Current compensation circuit and operation method of compensation current

Abstract

A current compensation circuit and a method for operating a compensation current, the method for operating a compensation current being used in an analog front end and comprising: sensing a current state and determining whether the current state is a positive or negative current state. Determining an appropriate control signal based on the current state, and if the current state is a negative current state, sending the appropriate control signal to turn on a positive current electronic switch, or if the current state is a positive current state, sending an appropriate control signal to turn on a negative current electronic switch. When the positive current electronic switch is turned on, a positive compensation current flows to offset the negative parasitic current, and when the negative current electronic switch is turned on, a negative compensation current flows to offset the positive parasitic current. The main control unit uses pulse width modulation signals of different widths associated with different current states to send a pulse width modulation signal to turn on the positive current electronic switch or the negative current electronic switch.

Description

Technical Field

[0001] The present invention relates to an analog front end (AFE), and in particular to an analog front end circuit with pulse width modulation current compensation, a current compensation circuit thereof, and an operating method of the compensation current. Background Art

[0002] Reference Figure 1 , which is a diagram of the analog front-end detection circuit 10. When T[n] receives the sensing signal source, it converts the signal into a current I sense and stores it in the integrator 20. Unfortunately, there are many parasitic capacitors in the detection path, which makes the detection current sense Become I sense +I other To offset I other Excess current, the existing technology adds a capacitor compensation circuit C comp . Compensation current I comp is achieved by compensating for the high voltage (V comph ) and compensate for low voltage (V compl ) is generated by voltage switching.

[0003] This will result in the compensation capacitor having an excessively large value, causing the layout area to have a large area of ​​capacitance and negatively impacting circuit performance.

[0004] Therefore, in order to overcome the shortcomings of the prior art, an analog front-end circuit with pulse width modulation current compensation is needed, which has compensation current in both positive and negative directions. Summary of the Invention

[0005] An object of the present invention is to provide a current compensation circuit for an analog front end (AFE), which uses a pulse width modulation (PWM) signal to generate a positive compensation current and a negative compensation current.

[0006] When V TX When the signal changes from low to high, the integrator senses a positive current. other The current is greater than zero (>0), so the negative compensation current is turned on, and only I sense flows into the integrator.

[0007] When V TX When the signal changes from high to low, the integrator senses a negative current. other The current is less than zero (<0), so the positive compensation current is turned on, and only I sense flows into the integrator.

[0008] As a result, the present invention offsets I by using negative compensation current and positive compensation current.other The excess current is only I sense Flows into the integrator, thus eliminating the negative effects caused by parasitic capacitance on the detection path.

[0009] The present invention provides a current compensation circuit for an analog front end. The current compensation circuit includes a positive current electronic switch connected between a positive voltage supply and a current path; and a negative current electronic switch connected between a ground terminal and the current path.

[0010] In one embodiment, a positive current electronic switch or a negative current electronic switch is turned on based on the sensed current state. When the positive current electronic switch is turned on, a positive compensation current flows. When the negative current electronic switch is turned on, a negative compensation current flows. In one embodiment, a pulse width modulation signal turns on the positive current electronic switch or the negative current electronic switch.

[0011] In one embodiment, a current compensation circuit for an analog front end further includes a main control unit that sends pulse-width modulation signal widths corresponding to positive and negative current compensation states. The main control unit includes a register table containing the pulse-width modulation signal widths corresponding to the positive and negative current compensation states. Based on the sensed current state, the main control unit sends the appropriate pulse-width modulation signal to turn on the positive current electronic switch (PWM-P signal) or the negative current electronic switch (PWM-N signal). In one embodiment, the positive compensation current offsets the negative parasitic current, and the negative compensation current offsets the positive parasitic current.

[0012] The present invention also provides a current compensation circuit for an analog front end. The current compensation circuit includes a first operational amplifier, the first operational amplifier including a first negative input terminal; a first positive input terminal receiving an input voltage signal; and a first output terminal electrically connected to the first negative input terminal. The current compensation circuit also includes a second operational amplifier, the second operational amplifier including a second negative input terminal receiving a reference voltage signal; a second positive input terminal; and a second output terminal. A first capacitor is connected between the second negative input terminal and the second output terminal of the second operational amplifier; and a second capacitor is connected between the second positive input terminal and the second output terminal of the second operational amplifier. The current compensation circuit also includes a positive current electronic switch connected between a positive voltage supply and the second positive input terminal of the second operational amplifier; and a negative current electronic switch connected between ground and the second positive input terminal of the second operational amplifier. In one embodiment, the positive current electronic switch is turned on by a pulse-width modulation signal. In one embodiment, the negative current electronic switch is turned on by a pulse-width modulation signal.

[0013] In one embodiment, a current compensation circuit for an analog front end further includes a main control unit that sends pulse width modulation signal widths corresponding to positive and negative current compensation states. The main control unit includes a register table containing pulse width modulation signal widths corresponding to the positive and negative current compensation states. Based on the sensed state, the main control unit sends an appropriate pulse width modulation signal (PWM-P signal or PWM-N signal) to turn on the positive current electronic switch (PWM-P signal) or the negative current electronic switch (PWM-N signal). When the positive current electronic switch is turned on, a positive compensation current flows from the positive voltage supply to the second positive input terminal. The positive compensation current offsets the negative parasitic current. When the negative current electronic switch is turned on, a negative compensation current flows from the second positive input terminal to ground. The negative compensation current offsets the positive parasitic current.

[0014] In one embodiment, the current compensation circuit for the analog front end is integrated into an integrated circuit.

[0015] The present invention also provides a method for operating a compensation current for use in an analog front-end circuit. The method includes sensing a current state in the analog front-end circuit; determining an appropriate signal based on the current state; sending an appropriate signal to turn on an electronic switch; and allowing the compensation current to flow to offset the parasitic current. If the current state indicates that the parasitic current is less than zero, an appropriate signal is sent to turn on the electronic switch, allowing the positive compensation current to flow. If the current state indicates that the parasitic current is greater than zero, an appropriate signal is sent to turn on the electronic switch, allowing the negative compensation current to flow. In one embodiment, a main control unit determines the current state and uses pulse width modulation signals with different widths to send a pulse width modulation signal to turn on the positive electronic switch or the negative electronic switch. The main control unit determines the current state and uses a register table with different pulse width modulation widths to determine the appropriate signal to send.

[0016] The present invention also provides a method for operating a compensation current for use in an analog front-end circuit. The method includes sensing a current state in the analog front-end circuit; determining whether the current state is positive or negative; determining an appropriate control signal based on the current state; if the current state is negative, sending an appropriate control signal to turn on a positive current electronic switch; if the current state is positive, sending an appropriate control signal to turn on a negative current electronic switch; when the positive current electronic switch is turned on, allowing a positive compensation current to flow to offset a negative parasitic current; and when the negative current electronic switch is turned on, allowing a negative compensation current to flow to offset a positive parasitic current. In one embodiment, a main control unit determines the current state and uses pulse width modulation signals with different widths to send a pulse width modulation signal to turn on the positive electronic switch or the negative electronic switch. The main control unit uses a register table with different pulse width modulation widths to determine the appropriate control signal to send. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A diagram of an analog front-end detection circuit in the prior art;

[0018] Figure 2A A diagram of an analog front end of a current compensation circuit according to a specific embodiment of the present invention;

[0019] Figure 2B is a diagram of an analog front end of a negative current compensation circuit according to a specific embodiment of the present invention;

[0020] Figure 2C is a diagram of an analog front end of a positive current compensation circuit according to a specific embodiment of the present invention;

[0021] Figure 3 The flow chart of the operation method of compensating current in an analog front-end circuit according to a specific embodiment of the present invention is as follows: Figure 1 ;

[0022] Figure 4 Flowchart 2 of a method for compensating current in an analog front-end circuit according to a specific embodiment of the present invention;

[0023] Figure 5 is a timing diagram of a negative current compensation signal according to a specific embodiment of the present invention;

[0024] Figure 6 FIG. 4 is a timing diagram of a positive current compensation signal according to a specific embodiment of the present invention.

[0025] Reference numerals

[0026] 10 Analog front-end detection circuit

[0027] 20 Integrator

[0028] 200 Pulse Width Modulation Current Compensation Circuit

[0029] 210 First operational amplifier

[0030] 230 Second operational amplifier

[0031] 240 Positive current electronic switch

[0032] 250 Negative Current Electronic Switch

[0033] 260 Main Control Unit (MCU)

[0034] 300 Compensation Current Operation Method

[0035] Steps 310-340

[0036] 400 Compensation Current Operation Method

[0037] Steps 410-470 DETAILED DESCRIPTION

[0038] In order to facilitate understanding of the purpose, features and effects of the present invention, specific embodiments and drawings are provided below for detailed description of the present invention.

[0039] Reference Figure 2A , which is a diagram of an analog front end of a current compensation circuit according to a specific embodiment of the present invention.

[0040] The analog front end has a pulse width modulation current compensation circuit 200, including a first operational amplifier 210, a second operational amplifier 230, a positive current electronic switch 240, and a negative current electronic switch 250. The first operational amplifier 210 and the second operational amplifier 230 function as integrators.

[0041] The first operational amplifier 210 includes a first negative input terminal and a first positive input terminal. The first positive input terminal receives an input voltage signal V TX The first operational amplifier 210 further includes a first positive output terminal electrically connected to the first negative input terminal.

[0042] The second operational amplifier 230 includes a second negative input terminal, which receives a reference voltage signal V ref The second operational amplifier 230 further includes a second positive input terminal, a second positive output terminal, and a second negative output terminal. F1 Connected between the second negative input terminal and the second positive output terminal. The second positive output terminal is used to output a positive output voltage signal (V OP[n]The second feedback capacitor CF2 is connected between the second positive input terminal and the second negative output terminal. The second negative output terminal is used to output a negative output voltage signal (V ON[n] ).

[0043] The first positive output terminal of the first operational amplifier 210 is electrically connected to the second positive input terminal of the second operational amplifier 230 .

[0044] The positive current electronic switch 240 is connected between the positive voltage supply and the second positive input terminal.

[0045] The negative current electronic switch 250 is connected between the ground terminal and the second positive input terminal.

[0046] The pulse width modulated signal turns on the positive current electronic switch 240 or the negative current electronic switch 250. The pulse width modulated positive signal (PWM-P signal) turns on the positive current electronic switch 240. The pulse width modulated negative signal (PWM-N signal) turns on the negative current electronic switch 250.

[0047] When the positive current electronic switch 240 is turned on, the positive compensation current (I comp-p ) flows from the positive voltage supply to the second positive input terminal. Positive compensation current (I comp-p ) offsets the negative parasitic current.

[0048] When the negative current electronic switch 250 is turned on, the negative compensation current (I comp-n ) flows from the second positive input terminal to the ground terminal. Negative compensation current (I comp-n ) offsets the positive parasitic current.

[0049] When T[n] receives a sense signal source, it converts the signal into a current I sense and loads it into the first operational amplifier 210. Unfortunately, there are many parasitic capacitors in the detection path, which makes the detection current sense Become I sense +I other To offset I other To compensate for the excess current, the analog front end with a pulse width modulation current compensation circuit generates positive compensation current and negative compensation current using a pulse width modulation (PWM) signal.

[0050] Reference Figure 2B , which is a diagram of an analog front end with a pulse width modulation negative current compensation circuit according to a specific embodiment of the present invention.

[0051] When V TX When the signal (at the first positive input terminal of the first operational amplifier 210) changes from low to high, the first operational amplifier 210 senses a positive current. otherThe current is greater than zero (>0), so the negative current electronic switch 250 is turned on, and the negative compensation current I comp-n The negative current flows from the second positive input terminal of the second operational amplifier 230 to the ground terminal through the negative current electronic switch 250 .

[0052] As a result, the present invention can be implemented by using the negative compensation current I comp-n To offset I other Excess current, and only I sense The voltage flows into the second operational amplifier 230, thereby eliminating the negative impact caused by the parasitic capacitance on the detection path.

[0053] Reference Figure 2C , which is a diagram of an analog front end with a pulse width modulation positive current compensation circuit according to a specific embodiment of the present invention.

[0054] When V TX When the signal (at the first positive input terminal of the first operational amplifier 210) changes from high to low, the first operational amplifier 210 senses a negative current. other The current is less than zero (<0), so the positive current electronic switch 240 is turned on, and the positive compensation current I comp-p The positive current flows from the positive voltage supply through the positive current electronic switch 240 to the second positive input terminal of the second operational amplifier 230 .

[0055] As a result, the present invention can be implemented by using the positive compensation current I comp-p To offset I other Excess current, and only I sense The voltage flows into the second operational amplifier 230, thereby eliminating the negative impact caused by the parasitic capacitance on the detection path.

[0056] Reference Figure 3 , which is a flow chart of an operation method for compensating current in an analog front-end circuit according to a specific embodiment of the present invention Figure 1 .

[0057] In a specific embodiment, the present invention also provides an operating method 300 for compensating current in an analog front-end circuit, which includes sensing the current state in the analog front-end circuit in step 310. In step 320, determining an appropriate signal based on the sensed current state. In step 330, sending an appropriate signal to turn on the electronic switch. In step 340, allowing the compensation current to flow to offset any parasitic current. If in step 310, the current state indicates that the parasitic current is less than zero, sending an appropriate signal (pwm-p signal) to turn on the positron switch and allow the positive compensation current to flow. If in step 310, the current state indicates that the parasitic current is greater than zero, sending an appropriate signal (pwm-n signal) to turn on the negative electron switch and allow the negative compensation current to flow. In a specific embodiment, referring to Figure 2A 、 Figure 2B 、 Figure 2C The master control unit (MCU) 260 determines the current state and sends a pulse-width modulated signal with different widths to turn on the positronic switch or the epsilon switch. The MCU uses a register table with different pulse-width modulation widths associated with different current states to determine the appropriate control signal to send.

[0058] Reference Figure 4 , which is a second flowchart of an operating method for compensating current in an analog front-end circuit according to a specific embodiment of the present invention.

[0059] The present invention also provides an operating method 400 for compensating current in an analog front-end circuit, which includes, in step 410, sensing the current state in the analog front-end circuit. In step 420, determining whether the current state is a positive current state or a negative current state. Then, in step 430, determining an appropriate control signal based on the sensed current state. In step 440, if the current state is a negative current state, sending an appropriate control signal to turn on the positive current electronic switch. In step 450, if the current state is a positive current state, sending an appropriate control signal to turn on the negative current electronic switch. In step 460, when the positive current electronic switch is turned on, a positive compensation current is allowed to flow to offset the negative parasitic current. In step 470, when the negative current electronic switch is turned on, a negative compensation current is allowed to flow to offset the positive parasitic current.

[0060] In one embodiment, the main control unit determines the current state and uses pulse width modulation signals with different widths to transmit pulse width modulation signals to turn on the positronic switch or the epsilonic switch. The main control unit uses a register table to determine the appropriate control signal to transmit, wherein the register table has different pulse width modulation widths associated with different current states.

[0061] Reference Figure 5 , which is a timing diagram of a negative current compensation signal according to a specific embodiment of the present invention.

[0062] like Figure 5 As shown, when I other Greater than zero (I other >0), the main control unit sends a pulse width modulation signal (pwm-n) to turn on the negative current electronic switch and enable the compensation current I comp-n To compensate. other *T sense –I comp-n *T pwm-n =0.

[0063] Reference Figure 6 , which is a timing diagram of a positive current compensation signal according to a specific embodiment of the present invention.

[0064] like Figure 6 As shown, when I other Less than zero (I other <0), the main control unit sends a pulse width modulation signal (PWM-P) to turn on the positive current electronic switch and enable the compensation current I comp-p To compensate. other *T sense +I comp-p *T pwm-p =0.

[0065] Although the present invention has been described through specific embodiments, those skilled in the art may make many modifications and variations to these embodiments without departing from the scope and spirit of the invention as defined by the claims.

Claims

1. A current compensation circuit for an analog front end, characterized in that: The current compensation circuit includes: Operational amplifiers; a positive current electronic switch, the positive current electronic switch being directly connected between a positive voltage supply and being electrically connected to a positive input terminal of the operational amplifier; and a negative current electronic switch, the negative current electronic switch being directly connected to a ground terminal and electrically connected between the positive input terminal of the operational amplifier; wherein the positive current electronic switch or the negative current electronic switch is turned on according to the sensed current state; wherein when the positive current electronic switch is turned on, a positive compensation current flows; and When the negative current electronic switch is turned on, a negative compensation current flows. The current compensation circuit offsets excess current by using the positive compensation current and the negative compensation current.

2. The current compensation circuit according to claim 1, characterized in that: The pulse width modulation signal turns on the positive current electronic switch or the negative current electronic switch.

3. The current compensation circuit according to claim 1, wherein: The current compensation circuit further includes: a main control unit, the main control unit including a register table containing pulse width modulation signal widths corresponding to positive and negative current compensation states; According to the sensed current state, the main control unit sends an appropriate pulse width modulation signal to turn on the positive current electronic switch or the negative current electronic switch.

4. The current compensation circuit according to claim 1, wherein: The positive compensation current offsets the negative parasitic current.

5. The current compensation circuit according to claim 1, wherein: The negative compensation current offsets the positive parasitic current.

6. A current compensation circuit for an analog front end, characterized in that: The current compensation circuit includes: A first operational amplifier, the first operational amplifier comprising: a first negative input terminal; a first positive input terminal, the first positive input terminal receiving an input voltage signal; and a first output terminal electrically connected to the first negative input terminal; A second operational amplifier, the second operational amplifier comprising: a second negative input terminal, wherein the second negative input terminal receives a reference voltage signal; a second positive input terminal; and a second output terminal; a first capacitor connected between the second negative input terminal and the second output terminal; a second capacitor connected between the second positive input terminal and the second output terminal; a positive current electronic switch connected between a positive voltage supply and the second positive input terminal; and A negative current electronic switch is connected between the ground terminal and the second positive input terminal.

7. The current compensation circuit according to claim 6, characterized in that: The positive current electronic switch is turned on by a pulse width modulation signal.

8. The current compensation circuit according to claim 6, wherein: The negative current electronic switch is turned on by a pulse width modulation signal.

9. The current compensation circuit according to claim 6, wherein: The current compensation circuit further includes: a main control unit, the main control unit including a register table containing pulse width modulation signal widths corresponding to positive and negative current compensation states; Wherein, according to the sensing state, the main control unit sends an appropriate pulse width modulation signal, to turn on the positive current electronic switch or the negative current electronic switch.

10. The current compensation circuit according to claim 6, wherein: When the positive current electronic switch is turned on, a positive compensation current flows from the positive voltage supply to the second positive input terminal.

11. The current compensation circuit according to claim 10, characterized in that: The positive compensation current offsets the negative parasitic current.

12. The current compensation circuit according to claim 6, wherein: When the negative current electronic switch is turned on, a negative compensation current flows from the second positive input terminal to the ground terminal.

13. The current compensation circuit according to claim 12, wherein: The negative compensation current offsets the positive parasitic current.

14. A current compensation circuit for an analog front end, characterized in that: The current compensation circuit includes: A first operational amplifier, the first operational amplifier comprising: a first negative input terminal; a first positive input terminal, the first positive input terminal receiving an input voltage signal; and a first output terminal electrically connected to the first negative input terminal; A second operational amplifier, the second operational amplifier comprising: a second negative input terminal, wherein the second negative input terminal receives a reference voltage signal; a second positive input terminal; and a second output terminal; a positive current electronic switch connected between the positive voltage supply and the second positive input terminal; a negative current electronic switch connected between the ground terminal and the second positive input terminal; and a main control unit, the main control unit including a register table containing pulse width modulation signal widths corresponding to positive and negative current compensation states; Wherein, according to the sensing state, the main control unit sends an appropriate pulse width modulation signal, to turn on the positive current electronic switch or the negative current electronic switch.

15. The current compensation circuit according to claim 14, wherein: The current compensation circuit further includes: A first capacitor is connected between the second negative input terminal and the second output terminal; and The second capacitor is connected between the second positive input terminal and the second output terminal.

16. The current compensation circuit according to claim 14, wherein: When the positive current electronic switch is turned on, a positive compensation current flows from the positive voltage supply to the second positive input terminal.

17. The current compensation circuit according to claim 16, wherein: The positive compensation current offsets the negative parasitic current.

18. The current compensation circuit according to claim 14, wherein: When the negative current electronic switch is turned on, a negative compensation current flows from the second positive input terminal to the ground terminal.

19. The current compensation circuit according to claim 18, wherein: The negative compensation current offsets the positive parasitic current.

Images