CIRCUIT CALIBRATING METHOD AND CIRCUIT CALIBRATING SYSTEM |
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申请号 | US14753036 | 申请日 | 2015-06-29 | 公开(公告)号 | US20160173116A1 | 公开(公告)日 | 2016-06-16 |
申请人 | PixArt Imaging Inc.; | 发明人 | Hsiang-Wei Hwang; Yung-Hung Chen; Han-Chi Liu; | ||||
摘要 | A circuit calibrating method, applied to an ACS generating circuit, which comprises a plurality of ACS generating units and activates the ACS generating unit corresponding to different DCCs to generate difference ACSs. The circuit calibrating method comprises: (a) determining which one of the ACSs has a large difference from an ideal value thereof; (b) adjusting a number of the ACS generating units, which are activated by a DCC corresponding to the ACS acquired in the step (a), or a next stage of the DCC corresponding to the ACS acquired in the step (a); and (c) generating the ACS to a target circuit, according to the number of the ACS generating circuits adjusted in the step (b). | ||||||
权利要求 | What is claimed is: |
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说明书全文 | 1. Field of the Invention The present invention relates to a circuit calibrating method and a circuit calibrating system, and particularly relates to a circuit calibrating method and a circuit calibrating system which can control the number of active analog control signal generating units to reduce signal drift. 2. Description of the Prior Art Some drift may occur during the manufacturing process for a circuit, such that all characteristics (ex. current, voltage, capacitance, and resistance) may have undesired values. Accordingly, a calibrating mechanism is needed. In this embodiment, the digital control code is a 3 bit code, and the ACS generating circuit comprises 7 ACS generating units with an ACS generating unit U1, 2 ACS generating units U2, and 4 ACS generating units U4. As depicted in For more detail, each ACS generating unit may have a signal draft amount which has a signal drift with a standard deviation δcell, thus the signal drift is more serious if more differently activated ACS generating units are activated for each time. For example, if the ACS signal generating units are respectively activated by the digital control code 011 and 010, only one differently activated ACS generating unit U1 exists, thus the analog control signals ACS generated due to the digital control code 011 and 010 may exist a signal draft amount which has a signal drift with a standard deviation δcell. Following the same rule, if the ACS signal generating units are respectively activated by the digital control code 001 and 010, three differently activated ACS generating units U1, U2 exist, thus the analog control signals ACS generated due to the digital control code 001 and 010 may exist a signal draft amount which has a signal drift with a standard deviation √{square root over (3)}δcell. Following the same rule, if the ACS signal generating units are respectively activated by the digital control code 011 and 100, seven differently activated ACS generating units exist (all U1, U2 and U4), thus the analog control signals ACS generated due to the digital control code 011 and 100 may exist a signal draft amount which has an signal drift with a standard deviation √{square root over (7)}δcell. Accordingly, one objective of the present application is to provide a circuit calibrating method that can reduce signal drift and increase a tolerance range. Another objective of the present application is to provide a circuit calibrating system that can reduce signal drift and increase a tolerance range. One embodiment of the present invention discloses a circuit calibrating method, for calibrating a target circuit, applied to an analog control signal generating circuit comprising a plurality of analog control signal generating units, wherein the analog control signal generating circuit correspondingly activates at least one part of the analog control signal generating units to generate different analog control signals according to different digital control codes. The circuit calibrating method comprises: (a) determining which one of the analog control signals has a large difference between an actual value of the analog control signal and an ideal value of the analog control signal; (b) adjusting a number of the analog control signal generating units that a digital control code corresponding to the analog control signal acquired in the step (a) can activate, or adjusting a number of the analog control signal generating units that a neighboring stage for the digital control code corresponding to the analog control signal acquired in the step (a) can activate; and (c)generating the analog control signal to the target circuit, according to the number of the analog control signal generating units, which is adjusted in the step (b). Another embodiment of the present application discloses a circuit calibrating system applied to calibrate a target circuit. The circuit calibrating system comprises: a digital control code generating circuit, configured to generate a digital control code; an analog control signal generating circuit, comprising a plurality of analog control signal generating units, configured to correspondingly activate at least one part of the analog control signal generating units to generate different analog control signals according to different digital control codes; a control unit, configured to perform following steps (a)-(c): (a) determining which one of the analog control signals has a large difference between an actual value of the analog control signal and an ideal value of the analog control signal; (b) adjusting a number of the analog control signal generating units that a digital control code corresponding to the analog control signal acquired in the step (a) can activate, or adjusting a number of the analog control signal generating units that a neighboring stage for the digital control code corresponding to the analog control signal acquired in the step (a) can activate; and (c) generating the analog control signal to the target circuit, according to the number of the analog control signal generating units, which is adjusted in the step (b). In view of above-mentioned embodiments, the signal drift for the analog control signal can be effectively reduced, to avoid that the signal drift is over a tolerance range. Please note, besides the advantage of decreasing the signal drift, the present invention can further provide an advantage of “increasing the tolerance range for the signal drift. These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. Some embodiments are provided in following descriptions to solve the issue for prior art: A specific stage of digital control code or some stages of digital control codes make corresponding analog control signal(s) generates larger signal drift. More detail examples are provided in following descriptions to explain the concept of the present application. Please note the embodiment in In one embodiment, the adjusting number of the ACS generating units activated by one bit value for a specific stage of digital control code can be applied to other stages of digital control codes. For example, the ACS generating units activated by the digital control code 100 are adjusted from four U4 to three U4, that is, a number of the ACS generating units activated by the bit value corresponding to the third bit of the digital control code 100 is adjusted from four to three. Thereby, the digital control code 111, which is initially supposed to activate one ACS generating unit U1, two ACS generating units U2 and four ACS generating units U4, will be adjusted to activate one ACS generating unit U1, two ACS generating units U2 and three ACS generating units U4, due to the adjustment for the number of ACS generating units activated by the digital control code 100. However, each stage of digital control code can be independent and does not affect each other. Following examples depict how to determine a number of activated ACS generating units of which digital control code should be adjusted. In one embodiment, it is determined by the following Equation (1): 1.5×√{square root over (M)}δcell<Serr−0.5LSB Equation (1) M indicates a number for differently activated ACS generating units if a specific stage of digital control code is switched to another stage of digital control code. Take LSB is a quantization error for the ACS generating circuit itself, ideally it is zero. Accordingly, based upon above-mentioned Equation (1), M must be smaller than For example, if the analog control signal is a current and Serr is 0.75 mA and the quantization error for the ACS generating circuit is 1 mA, M must be smaller than If M, which is the number for differently activated ACS generating units if a specific stage of digital control code is switched to another stage of digital control code, at least one for activated ACS generating units for these two digital control codes should be adjusted. In another embodiment, following equation (2) can be applied to determine a number of activated ACS generating units: 1.5×√{square root over (M)}δcell<Serr+NLSB−0.5LSB Equation (2) N is a number for activated ACS generating units to be adjusted, thus if M, δcell, Serr and LSB are already known, the number for activated ACS generating units to be adjusted can be acquired. As above-mentioned, the ACS generating units activated by the digital control code is not limited to be adjusted for one time, and is not limited to adjust one ACS generating unit. Please note, the scope of the present invention is not limited to above-mentioned embodiments. Accordingly, one circuit calibrating method provided by the present invention can be summarized as: A circuit calibrating method, for calibrating a target circuit, applied to an ACS generating circuit comprising a plurality of ACS generating units, wherein the ACS generating circuit correspondingly activates at least one part of the ACS generating units to generate different analog control signals according to different digital control codes, wherein the circuit calibrating method comprises: (a) determining which one of the analog control signals has a large difference between an actual value of the analog control signal and an ideal value of the analog control signal (for example, in Further, such embodiment can further comprise: controlling the analog control signal generating units to receive a third digital control code, to activate a third number of the analog control signal generating units among the analog control signal generating units, to generate a third analog control signal to the target circuit; and if a maximum possible signal drift for differently activated analog control signal generating units between the second number of the analog control signal generating units and the third number of the analog control signal generating units is larger than a second threshold error, adjust a number for the analog control signal generating units activated by the third digital control code (ex. embodiments for Another embodiment further comprises: either the step of adjusting the number of the analog control signal generating units activated by the first digital control code or the step of adjusting the number of the analog control signal generating units activated by the second digital control code adjusts a number of the analog control signal generating units activated by a specific bit of the first digital control code and the second digital control code, wherein the circuit calibrating method further comprises: correspondingly adjusting the number of the analog control signal generating units activated by the specific bit of a third digital control code while the analog control signal generating units receive the third digital control code. For example, in the embodiment of Other operations for the circuit calibrating system 1100 has been described in other embodiments, thus are omitted for brevity here. In view of above-mentioned embodiments, the signal drift for the analog control signal can be effectively reduced, to avoid that the signal drift is over a tolerance range. Please note, besides the advantage of decreasing the signal drift, the present invention can further provide an advantage of “increasing the tolerance range for the signal drift. For a circuit calibrating system, if the signal drift is negative, it does not affect the system much, since the positive signal drift in following steps can neutralize the negative signal drift. However, if the signal drift is positive, the system calibrating error may accumulate, such that the system calibrating error may over the tolerance range while switching the digital control codes. Based upon above-mentioned mechanism, a negative signal drift is provided to a switch operation that may have a larger signal drift (i.e. decrease a number for the ACS generating units activated by the digital control code). By this way, the tolerance range for the system error calibrating mechanism can be extended in the positive direction. Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims. |