of illustration, it is not intended to be a limitation of the present invention. As long as the processing result PR of generating a predetermined information of the predetermined reference voltage input V_IN and the current input I_IN can be achieved, the number of the switch and the switch control signal is not Limited to the number shown in Figure 2. Please refer to FIG. 4, which is a schematic diagram of another embodiment of a current correction circuit for adjusting a current input I_IN generated by a current source CR. The architecture of the current correction circuit 400 is based on the first The diagram and the architecture of the current correction circuit shown in FIG. As can be seen from FIG. 4, the current correction circuit 400 includes an adjustment function block 120 shown in FIG. 1 and a processing function block 410. In addition, the processing function block 410 includes a control unit 412, a core unit 414, and a first capacitor C1, a first switch SW1, and a second switch SW2 shown in FIG. Similarly, the core unit 414 processes the current input I_IN and the predetermined reference voltage V_IN input to store an output result R_O to the first capacitor C1, and then adjusts the output result R_O to cause the first capacitor C1 to store the processing result PR. The control unit 412 is configured to generate a plurality of switch control signals including at least a first switch control signal S_C1 and a second switch control signal S_C2, wherein the first switch control signal S_C1 and the second switch control signal S_C2 are respectively used Controlling the closing/turning on and off of the first switching switch SW1 and the second switching switch SW2, more specifically, the first switching switch SW1 is configured to selectively select the first specific according to the first switching control signal S_C1 The terminal N1 is coupled to a reference voltage terminal V_R (for example, a voltage terminal having a certain voltage or a ground voltage), and the second switch SW1 is configured to selectively select the first specific component according to the second switch control signal S_C2 End point N1 is coupled to adjustment function block 120.

Please refer to Figure 4 together with Figure 5, where Figure 5 is the signal timing for the implementation of one of the plurality of switch control signals S_C1~S_C2 used to control the plurality of switches SW1~SW2 shown in Figure 4. Figure. For example (but the invention is not limited thereto), in the case where the current input I_IN is converted into a voltage signal, when the first switching switch S1 is in the closed state and the second switching When the switch SW2 is in the on state (that is, after the time point T1), the core unit 414 can store the voltage difference between the voltage signal and the predetermined reference voltage input V_IN to the first capacitor C1, that is, the end point. The potential of NS (ie, the output result R_O) will approach the voltage difference; when the first switch SW1 is in the on state (ie, after time point T2), the core unit 214 can adjust the endpoint NS. a potential (ie, an output result R_O) to change a potential of the first specific end point N1 (ie, a processing result PR); and when the first changeover switch SW1 is in an on state and the second changeover switch SW2 is in a closed state ( That is, after the time point T3), after the core unit 214 adjusts the potential of the terminal NS (that is, the output result R_O), the first capacitor C1 can set the potential of the first specific end point N1 (ie, the processing result) PR) is output to adjustment function block 120 for subsequent adjustment operations. Note that it is also feasible to perform the operation of adjusting the potential of the terminal NS (i.e., outputting the result R_O) after the time point T3.

As described above, the operation of the switch of the current correcting circuit 400 and the storage/transfer of the signal can be simply summarized as follows: when the first specific end point N1 is coupled to the reference voltage terminal V_R and the first specific end point N1 is not coupled to the adjustment When the function block 120 is used, the first capacitor C1 stores the output result R_O; and when the first specific end point N1 is not coupled to the reference voltage terminal V_R, the first capacitor C1 stores the processing result PR and is at the first specific end point. When N1 is coupled to the adjustment function block 120, the first capacitor C1 outputs the processing result PR to the adjustment function block 120. In addition, in the preferred embodiment, the first switch control signal S_C1 and the second switch control signal S_C2 are non-overlapping signals. In addition, in a case where the reference voltage terminal V_R is a ground terminal, when the first specific terminal end N1 is not coupled to the reference voltage terminal V_R, the core unit 414 can output a ground voltage as the output result R_O to make the first capacitor. C1 stores the processing result PR. Since the skilled artisan can easily understand the operation details of the current correcting circuit 400 after reading the descriptions of FIGS. 1 to 3, further description will not be repeated here.

Please refer to FIG. 6. FIG. 6 is a ramp generator of the present invention. A functional block diagram of one embodiment. The ramp generator 600 includes, but is not limited to, a current source CR, the aforementioned current correction circuit 100/200/400, and a ramp generator circuit 602. The current source CR is used to generate a current input I_IN, and the current correction circuit 100/200/400 is used to adjust the current input I_IN generated by the current source CR. The ramp generating circuit 602 is coupled to the current source CR for generating a ramp signal S_R according to the current input I_IN adjusted by the current correcting circuit 100/200/400. Since the skilled artisan can easily understand the operation details of the ramp generator 600 after reading the descriptions of FIGS. 1 to 5, further description will not be repeated here.

In summary, the current correction circuit disclosed in the present invention can adjust the current input according to a predetermined reference voltage input (for example, a bandgap reference voltage), thereby reducing/reducing the influence of the variation of the resistive component on the current input, thereby improving the slope. The performance of the wave generator (for example, ramp linearity or ramp slope).

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

100‧‧‧ Current correction circuit

110‧‧‧Processing function block

120‧‧‧Adjustment function block

CR‧‧‧current source

Claims (13)

A current correction circuit for adjusting a current input generated by a current source, comprising: a processing function block coupled to the current source for receiving a predetermined reference voltage input and the current input generated by the current source And generating a processing result according to the predetermined reference voltage input and the current input generated by the current source; and an adjustment function block coupled to the processing function block and the current source for generating according to the processing result An adjustment signal is applied to the current source to adjust the current input generated by the current source such that a magnitude of the current input generated by the current source has a predetermined ratio between the magnitude of the predetermined reference voltage input. The current correction circuit of claim 1, wherein the processing function block comprises: a control unit for generating a plurality of switch control signals, wherein the plurality of switch control signals comprise at least a first switch control signal and a second switch control signal; a core unit; a first capacitor coupled between the core unit and a first specific terminal, wherein the core unit processes the current input and the predetermined reference voltage input for storage And outputting the result to the first capacitor, and adjusting the output result to cause the first capacitor to store the processing result; a first switching switch for selectively selecting the first specific end according to the first switch control signal The point is coupled to a reference voltage terminal; and a second switch is configured to selectively couple the first specific terminal to the adjustment function block according to the second switch control signal. The current correction circuit of claim 2, wherein the first capacitor is coupled to the reference voltage terminal and the first specific terminal is not coupled to the adjustment function block, the first capacitor The output result is stored; and when the first specific endpoint is not coupled to the reference voltage terminal The first capacitor stores the processing result, and when the first specific end is coupled to the adjustment function block, the first capacitor outputs the processing result to the adjustment function block. The current correction circuit of claim 2, wherein the first switch control signal and the second switch control signal are non-overlapping signals. The current correction circuit of claim 2, wherein the reference voltage terminal is a ground terminal, and when the first specific terminal is not coupled to the reference voltage terminal, the core unit outputs a ground voltage As the output result, the first capacitor stores the processing result. The current correction circuit of claim 2, wherein the plurality of switch control signals further comprise a third switch control signal, a fourth switch control signal, a fifth switch control signal, and a sixth switch control signal. And the core unit includes: an amplifier having a first input port, a second input port, and an output port, wherein the second input port is coupled to the reference voltage terminal; a second capacitor coupled to the a first input port and the output port; a third capacitor coupled between the first input port and a second specific terminal; a third switch switch selectively selected according to the third switch control signal Coupling the current source to the first input port; a fourth switch switch selectively coupling the predetermined reference voltage input to the second specific end point according to the fourth switch control signal; The switch is configured to selectively couple the first input port to the output port according to the fifth switch control signal; and a sixth switch switch to selectively select the second block according to the sixth switch control signal The fixed end is coupled to the reference voltage terminal. The current correction circuit of claim 6, wherein the fourth switch control signal and the sixth switch control signal are non-overlapping signals, and the third switch control signal and the fifth switch control signal are non-overlapping signals. The first switch control signal, the third switch control signal, and the fourth switch control signal are at least partially overlapped, and the second switch control signal, the fifth switch control signal, and the sixth switch control signal system At least partially overlap. The current correction circuit of claim 7, wherein the first switch is switched from the closed state to the open state after the third switch and the fourth switch are switched from the closed state to the open state. . The current correction circuit of claim 7, wherein the second switch is switched from the closed state to the open state after the fifth switch is switched from the closed state to the open state. The current correction circuit of claim 1, wherein the adjustment function block comprises: an amplifier having a first input port, a second input port, and an output port, wherein the first input port is configured to receive As a result of the processing, the output is used to output the adjustment signal, and the second input port is coupled to a reference voltage terminal; and a capacitor is coupled between the first input port and the output port. The current correction circuit of claim 1, wherein the predetermined reference voltage input is an energy bandgap reference voltage. A current correction method for adjusting a current input generated by a current source, comprising: generating a processing result according to a predetermined reference voltage input and the current input generated by the current source; And generating, according to the processing result, an adjustment signal to the current source to adjust the current input generated by the current source, such that a magnitude of the current input generated by the current source and a magnitude of the predetermined reference voltage input are Predetermined ratio. A ramp generator includes: a current source for generating a current input; and a current correction circuit for adjusting the current input generated by the current source, comprising: a processing function block coupled to the current source Receiving a predetermined reference voltage input and the current input generated by the current source, and generating a processing result according to the predetermined reference voltage input and the current input generated by the current source; and an adjustment function block, coupling Connected to the processing function block and the current source for generating an adjustment signal to the current source according to the processing result to adjust the current input generated by the current source, so that the current generated by the current source is input. a predetermined ratio between the size and the predetermined reference voltage input; and a ramp generating circuit coupled to the current source for generating a ramp signal according to the current input adjusted by the current correcting circuit .