Gain stabilized open loop amplifier
By setting up two open-loop amplifiers with shared power supply and bias signals on the same chip and using a feedback network to achieve closed-loop feedback, the problem of gain instability of open-loop amplifiers under PVT variation is solved, achieving gain stability and wide application.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 归芯科技(深圳)有限公司
- Filing Date
- 2026-03-25
- Publication Date
- 2026-06-19
AI Technical Summary
The gain of open-loop amplifiers is extremely unstable under process-supply voltage-temperature (PVT) variations, which limits their application range.
Two open-loop amplifiers are set on the same chip: one for the successive approximation analog-to-digital converter and the other for the feedback loop. They share the power network and bias signal, and achieve closed-loop feedback through the feedback network to adjust the gain coefficient in real time and ensure gain stability.
By designing shared environmental parameters and a feedback network, the gain stability of the open-loop amplifier under PVT variations was achieved, expanding its application range.
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Figure CN122247362A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor device technology, and more particularly to a gain-stable open-loop amplifier. Background Technology
[0002] Open-loop amplifiers are effective at handling high-speed and very small-amplitude signals due to their high bandwidth potential, low noise performance, and large dynamic range potential. However, while open-loop amplifiers reduce the operational amplifier gain requirements of closed-loop amplifiers and avoid static power consumption, they are extremely sensitive to changes in process-supply voltage-temperature (PVT). This problem causes significant instability in the gain of open-loop amplifiers, limiting their application range. Summary of the Invention
[0003] The open-loop amplifier with stable gain provided by this invention can avoid gain fluctuations in the open-loop amplifier and maintain the gain stability of the open-loop amplifier.
[0004] This invention provides a gain-stable open-loop amplifier, comprising:
[0005] An amplifier circuit comprising two open-loop amplifiers; one open-loop amplifier being used in a successive approximation analog-to-digital converter; and the other open-loop amplifier being used in a feedback loop; wherein the two open-loop amplifiers are located in the same region of the same chip, and the two open-loop amplifiers share a power network and a bias signal; A feedback network is provided, wherein the input terminal of the feedback network is electrically connected to the output terminal of the open-loop amplifier applied to the feedback loop, and the output terminal of the feedback network is electrically connected to the bias signal input terminals of the two open-loop amplifiers, so as to realize closed-loop feedback of the open-loop amplifier applied to the feedback loop.
[0006] Optionally, the input terminal of the open-loop amplifier used in the successive approximation analog-to-digital converter is electrically connected to the preceding successive approximation register module, and the output terminal of the open-loop amplifier used in the successive approximation analog-to-digital converter is electrically connected to the following successive approximation register module.
[0007] Optionally, the feedback network includes: A gain module, wherein the input terminal of the gain module is electrically connected to the output terminal of the open-loop amplifier applied to the feedback loop, wherein the gain coefficient of the gain module is the reciprocal of the target amplification coefficient of the open-loop amplifier applied to the feedback loop; The comparator has a first input terminal electrically connected to the input terminal of the open-loop amplifier applied to the feedback loop, a second input terminal electrically connected to the output terminal of the gain module, and an output signal of the comparator serving as a bias signal electrically connected to the bias signal input terminals of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop.
[0008] Optionally, the feedback network includes: A gain module, the output of which is electrically connected to the input of the open-loop amplifier applied to the feedback loop, wherein the gain coefficient of the gain module is the reciprocal of the target amplification coefficient of the open-loop amplifier applied to the feedback loop; The comparator has its first input terminal electrically connected to the input terminal of the gain module, its second input terminal electrically connected to the output terminal of the open-loop amplifier applied to the feedback loop, and its output signal, as a bias signal, electrically connected to the bias signal input terminals of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop.
[0009] Optionally, the feedback network includes: Two gain modules are provided, one of which is a pre-amplifier gain module, the output of which is electrically connected to the input of the open-loop amplifier applied to the feedback loop; the other is a post-amplifier gain module, the input of which is electrically connected to the output of the open-loop amplifier applied to the feedback loop; wherein the product of the gain coefficients of the two gain modules is the reciprocal of the target amplification coefficient of the open-loop amplifier applied to the feedback loop. The comparator has its first input terminal electrically connected to the input terminal of the preceding gain module, its second input terminal electrically connected to the output terminal of the following gain module, and its output signal electrically connected as a bias signal to the bias signal input terminals of the open-loop amplifier used in the successive approximation analog-to-digital converter and the open-loop amplifier used in the feedback loop.
[0010] Optionally, the feedback network further includes: A loop filter module is provided, wherein the input terminal of the loop filter module is electrically connected to the output terminal of the comparator, and the output signal of the loop filter module is electrically connected as a bias signal to the bias signal input terminals of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop.
[0011] Optionally, when the gain module is located after the open-loop amplifier applied to the feedback loop, the input terminal of the open-loop amplifier applied to the feedback loop is electrically connected to a reference voltage source; or, when the gain module is located before the open-loop amplifier applied to the feedback loop, the input terminal of the gain module is electrically connected to a reference voltage source; or, when there are two gain modules, the input terminal of the preceding gain module is electrically connected to a reference voltage source. The reference voltage output by the reference voltage source is a voltage greater than 0 or less than 0.
[0012] Optionally, it also includes: The switching module includes a first switching switch and a second switching switch. The first switching switch is used to switch the input signals of the two open-loop amplifiers to each other, and the second switching switch is used to switch the output signals of the two open-loop amplifiers to each other, so as to switch the operating states of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop.
[0013] Optionally, the first switching switch is used to switch the input signals of the two open-loop amplifiers to each other at preset time intervals; The second switching switch is used to operate synchronously with the first switching switch to switch the output signals of the two open-loop amplifiers to each other.
[0014] Optionally, the two open-loop amplifiers have a consistent layout, and the devices in the two open-loop amplifiers are arranged in a cross pattern according to device type to achieve common centroid matching between the two open-loop amplifiers.
[0015] Optionally, virtual device units are arranged around the outside of the two open-loop amplifiers.
[0016] Optionally, the two open-loop amplifiers are fabricated using the same fabrication process.
[0017] Secondly, the present invention also provides a gain-stable open-loop amplifier, characterized in that it comprises: An amplifier circuit comprising two open-loop amplifiers; wherein the two open-loop amplifiers are disposed in the same region of the same chip and share a power network; Two feedback networks, each corresponding to one of the open-loop amplifier circuits; Each open-loop amplifier has a switching switch at its input terminal and a switching switch at its output terminal. The switching switches are used to switch one of the two open-loop amplifiers to a state where it is applied in a successive approximation analog-to-digital converter and disconnected from the corresponding feedback network at preset intervals; and to switch the other of the two open-loop amplifiers to a state where it is electrically connected to the corresponding feedback network and disconnected from the other circuits in the successive approximation analog-to-digital converter except for the open-loop amplifier.
[0018] In the technical solution provided by this invention, two open-loop amplifiers are placed in the same area of the same chip and share a power network. The open-loop amplifier configured for a successive approximation analog-to-digital converter (ADC) is applied to the ADC, and the open-loop amplifier configured for the feedback loop is electrically connected to the feedback network. In this configuration, the open-loop amplifier configured for the feedback loop can adjust its gain coefficient in real time through the feedback network. Since the two amplifiers share environmental parameters such as process-power-voltage-temperature (PVT), when the gain coefficient of the open-loop amplifier configured for the feedback loop is adjusted, the gain coefficient of the open-loop amplifier configured for the successive approximation ADC can also be adjusted, thereby ensuring the stability of the gain coefficient of the open-loop amplifier applied to the successive approximation ADC. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of a gain-stable open-loop amplifier according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a gain-stable open-loop amplifier according to another embodiment of the present invention; Figure 3 This is a schematic diagram of a gain-stable open-loop amplifier according to another embodiment of the present invention; Figure 4 This is a schematic diagram of a gain-stable open-loop amplifier according to another embodiment of the present invention; Figure 5 This is a schematic diagram of a gain-stable open-loop amplifier according to another embodiment of the present invention. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0021] This invention provides a gain-stable open-loop amplifier, such as... Figure 1 As shown, it includes: An amplifier circuit comprising two open-loop amplifiers; one open-loop amplifier is used in a successive approximation analog-to-digital converter; the other open-loop amplifier is configured for a feedback loop; wherein the two open-loop amplifiers are configured in the same region of the same chip, and the two open-loop amplifiers share a power network and a bias signal; In some embodiments, one open-loop amplifier in the amplifier circuit can be applied to a successive approximation analog-to-digital converter (ADC), and the other open-loop amplifier is applied to the feedback loop. Since the two open-loop amplifiers are located in the same area of the same chip and share a power network and bias signal, their environmental parameters, such as process-supply voltage-temperature (PVT), are highly consistent. In this case, when the gain coefficient of the open-loop amplifier applied to the feedback loop is adjusted, the gain coefficient of the open-loop amplifier applied to the successive approximation ADC is adjusted synchronously because the two open-loop amplifiers share the bias signal. In some preferred embodiments, the open-loop amplifier can be, for example, a transimpedance amplifier. Those skilled in the art will understand that in this embodiment, both open-loop amplifiers in the amplifier circuit are arranged as open-loop amplifiers; however, the open-loop amplifier applied to the feedback loop is fed back by an additional feedback loop, resulting in closed-loop feedback for the open-loop amplifier.
[0022] A feedback network is provided, wherein the input terminal of the feedback network is electrically connected to the output terminal of the open-loop amplifier applied to the feedback loop, and the output terminal of the feedback network is electrically connected to the bias signal input terminals of the two open-loop amplifiers, so as to realize closed-loop feedback of the open-loop amplifier applied to the feedback loop.
[0023] In some embodiments, the feedback network detects gain fluctuations in the open-loop amplifier applied to the feedback loop and outputs a bias signal based on these gain fluctuations, thereby synchronously adjusting the gain coefficients of the two open-loop amplifiers.
[0024] In the technical solution provided by this invention, two open-loop amplifiers are placed in the same area of the same chip and share a power network and bias signal. The open-loop amplifier configured for a successive approximation analog-to-digital converter (ADC) is applied to the ADC, and the open-loop amplifier configured for the feedback loop is electrically connected to the feedback network. In this configuration, the open-loop amplifier configured for the feedback loop can adjust its gain coefficient in real time through the feedback network. Since the two amplifiers share environmental parameters such as process voltage-temperature (PVT), when the gain coefficient of the open-loop amplifier configured for the feedback loop is adjusted, the gain coefficient of the open-loop amplifier configured for the successive approximation ADC can also be adjusted, thereby ensuring the stability of the gain coefficient of the open-loop amplifier applied to the successive approximation ADC.
[0025] As an optional implementation, continue as follows Figure 1 As shown, the input terminal of the open-loop amplifier used in the successive approximation analog-to-digital converter is electrically connected to the preceding successive approximation register module, and the output terminal of the open-loop amplifier used in the successive approximation analog-to-digital converter is electrically connected to the following successive approximation register module.
[0026] In some embodiments, open-loop amplifiers are typically used in successive approximation analog-to-digital converters. Therefore, in this embodiment, a preferred embodiment is provided in which the input terminal of the open-loop amplifier used in the successive approximation analog-to-digital converter is electrically connected to the preceding successive approximation register module, and the output terminal of the open-loop amplifier used in the successive approximation analog-to-digital converter is electrically connected to the following successive approximation register module, thereby forming a successive approximation analog-to-digital converter.
[0027] As an optional implementation, continue as follows Figure 1 As shown, the feedback network includes: A gain module, wherein the input terminal of the gain module is electrically connected to the output terminal of the open-loop amplifier applied to the feedback loop, wherein the gain coefficient of the gain module is the reciprocal of the target amplification coefficient of the open-loop amplifier applied to the feedback loop; In some embodiments, the input of the open-loop amplifier applied to the feedback loop is the original reference voltage. Since the gain coefficient of the gain module is the reciprocal of the target gain coefficient of the open-loop amplifier applied to the feedback loop, if the open-loop amplifier applied to the feedback loop operates at the target gain coefficient, the signal output from the gain module will be restored to the reference voltage. If the gain coefficient of the open-loop amplifier applied to the feedback loop deviates from the target gain coefficient, the signal output from the gain module will deviate from the reference voltage. By comparing the reference voltage at the input of the open-loop amplifier applied to the feedback loop with the signal at the output of the gain module, it can be determined whether the gain coefficient of the open-loop amplifier applied to the feedback loop has fluctuated.
[0028] The comparator has a first input terminal electrically connected to the input terminal of the open-loop amplifier applied to the feedback loop, a second input terminal electrically connected to the output terminal of the gain module, and an output signal of the comparator serving as a bias signal electrically connected to the bias signal input terminals of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop.
[0029] In some embodiments, the comparator compares the signal at its first input terminal with the signal at the input terminal of the open-loop amplifier applied to the feedback loop with the signal output by the gain module. The output result can characterize the fluctuation state of the open-loop amplifier applied to the feedback loop. Furthermore, by using the output signal of the comparator as a bias signal and comparing it with the bias signals of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop, real-time adjustment can be achieved.
[0030] As an optional implementation method, such as Figure 2 As shown, the feedback network includes: A gain module, the output of which is electrically connected to the input of the open-loop amplifier applied to the feedback loop, wherein the gain coefficient of the gain module is the reciprocal of the target amplification coefficient of the open-loop amplifier applied to the feedback loop; The comparator has its first input terminal electrically connected to the input terminal of the gain module, its second input terminal electrically connected to the output terminal of the open-loop amplifier applied to the feedback loop, and its output signal, as a bias signal, electrically connected to the bias signal input terminals of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop.
[0031] In some embodiments, similar to the previous embodiment, in this embodiment, the gain module is placed before the open-loop amplifier applied to the feedback loop. The reference voltage is first reduced and then amplified by the open-loop amplifier. The signal output by the open-loop amplifier is then compared with the reference voltage to determine the fluctuation status of the open-loop amplifier. Furthermore, the output signal of the comparator is used as a bias signal and compared with the bias signals of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop to achieve real-time adjustment.
[0032] As an optional implementation method, such as Figure 3 As shown, the feedback network includes: Two gain modules are provided, one of which is a pre-amplifier gain module, the output of which is electrically connected to the input of the open-loop amplifier applied to the feedback loop; the other is a post-amplifier gain module, the input of which is electrically connected to the output of the open-loop amplifier applied to the feedback loop; wherein the product of the gain coefficients of the two gain modules is the reciprocal of the target amplification coefficient of the open-loop amplifier applied to the feedback loop. The comparator has its first input terminal electrically connected to the input terminal of the preceding gain module, its second input terminal electrically connected to the output terminal of the following gain module, and its output signal electrically connected as a bias signal to the bias signal input terminals of the open-loop amplifier used in the successive approximation analog-to-digital converter and the open-loop amplifier used in the feedback loop.
[0033] In some embodiments, similar to the previous two embodiments, in this embodiment, two gain modules are respectively positioned before and after the open-loop amplifier applied to the feedback loop. The product of the gain coefficients of the two gain modules is the reciprocal of the target amplification factor of the open-loop amplifier. The two gain modules together reduce the signal, while the open-loop amplifier amplifies the signal. The signal output from the subsequent gain module is then compared with a reference voltage to determine the fluctuation status of the open-loop amplifier. Furthermore, the output signal of the comparator is used as a bias signal, and real-time adjustment can be achieved by comparing it with the bias signals of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop. In some embodiments, the method of adjusting the bias of the open-loop amplifier using the bias signal can be implemented using any existing technology, which will not be elaborated here.
[0034] As an optional implementation, the feedback network further includes: When the gain module is placed after the open-loop amplifier applied to the feedback loop, the input of the open-loop amplifier applied to the feedback loop is electrically connected to a reference voltage source; or, when the gain module is placed before the open-loop amplifier applied to the feedback loop, the input of the gain module is electrically connected to a reference voltage source; or, when there are two gain modules, the input of the preceding gain module is electrically connected to a reference voltage source. The reference voltage output by the reference voltage source is a voltage greater than 0 or less than 0.
[0035] In some embodiments, since the control signal generated by the open-loop amplifier applied to the feedback loop during operation may contain noise, it needs to be properly filtered to avoid introducing noise into the open-loop amplifier path applied to the successive approximation analog-to-digital converter.
[0036] As an optional implementation, the input terminal of the open-loop amplifier applied to the feedback loop is electrically connected to a reference voltage source, the reference voltage output by the reference voltage source being a voltage greater than 0 or less than 0.
[0037] In some embodiments, since the input signal at the input terminal of the open-loop amplifier applied to the feedback loop is amplified and then reduced back before it can be compared to see if it deviates from the reference voltage, the reference voltage cannot be 0. Otherwise, the change in the amplification factor of the open-loop amplifier cannot be characterized during the amplification and reduction process.
[0038] As an optional implementation method, such as Figure 4 As shown, it also includes: The switching module includes a first switching switch and a second switching switch. The first switching switch is used to switch the input signals of the two open-loop amplifiers to each other, and the second switching switch is used to switch the output signals of the two open-loop amplifiers to each other, so as to switch the operating states of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop.
[0039] In some embodiments, although the two open-loop amplifiers share multiple environmental parameters, there are still slight differences. In order to further improve the stability of the open-loop amplifiers applied to the successive approximation analog-to-digital converter, a switching module is used to switch the two open-loop amplifiers in this embodiment, so that the two open-loop amplifiers are alternately applied to the successive approximation analog-to-digital converter and applied to the feedback loop, thereby further improving the stability of the amplification factor. Figure 4The diagram illustrates, by way of example, a first switching switch and a second switching switch when a single gain module is placed after an open-loop amplifier. Those skilled in the art should understand that in other cases described above, the first switching switch and the second switching switch can be arranged in the same way. That is, the first switching switch and the second switching switch are used to switch the input signals and output signals of the two open-loop amplifiers, respectively, so that the application paths of the two open-loop amplifiers can be switched between each other.
[0040] As an optional implementation, the first switching switch is used to switch the input signals of the two open-loop amplifiers to each other at preset time intervals; The second switching switch is used to operate synchronously with the first switching switch to switch the output signals of the two open-loop amplifiers to each other.
[0041] In some embodiments, the preset time can be determined, for example, based on prior data. For example, by measuring multiple times, the operating time at which the difference or ratio of the amplification factors of the two open-loop amplifiers produces an unacceptable difference can be determined, and the time shorter than this operating time can be set as the preset time.
[0042] As an optional implementation, the two open-loop amplifiers have a consistent layout, and the devices in the two open-loop amplifiers are arranged in a cross pattern according to device type to achieve common centroid matching between the two open-loop amplifiers.
[0043] In some embodiments, to avoid differences in the effects of the two open-loop amplifiers due to the concentration gradient on the wafer, the devices in the two open-loop amplifiers are arranged in a cross-arrangement. For example, the multiple MOS transistors of the two amplifiers are arranged in an alternating manner, i.e., arranged in the manner of ABAB..., where A represents a device of one open-loop amplifier and B represents a device of the other open-loop amplifier.
[0044] As an alternative implementation, virtual device units are arranged around the outside of the two open-loop amplifiers.
[0045] In some embodiments, by surrounding the two open-loop amplifiers with virtual devices, multiple devices of the two open-loop amplifiers have the same etching conditions, whether they are in the center or at the edge, thus avoiding differences between the two open-loop amplifiers due to differences in etching conditions.
[0046] As an alternative implementation, both open-loop amplifiers are fabricated using the same fabrication process.
[0047] In some embodiments, by fabricating two open-loop amplifiers using the same fabrication process, performance differences between the two open-loop amplifiers due to differences in fabrication processes can be avoided.
[0048] This invention also provides a gain-stable open-loop amplifier, such as... Figure 5 As shown, it includes: An amplifier circuit comprising two open-loop amplifiers; wherein the two open-loop amplifiers are disposed in the same region of the same chip and share a power network; Two feedback networks, each corresponding to one of the open-loop amplifier circuits; Each open-loop amplifier has a switching switch at its input terminal and a switching switch at its output terminal. The switching switches are used to switch one of the two open-loop amplifiers to a state where it is applied in a successive approximation analog-to-digital converter and disconnected from the corresponding feedback network at preset intervals; and to switch the other of the two open-loop amplifiers to a state where it is electrically connected to the corresponding feedback network and disconnected from the other circuits in the successive approximation analog-to-digital converter except for the open-loop amplifier.
[0049] In some embodiments, each of the two feedback networks can be the same as the feedback network in any of the foregoing embodiments, that is, it can adopt a method such as... Figure 1-3 Any one of the aforementioned feedback networks. Those skilled in the art should understand that, when using any of the aforementioned feedback networks, the gain coefficient of the gain module should be the reciprocal of the amplification factor of the corresponding open-loop amplifier, or the product of the gain coefficients of the preceding and following gain modules should be the reciprocal of the amplification factor of the corresponding open-loop amplifier. The four switching switches should operate synchronously. That is, when one open-loop amplifier is used in a successive approximation analog-to-digital converter, another open-loop amplifier should be synchronously connected to its corresponding feedback network.
[0050] In this embodiment, based on the situation where there are still slight differences between open-loop amplifiers in the same region of the same chip, two open-loop amplifiers are set up and corresponding feedback networks are set up respectively. The two open-loop amplifiers are applied to the successive approximation analog-to-digital converter in turn. When either open-loop amplifier is not applied to the successive approximation analog-to-digital converter, it is connected to the feedback network to adjust its amplification factor in a closed loop. Thus, when it is applied to the successive approximation analog-to-digital converter again, it can amplify the signal with the target amplification factor.
[0051] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A gain-stable open-loop amplifier, characterized in that, include: An amplifier circuit comprising two open-loop amplifiers; one open-loop amplifier being used in a successive approximation analog-to-digital converter; and the other open-loop amplifier being used in a feedback loop; wherein the two open-loop amplifiers are located in the same region of the same chip, and the two open-loop amplifiers share a power network and a bias signal; A feedback network is provided, wherein the input terminal of the feedback network is electrically connected to the output terminal of the open-loop amplifier applied to the feedback loop, and the output terminal of the feedback network is electrically connected to the bias signal input terminals of the two open-loop amplifiers, so as to realize closed-loop feedback of the open-loop amplifier applied to the feedback loop.
2. The gain-stable open-loop amplifier according to claim 1, characterized in that, The input terminal of the open-loop amplifier used in the successive approximation analog-to-digital converter is electrically connected to the preceding successive approximation register module, and the output terminal of the open-loop amplifier used in the successive approximation analog-to-digital converter is electrically connected to the following successive approximation register module.
3. The gain-stable open-loop amplifier according to claim 1, characterized in that, The feedback network includes: A gain module, wherein the input terminal of the gain module is electrically connected to the output terminal of the open-loop amplifier applied to the feedback loop, wherein the gain coefficient of the gain module is the reciprocal of the target amplification coefficient of the open-loop amplifier applied to the feedback loop; The comparator has a first input terminal electrically connected to the input terminal of the open-loop amplifier applied to the feedback loop, a second input terminal electrically connected to the output terminal of the gain module, and an output signal of the comparator serving as a bias signal electrically connected to the bias signal input terminals of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop.
4. The gain-stable open-loop amplifier according to claim 1, characterized in that, The feedback network includes: A gain module, the output of which is electrically connected to the input of the open-loop amplifier applied to the feedback loop, wherein the gain coefficient of the gain module is the reciprocal of the target amplification coefficient of the open-loop amplifier applied to the feedback loop; The comparator has its first input terminal electrically connected to the input terminal of the gain module, its second input terminal electrically connected to the output terminal of the open-loop amplifier applied to the feedback loop, and its output signal, as a bias signal, electrically connected to the bias signal input terminals of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop.
5. The gain-stable open-loop amplifier according to claim 1, characterized in that, The feedback network includes: Two gain modules are provided, one of which is a pre-amplifier gain module, the output of which is electrically connected to the input of the open-loop amplifier applied to the feedback loop; the other is a post-amplifier gain module, the input of which is electrically connected to the output of the open-loop amplifier applied to the feedback loop; wherein the product of the gain coefficients of the two gain modules is the reciprocal of the target amplification coefficient of the open-loop amplifier applied to the feedback loop. The comparator has its first input terminal electrically connected to the input terminal of the preceding gain module, its second input terminal electrically connected to the output terminal of the following gain module, and its output signal electrically connected as a bias signal to the bias signal input terminals of the open-loop amplifier used in the successive approximation analog-to-digital converter and the open-loop amplifier used in the feedback loop.
6. The gain-stable open-loop amplifier according to any one of claims 3-5, characterized in that, The feedback network also includes: A loop filter module is provided, wherein the input terminal of the loop filter module is electrically connected to the output terminal of the comparator, and the output signal of the loop filter module is electrically connected as a bias signal to the bias signal input terminals of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop.
7. The gain-stable open-loop amplifier according to claim 6, characterized in that, Also includes: The switching module includes a first switching switch and a second switching switch. The first switching switch is used to switch the input signals of the two open-loop amplifiers to each other, and the second switching switch is used to switch the output signals of the two open-loop amplifiers to each other, so as to switch the operating states of the open-loop amplifier applied to the successive approximation analog-to-digital converter and the open-loop amplifier applied to the feedback loop.
8. The gain-stable open-loop amplifier according to claim 7, characterized in that, The first switching switch is used to switch the input signals of the two open-loop amplifiers to each other at preset time intervals; The second switching switch is used to operate synchronously with the first switching switch to switch the output signals of the two open-loop amplifiers to each other.
9. The gain-stable open-loop amplifier according to claim 1, characterized in that, The two open-loop amplifiers have a consistent layout, and the devices in the two open-loop amplifiers are arranged in a cross pattern according to device type to achieve common centroid matching between the two open-loop amplifiers.
10. A gain-stable open-loop amplifier, characterized in that, include: An amplifier circuit comprising two open-loop amplifiers; wherein the two open-loop amplifiers are disposed in the same region of the same chip and share a power network; Two feedback networks, each corresponding to one of the open-loop amplifier circuits; Each open-loop amplifier has a switching switch at its input terminal and a switching switch at its output terminal. The switching switches are used to switch one of the two open-loop amplifiers to a state where it is applied in a successive approximation analog-to-digital converter and disconnected from the corresponding feedback network at preset intervals; and to switch the other of the two open-loop amplifiers to a state where it is electrically connected to the corresponding feedback network and disconnected from the other circuits in the successive approximation analog-to-digital converter except for the open-loop amplifier.