# US 8,571,837 B1 · System and method for simulating a bi-directional connect module within an analog and mixed-signal circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,571,837 B1 - Document ID: US8571837B1 - Status: Granted - Kind: B1 - Application number: 12/838,348 - Filed: 2010-07-16 - Granted: 2013-10-29 - Earliest claimed: 2010-07-16 - Assignees: Cadence Design Systems, Inc. - Applicants: Junwei Hou - Inventors: Junwei Hou - Web page: https://patentgrep.com/patent/US8571837B1 ## CPC - G06F 30/33: Design verification, e.g. functional simulation or model checking - G06F 30/367: Design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE], direct methods or relaxation methods - G06F 2117/08: HW-SW co-design, e.g. HW-SW partitioning - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract According to some embodiments, a method is provided for simulating an analog and mixed-signal circuit design comprising an analog circuit segment connected to a digital circuit segment at a connection point, the method comprising: inserting a bi-directional interface element at the connection point, wherein the analog circuit segment connects to an analog port of the bi-directional interface element and the digital circuit segment connects to a digital port of the bi-directional interface element; and operating the bi-directional interface element such that the bi-directional interface element detects a signal direction and, according to the signal direction, either converts a first analog signal received from the analog port to a first digital signal for the digital port while maintaining a first signal strength of the first analog signal, or converts a second digital signal received from the digital port to a second analog signal for the analog port while maintaining a second signal strength of the second digital signal. ## Claims ### Claim 1 A method for simulating an analog and mixed-signal circuit design comprising an analog circuit segment connected to a digital circuit segment at a connection point, the method comprising: using a computer system to insert a bi-directional interface element at the connection point, wherein the analog circuit segment connects to an analog port of the bi-directional interface element and the digital circuit segment connects to a digital port of the bi-directional interface element; and the bi-directional interface element detecting a signal direction and, according to the signal direction, either converting a first analog signal received from the analog port to a first digital signal for the digital port while maintaining a first signal strength of the first analog signal, or converting a second digital signal received from the digital port to a second analog signal for the analog port while maintaining a second signal strength of the second digital signal. ### Claim 2 (depends on 1) The method of claim 1, wherein if the bi-directional interface element is inserted at the connection point, the digital circuit segment is preserved as a single segment. ### Claim 3 (depends on 1) The method of claim 1, wherein the conversion of the first analog signal to the first digital signal comprises: determining an impedance of the analog circuit segment at the analog port; converting the first analog signal from a voltage value to a logic value, thereby resulting in the first digital signal; adjusting the first signal strength of the first digital signal according to the impedance of the analog circuit segment; and outputting the first digital signal through the digital port. ### Claim 4 (depends on 1) The method of claim 1, wherein the conversion of the second digital signal to the second analog signal comprises: determining the second signal strength of the second digital signal by resolving a signal strength of a digital driver of the digital circuit segment; converting the second digital signal from a logic value to a voltage value by resolving a signal value of the digital drive of the digital circuit segment; and outputting through the analog port the second analog voltage value and the second signal strength. ### Claim 5 (depends on 1) The method of claim 1, wherein the method is configured for Verilog-AMS, and the bi-directional interface element is an AMS bidir connect module. ### Claim 6 (depends on 1) The method of claim 1, wherein first signal strength is defined by a Verilog strength level for the digital port, and the second signal strength is defined by a Verilog strength level for the analog port. ### Claim 7 (depends on 1) The method of claim 1, wherein the analog circuit segment and the analog portion of the bi-directional interface element are simulated in a continuous time domain circuit simulator. ### Claim 8 (depends on 1) The method of claim 1, wherein the digital circuit segment and the digital portion of the bi-directional interface element are simulated in a discrete time domain circuit simulator. ### Claim 9 A computer program product for simulating an analog and mixed-signal circuit design comprising an analog circuit segment connected to a digital circuit segment at a connection point, the computer program product comprising a computer-readable storage medium having computer-readable program code embodied in said medium, the computer-readable program comprising: inserting a bi-directional interface element at the connection point, wherein the analog circuit segment connects to an analog port of the bi-directional interface element and the digital circuit segment connects to a digital port of the bi-directional interface element; and the bi-directional interface element detecting a signal direction and, according to the signal direction either converting a first analog signal received from the analog port to a first digital signal for the digital port while maintaining a first signal strength of the first analog signal, or converting a second digital signal received from the digital port to a second analog signal for the analog port while maintaining a second signal strength of the second digital signal. ### Claim 10 (depends on 9) The computer program product of claim 9, wherein if the bi-directional interface element is inserted at the connection point, the digital circuit segment is preserved as a single segment. ### Claim 11 (depends on 9) The computer program product of claim 9, wherein the conversion of the first analog signal to the first digital signal comprises: determining an impedance of the analog circuit segment at the analog port; converting the first analog signal from a voltage value to a logic value, thereby resulting in the first digital signal; adjusting the first signal strength of the first digital signal according to the impedance of the analog circuit element; and outputting the first digital signal through the digital port. ### Claim 12 (depends on 9) The computer program product of claim 9, wherein the conversion of the second digital signal to the second analog signal comprises: determining the second signal strength of the second digital signal by resolving a signal strength of a digital driver of the digital circuit segment; converting the second digital signal from a logic value to a voltage value by resolving a signal value of the digital drive of the digital circuit segment; and outputting through the analog port the second analog signal according to the voltage value and the second signal strength. ### Claim 13 (depends on 9) The computer program product of claim 9, wherein the method is configured for Verilog-AMS, and the bi-directional interface element is an AMS bidir connect module. ### Claim 14 (depends on 9) The computer program product of claim 9, wherein the first signal strength is defined by a Verilog strength level for the digital port, and the second signal strength is defined by a Verilog strength level for the analog port. ### Claim 15 (depends on 9) The computer program product of claim 9, wherein the analog circuit segment and the analog portion of the bi-directional interface element are simulated in a continuous time domain circuit simulator. ### Claim 16 (depends on 9) The computer program product of claim 9, wherein the digital circuit segment and the digital portion of the bi-directional interface element are simulated in a discrete time domain circuit simulator. ### Claim 17 A computer system configured to simulate an analog and mixed-signal circuit design comprising an analog circuit segment connected to a digital circuit segment at a connection point, comprising: a processor; a memory connected to the processor; and a computer readable medium having instructions embedded therein, the instructions configured to cause the processor to perform the operations of: inserting a bi-directional interface element at the connection point, wherein the analog circuit segment connects to an analog port of the bi-directional interface element and the digital circuit segment connects to a digital port of the bi-directional interface element; and the bi-directional interface element detecting a signal direction and, according to the signal direction, either converting a first analog signal received from the analog port to a first digital signal for the digital port while maintaining a first signal strength of the first analog signal, or converting a second digital signal received from the digital port to a second analog signal for the analog port while maintaining a second signal strength of the second digital signal. ### Claim 18 (depends on 17) The computer system of claim 17, wherein if the bi-directional interface element is inserted at the connection point, the digital circuit segment is preserved as a single segment. ### Claim 19 (depends on 17) The computer system of claim 17, wherein the conversion of the first analog signal to the first digital signal comprises: determining an impedance of the analog circuit segment at the analog port; converting the first analog signal from a voltage value to a logic value, thereby resulting in the first digital signal; adjusting the first signal strength of the first digital signal according to the impedance of the analog circuit segment; and outputting the first digital signal through the digital port. ### Claim 20 (depends on 17) The computer system of claim 17, wherein the conversion of the second digital signal to the second analog signal comprises: determining the second signal strength of the second digital signal by resolving a signal strength of a digital driver of the digital circuit segment; converting the second digital signal from a logic value to a voltage value by resolving a signal value of the digital drive of the digital circuit segment; and outputting through the analog port the second analog signal according to the voltage value and the second signal strength.