# US 12,009,834 B2 · Control circuit and method for calibrating signal converter, and signal conversion system using the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,009,834 B2 - Document ID: US12009834B2 - Status: Granted - Kind: B2 - Application number: 17/687,858 - Filed: 2022-03-07 - Published: 2023-02-02 - Granted: 2024-06-11 - Earliest claimed: 2021-07-29 - Assignees: Nuvoton Technology Corporation - Applicants: Nuvoton Technology Corporation - Inventors: Yun Kai Lai - Web page: https://patentgrep.com/patent/US12009834B2 ## CPC - H03M 1/76: using switching tree - H03M 1/0626: {by filtering} - H03M 1/08: of noise {(H03M1/0617 takes precedence)} - H03M 1/1023: {Offset correction (H03M1/1019 takes precedence; removal of offset already present on the analogue input signal H03M1/1295)} - H03M 1/368: {having a single comparator per bit, e.g. of the folding type} - H03M 1/66: Digital/analogue converters ({H03M1/001 – } H03M1/10 take precedence) - H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C) ## Abstract A control circuit and a method of calibrating a signal converter (such as DAC) are disclosed. The control circuit can be an existing control circuit, so no additional calibration circuit is required and the circuit area can be reduced. The control circuit can be an embedded microcontroller or other type of microcontroller. In general, the microcontroller includes an analog comparator and an arithmetic unit. With the combination of using the arithmetic unit to execute firmware program codes and using of the analog comparator, the control circuit is able to calibrate the signal converter. ## Claims ### Claim 1 A control circuit for calibrating a signal converter, comprising, a switch, wherein an input terminal of the switch is electrically connected to an output terminal of the signal converter and configured to receive an analog signal, which is outputted by the signal converter by converting a digital signal, an output terminal of the switch is selectively conducted to the input terminal based on an event trigger signal, and an initial value of the digital signal corresponds to an analog reference signal; an analog comparator, wherein a first input terminal of the analog comparator receives the analog reference signal, and a second input terminal of the analog comparator is electrically connected to an output terminal of the switch; a signal converter control unit electrically connected to an output terminal of the analog comparator and an input terminal of the signal converter, wherein the signal converter control unit is selectively enabled to transmit the digital signal to the input terminal of the signal converter based on the event trigger signal; wherein when the signal converter control unit determines that a comparison signal outputted from the analog comparator has no transition, the signal converter control unit increases or decreases a value of the digital signal based on an comparison signal, when the signal converter control unit determines that the comparison signal outputted from the analog comparator has transition, the signal converter control unit records the value of the digital signal after transition or before transition, so as to obtain an offset of the signal converter; and, a filter and control circuit electrically connected between the output terminal of the signal converter and the signal converter control unit, wherein based on an event trigger signal, the filter and control circuit is enabled based on an event trigger signal, to perform noise filtering on the comparison signal outputted from the analog comparator, and output the noise-filtered comparison signal to the signal converter control unit. ### Claim 2 (depends on 1) The control circuit according to claim 1, further comprising: a direct memory access electrically connected to the signal converter control unit; and a memory electrically connected to the direct memory access, wherein the memory stores the value of the digital signal; wherein the direct memory access is served as a data transmission bridge for the signal converter control unit to access the memory. ### Claim 3 (depends on 1) The control circuit according to claim 1, further comprising: an event trigger electrically connected to the switch and the signal converter control unit, wherein the event trigger detects whether a specific event occurs, to generate the event trigger signal; and a timer trigger electrically connected to the signal converter control unit, wherein the timer trigger is controlled by the signal converter control unit to enable the signal converter based on a timer trigger signal. ### Claim 4 (depends on 3) The control circuit according to claim 3, wherein the signal converter is an external digital to analog converter outside the control circuit, the control circuit is a single chip, and the control circuit comprises: a wrapper control circuit electrically connected to the signal converter control unit and the timer trigger, wherein the wrapper control circuit is enabled based on the timer trigger signal and configured to buffer and output the digital signal, and output the timer trigger signal; and a bus interface electrically connected to the wrapper control circuit and the external DAC, wherein the bus interface transmits the digital signal and the timer trigger signal to the external DAC. ### Claim 5 (depends on 3) The control circuit according to claim 3, wherein the control circuit is a single chip, and the control circuit comprises an internal DAC, the signal converter is the internal DAC, and the internal DAC is electrically connected to the timer trigger. ### Claim 6 (depends on 3) The control circuit according to claim 3, wherein the signal converter control unit is configured to set the specific event and a periodic trigger time of the timer trigger signal, and the signal converter control unit controls conduction between the input terminal of the switch and the output terminal. ### Claim 7 (depends on 1) The control circuit according to claim 1, further comprising: a reference signal supply unit electrically connected to the first input terminal of the analog comparator, wherein the reference signal supply unit provides the analog reference signal, and the analog reference signal is one of an internal reference voltage, an external reference voltage, and a bandgap voltage. ### Claim 8 (depends on 3) The control circuit according to claim 3, wherein the control circuit is an arithmetic circuit comprising the analog comparator, the arithmetic circuit executes a firmware program code to configure the switch, the signal converter control unit, the event trigger, and the timer trigger; or the switch, the signal converter control unit, the event trigger and the timer trigger are implemented by a plurality of hardware circuits. ### Claim 9 A signal conversion system, comprising: a signal converter; a control circuit calibrating the signal converter, and comprising: a switch, wherein an input terminal of the switch is electrically connected to an output terminal of the signal converter, the switch receives an analog signal, which is outputted by the signal converter by converting a digital signal, an output terminal and the input terminal of the switch are conducted to each other based on an event trigger signal, and an initial value of the digital signal corresponds to an analog reference signal; an analog comparator, wherein a first input terminal of the analog comparator receives the analog reference signal, and a second input terminal of the analog comparator is electrically connected to an output terminal of the switch; and a signal converter control unit electrically connected to an output terminal of the analog comparator and an input terminal of the signal converter, wherein the signal converter control unit is enabled to transmit the digital signal to the input terminal of the signal converter, based on an event trigger signal; wherein when the signal converter control unit determines that a comparison signal outputted from the analog comparator has no transition, the signal converter control unit increases or decreases a value of the digital signal based on a comparison signal, and when the signal converter control unit determines that the comparison signal outputted from the analog comparator has transition, the signal converter control unit records the value of the digital signal after transition or before transition, so as to obtain an offset of the signal converter; and, a filter and control circuit electrically connected between the output terminal of the signal converter and the signal converter control unit, wherein the filter and control circuit is enabled based on an event trigger signal to perform noise filtering on the comparison signal outputted from the analog comparator and output the noise-filtered comparison signal to the signal converter control unit. ### Claim 10 (depends on 9) The signal conversion system according to claim 9, wherein the control circuit comprises a direct memory access electrically connected to the signal converter control unit; and a memory electrically connected to the direct memory access, wherein the memory stores the value of the digital signal; wherein the direct memory access is served as a data transmission bridge for the signal converter control unit to access the memory. ### Claim 11 (depends on 9) The signal conversion system according to claim 9, wherein the control circuit comprises: an event trigger electrically connected to the switch and the signal converter control unit, wherein the event trigger detects whether a specific event occurs, so as to generate the event trigger signal; and a timer trigger electrically connected to the signal converter control unit, wherein the timer trigger is controlled by the signal converter control unit, to enable the signal converter based on a timer trigger signal. ### Claim 12 (depends on 11) The signal conversion system according to claim 11, wherein the signal converter is an external digital to analog converter outside the control circuit, the control circuit is a single chip, and the control circuit comprises: a wrapper control circuit electrically connected to the signal converter control unit and the timer trigger, wherein the wrapper control circuit is enabled based on a timer trigger signal to buffer and output the digital signal, and output the timer trigger signal; and a bus interface electrically connected to the wrapper control circuit and the external DAC, wherein the bus interface transmits the digital signal and the timer trigger signal to the external DAC. ### Claim 13 (depends on 11) The signal conversion system according to claim 11, wherein the control circuit is a single chip, and the control circuit comprises an internal DAC, the signal converter is the internal DAC, and the internal DAC is electrically connected to the timer trigger. ### Claim 14 (depends on 11) The signal conversion system according to claim 11, wherein the signal converter control unit is configured to set the specific event and a periodic trigger time of the timer trigger signal, and the signal converter control unit is configured to control conduction between the input terminal of the switch and the output terminal. ### Claim 15 (depends on 11) The signal conversion system according to claim 11, wherein the control circuit is an arithmetic circuit comprising the analog comparator, the arithmetic circuit executes a firmware program code to configure the switch, the signal converter control unit, the event trigger and the timer trigger; or the switch, the signal converter control unit, the event trigger and the timer trigger are implemented by a plurality of hardware circuits. ### Claim 16 (depends on 9) The signal conversion system according to claim 9, further comprising: digital data sources electrically connected to the signal converter and the control circuit; and an analog signal processing device electrically connected to the signal converter and the control circuit; wherein the analog signal processing device is a player device or a signal quality enhancement device previous to the player device. ### Claim 17 A method for calibrating a signal converter, wherein the method is executed in an arithmetic circuit in an automatic calibration mode, the arithmetic circuit comprises an analog comparator, and the method comprises: obtaining an initial value of the digital signal, wherein the signal converter converts the digital signal to generate the analog signal; obtaining the analog signal, outputted from the signal converter by converting the digital signal, and using the analog comparator to compare the analog signal with an analog reference signal, wherein an initial value of the digital signal corresponds to an analog reference signal; adjusting a value of the digital signal to update the digital signal, based on n comparison signal; outputting the updated digital signal to the signal converter; obtaining the comparison signal corresponding to the updated digital signal, to determine whether the comparison signal has a transition; when the comparison signal has no transition, continuously increasing or decreasing the value of the digital signal based on the comparison signal; and when the comparison signal has a transition, storing the digital signal of the comparison signal before the transition or after the transition, to obtain an offset of the signal converter; wherein a filter and control circuit are electrically connected between the output terminal of the signal converter and the signal converter control unit, the filter and control circuit are activated by an event trigger signal to conduct noise filtering on the comparison signal outputted from the analog comparator, and the noise-filtered comparison signal is then transmitted to the signal converter control unit. ### Claim 18 (depends on 17) The method for calibrating signal converter according to claim 17, further comprising: when an event trigger signal is enabled, obtaining the analog signal outputted by the signal converter, and outputting the updated digital signal to the signal converter, wherein when a specific event occurs, the event trigger signal is enabled, and the event trigger signal comprises at least one of a period event which is generated by periodically timing to a specific time, a forced-calibration event, and a temperature increasing/decreasing event.