Anti-aliasing filter with high roll-off coefficient and testing machine

Abstract

The utility model relates to an anti-aliasing filter with a high roll-off coefficient and a testing machine, and the filter comprises a first-stage operational amplifier module which is connected with a first analog signal, amplifies the first analog signal, and outputs the amplified first analog signal; the impedance conversion filtering module is connected with the first-stage operational amplifier module, and is used for performing impedance conversion and filtering on the signal output by the first-stage operational amplifier module and then outputting the signal; the second-stage operational amplifier module is connected with the impedance conversion filtering module and the output end of the filter, receives the signal output by the impedance conversion filtering module for signal processing, and outputs the processed signal to the output end of the filter; and the wave trap is connected between the second-stage operational amplifier module and the output end of the filter. The wave trap is designed between the second-stage operational amplifier module and the output end of the filter, the suppression capability of a transition zone can be effectively improved, a good roll-off coefficient is achieved in the transition zone, compared with a cavity filter, the size is small, and the design difficulty is reduced.

Description

Technical Field

[0001] The present application relates to the field of semiconductor testing technology, and in particular to an anti-aliasing filter with a high roll-off coefficient and a testing machine. Background Art

[0002] Semiconductor automated testing refers to the use of automatic test equipment (ATE) to test various parameters of the device under test (DUT) to eliminate defective products and control the quality of semiconductor devices before they leave the factory. Filters are often used in testers for signal suppression. In traditional solutions, filters are designed as cavity filters. Since cavity filters are very large, especially in low-frequency filter design, it is difficult to implement on-board design, which has the disadvantage of high design difficulty. Utility Model Content

[0003] Based on this, it is necessary to provide an anti-aliasing filter and a test machine with a high roll-off coefficient that can reduce the difficulty of design in order to address the above problems.

[0004] The first aspect of the present application provides an anti-aliasing filter with a high roll-off coefficient, comprising:

[0005] The first stage operational amplifier module receives the first analog signal, amplifies the first analog signal and then outputs it;

[0006] An impedance transformation and filtering module, connected to the first-stage operational amplifier module, performs impedance transformation and filtering on the signal output by the first-stage operational amplifier module and then outputs the signal;

[0007] The second stage operational amplifier module is connected to the impedance transformation filter module and the filter output end, receives the signal output by the impedance transformation filter module for signal processing, and outputs the processed signal to the filter output end;

[0008] A notch filter is connected between the second-stage operational amplifier module and the output end of the filter.

[0009] In one embodiment, the first-stage operational amplifier module includes an amplifier U1, a resistor R1 and a resistor R2, the non-inverting input terminal of the amplifier U1 is connected to the first analog signal, the inverting input terminal of the amplifier U1 is connected to the first end of the resistor R1 and the first end of the resistor R2, the second end of the resistor R1 is grounded, the second end of the resistor R2 is connected to the output end of the amplifier U1, and the output end of the amplifier U1 is connected to the impedance transformation filter module.

[0010] In one embodiment, the impedance transformation filter module includes a resistor R3, a resistor R5 and a filter component, the first end of the resistor R3 is connected to the first-stage operational amplifier module, the second end of the resistor R3 is connected to the filter component, the filter component is connected to the first end of the resistor R5 and the second-stage operational amplifier module, and the second end of the resistor R5 is grounded.

[0011] In one embodiment, the filter component is a multi-stage filter component.

[0012] In one embodiment, the multi-stage filtering component includes a first filtering element, a second filtering element, a third filtering element and a fourth filtering element connected in sequence, the first filtering element is connected to the second end of the resistor R3, and the fourth filtering element is connected to the first end of the resistor R5 and the second-stage operational amplifier module.

[0013] In one embodiment, the first filter element includes an inductor L1 and a capacitor C1, the second filter element includes an inductor L2 and a capacitor C2, the third filter element includes an inductor L3 and a capacitor C3, and the fourth filter element includes an inductor L4 and a capacitor C4;

[0014] The first end of the inductor L1 is connected to the second end of the resistor R3, the second end of the inductor L1 is connected to the first end of the inductor L2, the second end of the inductor L2 is connected to the first end of the inductor L3, the second end of the inductor L3 is connected to the first end of the inductor L4, and the second end of the inductor L4 is connected to the first end of the resistor R5 and the second-stage operational amplifier module; the first end of the capacitor C1 is connected to the second end of the inductor L1, the second end of the capacitor C1 is grounded, the first end of the capacitor C2 is connected to the second end of the inductor L2, and the second end of the capacitor C2 is grounded; the first end of the capacitor C3 is connected to the second end of the inductor L3, the second end of the capacitor C3 is grounded, the first end of the capacitor C4 is connected to the second end of the inductor L4, and the second end of the capacitor C4 is grounded.

[0015] In one embodiment, the second-stage operational amplifier module includes an amplifier U2, a resistor R6, a resistor R7, a resistor R9 and a resistor R15, the in-phase input terminal of the amplifier U2 is connected to the first end of the resistor R7, the inverting input terminal of the amplifier U2 is connected to the first end of the resistor R6, the second end of the resistor R7 is grounded, and the second end of the resistor R6 is connected to the impedance transformation filter module; the first end of the resistor R9 is connected to the inverting input terminal of the amplifier U2, the second end of the resistor R9 is connected to the output terminal of the amplifier U2, the output terminal of the amplifier U2 is connected to the first end of the resistor R15, and the second end of the resistor R15 is connected to the filter output terminal.

[0016] In one embodiment, the trap includes an inductor L5, a capacitor C6, a capacitor C7, a switching unit, a resistor R17 and a resistor R18, the first end of the inductor L5 is connected to the second-stage operational amplifier module and the filter output end, the second end of the inductor L5 is connected to the first end of the capacitor C6 and the first end of the capacitor C7, the second end of the capacitor C6 and the second end of the capacitor C7 are connected to the switching unit, the switching unit is connected to the first end of the resistor R17 and the first end of the resistor R18, and the second end of the resistor R17 and the second end of the resistor R18 are both grounded.

[0017] In one embodiment, the switching unit includes a switch U4 and a switch U5, and the switch U4 and the switch U5 both include a static contact, a first moving contact, and a second moving contact; the static contact of the switch U4 is connected to the second end of the capacitor C6, the first moving contact of the switch U4 is connected to the first end of the resistor R17, and the second moving contact of the switch U4 is connected to the first end of the resistor R18; the static contact of the switch U5 is connected to the second end of the capacitor C7, the first moving contact of the switch U5 is connected to the first end of the resistor R17, and the second moving contact of the switch U5 is connected to the first end of the resistor R18.

[0018] A second aspect of the present application provides a test machine, comprising the above-mentioned anti-aliasing filter with a high roll-off coefficient.

[0019] In one embodiment, the test machine is a digital test machine.

[0020] In the above-mentioned anti-aliasing filter and test machine with a high roll-off coefficient, the first-stage operational amplifier module amplifies the first analog signal and then outputs it, and the impedance transformation filter module performs impedance transformation and filtering on the signal output by the first-stage operational amplifier module and then outputs it. The second-stage operational amplifier module receives the signal output by the impedance transformation filter module for signal processing, and outputs the processed signal to the filter output end, and the notch filter is connected between the second-stage operational amplifier module and the filter output end. Designing a notch filter between the second-stage operational amplifier module and the filter output end can effectively improve the suppression ability of the transition band, and has a good roll-off coefficient in the transition band. Compared with the cavity filter, it is small in size and reduces the design difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a structural block diagram of an anti-aliasing filter with a high roll-off coefficient in one embodiment;

[0022] Figure 2 is a structural schematic diagram of a first-stage operational amplifier module in an embodiment;

[0023] Figure 3 A structural schematic diagram of an impedance transformation filter module in an embodiment;

[0024] Figure 4 A schematic diagram of the performance of an adjustable input and output impedance filter in one embodiment;

[0025] Figure 5 is a structural schematic diagram of a second-stage operational amplifier module and a notch filter in one embodiment;

[0026] Figure 6 FIG. 4 is a schematic diagram of the performance of an adjustable notch filter in one embodiment. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0029] It is understood that the terms "first", "second", etc. used in this application can be used to describe various elements in this article, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. The "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if the connected circuits, modules, units, etc. have transmission of electrical signals or data with each other.

[0030] When used herein, the singular forms "a", "an", and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0031] In one embodiment, Figure 1As shown, an anti-aliasing filter with a high roll-off coefficient is provided, including a first-stage operational amplifier module 110, an impedance conversion filter module 120, a second-stage operational amplifier module 130 and a notch filter 140, wherein the impedance conversion filter module 120 is connected to the first-stage operational amplifier module 110, the second-stage operational amplifier module 130 is connected to the impedance conversion filter module 120 and the filter output end, and the notch filter 140 is connected between the second-stage operational amplifier module 130 and the filter output end. The first-stage operational amplifier module 110 receives a first analog signal, amplifies the first analog signal and outputs it, and the impedance conversion filter module 120 performs impedance conversion and filtering on the signal output by the first-stage operational amplifier module 110 and outputs it. The second-stage operational amplifier module 130 receives the signal output by the impedance conversion filter module 120 for signal processing, and outputs the processed signal to the filter output end.

[0032] Specifically, the first-stage operational amplifier module 110, as the front-stage circuit of the filter, amplifies the input first analog signal to provide a certain gain, and then performs impedance transformation and signal filtering through the impedance transformation filter module 120. The second-stage operational amplifier module 130, as the rear-stage circuit of the filter, amplifies or adds the connected signal, and outputs the processed analog signal, which can simultaneously meet the signal output and filtering of the single-ended and differential modes. A notch filter is designed at the back end of the second-stage operational amplifier module 130, so that the transition band of the filter has a greater suppression ability, and can achieve a higher roll-off factor while achieving a high suppression degree (80db), further improving the transition band suppression ability of the filter.

[0033] In one embodiment, Figure 2 As shown, the first-stage operational amplifier module 110 includes an amplifier U1, a resistor R1 and a resistor R2, the in-phase input terminal IN+ of the amplifier U1 is connected to the first analog signal, the inverting input terminal IN- of the amplifier U1 is connected to the first end of the resistor R1 and the first end of the resistor R2, the second end of the resistor R1 is grounded, the second end of the resistor R2 is connected to the output end of the amplifier U1, and the output end of the amplifier U1 is connected to the impedance conversion filter module 120. Among them, the signal A represents the first analog signal connected, and the signal A' represents the signal output by the first-stage operational amplifier module 110. The in-phase input terminal IN+ of the amplifier U1 can also be provided with a 100 ohm resistor, and the first analog signal is connected through the 100 ohm resistor. The amplifier U1 is a in-phase proportional operational amplifier, which amplifies the input first analog signal, provides a certain gain, and changes the input impedance of the signal.

[0034] like Figure 3As shown, the impedance transformation filter module 120 includes a resistor R3, a resistor R5 and a filter component 122, the first end of the resistor R3 is connected to the first-stage operational amplifier module 110, the second end of the resistor R3 is connected to the filter component 122, the filter component 122 is connected to the first end of the resistor R5 and the second-stage operational amplifier module 130, and the second end of the resistor R5 is grounded. Among them, the first end of the resistor R3 is specifically connected to the output end of the amplifier U1 in the first-stage operational amplifier module 110. The impedance of the signal A' is transformed by the resistor R3, the output resistance of the operational amplifier is adjusted, and then the signal is subjected to multi-stage low-pass filtering by the filter component 122, and the signal A" is output to the second-stage operational amplifier module 130. Furthermore, the structure of the filter component 122 is not unique, and can be a single-stage filtering structure or a multi-stage filtering structure. In this embodiment, the filter component 122 is a multi-stage filtering component. The multi-stage filtering component may specifically include but is not limited to a first filtering element 1222, a second filtering element 1224, a third filtering element 1226 and a fourth filtering element 1228 connected in sequence, the first filtering element 1222 is connected to the second end of the resistor R3, and the fourth filtering element 1228 is connected to the first end of the resistor R5 and the second-stage operational amplifier module 130.

[0035] In one embodiment, the first filter element 1222 includes an inductor L1 and a capacitor C1, the second filter element 1224 includes an inductor L2 and a capacitor C2, the third filter element 1226 includes an inductor L3 and a capacitor C3, and the fourth filter element 1228 includes an inductor L4 and a capacitor C4. The first end of the inductor L1 is connected to the second end of the resistor R3, the second end of the inductor L1 is connected to the first end of the inductor L2, the second end of the inductor L2 is connected to the first end of the inductor L3, the second end of the inductor L3 is connected to the first end of the inductor L4, and the second end of the inductor L4 is connected to the first end of the resistor R5 and the second stage operational amplifier module 130. The first end of the capacitor C1 is connected to the second end of the inductor L1, the second end of the capacitor C1 is grounded, the first end of the capacitor C2 is connected to the second end of the inductor L2, and the second end of the capacitor C2 is grounded; the first end of the capacitor C3 is connected to the second end of the inductor L3, the second end of the capacitor C3 is grounded, the first end of the capacitor C4 is connected to the second end of the inductor L4, and the second end of the capacitor C4 is grounded.

[0036] Among them, after the signal A' is subjected to impedance transformation by the resistor R3, it is subjected to Bessel multi-stage low-pass filtering by the inductors L1, L2, L3, L4 and the capacitors C1, C2, C3 and C4, and the filtered signal A" is transmitted to the second-stage operational amplifier module 130. The impedance of the subsequent operational amplifier can be matched by adjusting the resistance value of R5. Figure 4 This is a performance diagram of an adjustable input and output impedance filter. By adjusting the resistance values ​​of resistors R3 and R5, the impedances of the front-stage circuit and the rear-stage circuit of the filter can be well matched.

[0037] In one embodiment, Figure 5 As shown, the second-stage operational amplifier module 130 includes an amplifier U2, a resistor R6, a resistor R7, a resistor R9 and a resistor R15. The in-phase input terminal IN+ of the amplifier U2 is connected to the first end of the resistor R7, the inverting input terminal IN- of the amplifier U2 is connected to the first end of the resistor R6, the second end of the resistor R7 is grounded, and the second end of the resistor R6 is connected to the impedance transformation filter module 120; the first end of the resistor R9 is connected to the inverting input terminal IN- of the amplifier U2, the second end of the resistor R9 is connected to the output end of the amplifier U2, the output end of the amplifier U2 is connected to the first end of the resistor R15, and the second end of the resistor R15 is connected to the output end of the filter.

[0038] Specifically, signal B represents the analog signal output from the output end of the filter. Amplifier U2 is an in-phase proportional operational amplifier, and the second end of resistor R6 is connected to the second end of inductor L4 in impedance transformation filter module 120. Signal A'' filtered by filter component 122 is amplified or added by amplifier U2, and the processed signal is transformed into output impedance by resistor R15 to achieve the required output impedance.

[0039] In one embodiment, continue to refer to Figure 5 The wave trap 140 includes an inductor L5, a capacitor C6, a capacitor C7, a switching unit 142, a resistor R17, and a resistor R18. The first end of the inductor L5 is connected to the second-stage operational amplifier module 130 and the filter output end. The second end of the inductor L5 is connected to the first end of the capacitor C6 and the first end of the capacitor C7. The second end of the capacitor C6 and the second end of the capacitor C7 are connected to the switching unit 142. The switching unit 142 is connected to the first end of the resistor R17 and the first end of the resistor R18. The second end of the resistor R17 and the second end of the resistor R18 are both grounded. Among them, the first end of the inductor L5 is specifically connected to the second end of the resistor R15 in the second-stage operational amplifier module 130. The resistance values ​​of the resistor R17 and the resistor R18 can be designed to be different, and the switch selection is performed by the switching unit 142, and the resistor R17 or the resistor R18 is cut into the circuit to achieve different wave trap effects. Figure 6 This is a performance diagram of an adjustable notch filter. Designing a notch filter at the back end of the op amp output can effectively improve the suppression capability of the transition band of the previous filter. For example, if the previous filter is an 80M filter, the attenuation band of the notch filter starts from 80M, and the filtering effect is very obvious.

[0040] Further, the switching unit 142 may specifically include a switch U4 and a switch U5, and the switch U4 and the switch U5 each include a static contact, a first moving contact, and a second moving contact. The static contact of the switch U4 is connected to the second end of the capacitor C6, the first moving contact of the switch U4 is connected to the first end of the resistor R17, and the second moving contact of the switch U4 is connected to the first end of the resistor R18; the static contact of the switch U5 is connected to the second end of the capacitor C7, the first moving contact of the switch U5 is connected to the first end of the resistor R17, and the second moving contact of the switch U5 is connected to the first end of the resistor R18. By controlling the switch U4 and the switch U5, the static contact and the first moving contact are switched on at the same time, or the static contact and the second moving contact are switched on at the same time, so that the resistor R17 or the resistor R18 is connected to the circuit to achieve different trapping effects.

[0041] In one embodiment, a test machine is also provided, comprising the above-mentioned anti-aliasing filter with a high roll-off coefficient. The test machine can be a digital test machine or other types of test machines.

[0042] The above-mentioned high roll-off coefficient anti-aliasing filter and test machine can achieve 80db suppression and high roll-off coefficient of 0Hz-100MHz wideband signal out-band, and have excellent performance in signal flatness, which is a very outstanding performance among existing products. The filter and test machine have the following advantages:

[0043] 1. High suppression, able to achieve 80db suppression capability, and a good roll-off coefficient in the transition zone, which is very popular in applications with increasingly higher filtering performance, and can achieve filtering of large and small signals at the same time, which is essential in the design of automation equipment.

[0044] 2. Reduced signal phase deviation. The use of Bessel filters has little effect on the group delay of the signal, achieving high fidelity of the signal.

[0045] 3. Adjustable input and output impedance greatly improves the application of the filter.

[0046] 4. High roll-off coefficient. The combination of notch filter and filter makes the roll-off coefficient of the filter higher.

[0047] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0048] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. An anti-aliasing filter with a high roll-off coefficient, characterized in that: include: The first stage operational amplifier module receives the first analog signal, amplifies the first analog signal and then outputs it; An impedance transformation and filtering module, connected to the first-stage operational amplifier module, performs impedance transformation and filtering on the signal output by the first-stage operational amplifier module and then outputs the signal; The second stage operational amplifier module is connected to the impedance transformation filter module and the filter output end, receives the signal output by the impedance transformation filter module for signal processing, and outputs the processed signal to the filter output end; A notch filter is connected between the second-stage operational amplifier module and the output end of the filter.

2. The anti-aliasing filter according to claim 1, characterized in that The first-stage operational amplifier module includes an amplifier U1, a resistor R1 and a resistor R2. The in-phase input terminal of the amplifier U1 is connected to the first analog signal, the inverting input terminal of the amplifier U1 is connected to the first end of the resistor R1 and the first end of the resistor R2, the second end of the resistor R1 is grounded, the second end of the resistor R2 is connected to the output end of the amplifier U1, and the output end of the amplifier U1 is connected to the impedance transformation filter module.

3. The anti-aliasing filter according to claim 1, characterized in that The impedance transformation filter module includes a resistor R3, a resistor R5 and a filter component, the first end of the resistor R3 is connected to the first-stage operational amplifier module, the second end of the resistor R3 is connected to the filter component, the filter component is connected to the first end of the resistor R5 and the second-stage operational amplifier module, and the second end of the resistor R5 is grounded.

4. The anti-aliasing filter according to claim 3, characterized in that The filter component is a multi-stage filter component.

5. The anti-aliasing filter according to claim 4, characterized in that: The multi-stage filter component includes a first filter element, a second filter element, a third filter element and a fourth filter element connected in sequence, the first filter element is connected to the second end of the resistor R3, and the fourth filter element is connected to the first end of the resistor R5 and the second-stage operational amplifier module.

6. The anti-aliasing filter according to claim 5, characterized in that The first filter element includes an inductor L1 and a capacitor C1, the second filter element includes an inductor L2 and a capacitor C2, the third filter element includes an inductor L3 and a capacitor C3, and the fourth filter element includes an inductor L4 and a capacitor C4; The first end of the inductor L1 is connected to the second end of the resistor R3, the second end of the inductor L1 is connected to the first end of the inductor L2, the second end of the inductor L2 is connected to the first end of the inductor L3, the second end of the inductor L3 is connected to the first end of the inductor L4, and the second end of the inductor L4 is connected to the first end of the resistor R5 and the second-stage operational amplifier module; the first end of the capacitor C1 is connected to the second end of the inductor L1, the second end of the capacitor C1 is grounded, the first end of the capacitor C2 is connected to the second end of the inductor L2, and the second end of the capacitor C2 is grounded; the first end of the capacitor C3 is connected to the second end of the inductor L3, the second end of the capacitor C3 is grounded, the first end of the capacitor C4 is connected to the second end of the inductor L4, and the second end of the capacitor C4 is grounded.

7. The anti-aliasing filter according to claim 1, characterized in that: The second-stage operational amplifier module includes an amplifier U2, a resistor R6, a resistor R7, a resistor R9 and a resistor R15. The in-phase input terminal of the amplifier U2 is connected to the first end of the resistor R7, the inverting input terminal of the amplifier U2 is connected to the first end of the resistor R6, the second end of the resistor R7 is grounded, and the second end of the resistor R6 is connected to the impedance transformation filter module; the first end of the resistor R9 is connected to the inverting input terminal of the amplifier U2, the second end of the resistor R9 is connected to the output terminal of the amplifier U2, the output terminal of the amplifier U2 is connected to the first end of the resistor R15, and the second end of the resistor R15 is connected to the filter output terminal.

8. The anti-aliasing filter according to any one of claims 1 to 7, characterized in that: The wave trap includes an inductor L5, a capacitor C6, a capacitor C7, a switching unit, a resistor R17 and a resistor R18, the first end of the inductor L5 is connected to the second-stage operational amplifier module and the filter output end, the second end of the inductor L5 is connected to the first end of the capacitor C6 and the first end of the capacitor C7, the second end of the capacitor C6 and the second end of the capacitor C7 are connected to the switching unit, the switching unit is connected to the first end of the resistor R17 and the first end of the resistor R18, and the second end of the resistor R17 and the second end of the resistor R18 are both grounded.

9. The anti-aliasing filter according to claim 8, characterized in that: The switching unit includes a switch U4 and a switch U5, each of which includes a static contact, a first moving contact, and a second moving contact; the static contact of the switch U4 is connected to the second end of the capacitor C6, the first moving contact of the switch U4 is connected to the first end of the resistor R17, and the second moving contact of the switch U4 is connected to the first end of the resistor R18; the static contact of the switch U5 is connected to the second end of the capacitor C7, the first moving contact of the switch U5 is connected to the first end of the resistor R17, and the second moving contact of the switch U5 is connected to the first end of the resistor R18.

10. A testing machine, characterized in that: An anti-aliasing filter with a high roll-off coefficient comprising any one of claims 1-9.

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