JP5316657B2 - Semiconductor integrated circuit - Google Patents

Description

  The present invention relates to a semiconductor integrated circuit including both an A / D converter for taking in an analog signal from the outside and a D / A converter for outputting an analog signal to the outside.

  Conventionally, a digital-analog mixed LSI in which an analog module including an A / D converter and a D / A converter, such as a car navigation LSI (Large Scale Integration), is known.

In this kind of LSI, for inspecting the characteristics of the analog module, as shown in FIG. 8, the switch 118 and terminal Tdo or order to retrieve the digital signal converted by the A / D converter 110 to the outside, D / A A terminal Tdi and a switch 119 for supplying a digital signal from the outside to the input of the converter 111 are provided. Hereinafter, the terminals Tdo and Tdi are referred to as test terminals.

An LSI inspection apparatus is generally used for inspecting these analog modules.
Specifically, when inspecting the A / D converter 110, a high-precision analog signal is supplied from the LSI inspection apparatus 200 to the analog input terminal TI connected to the input of the A / D converter 110, and the A / D The conversion result (digital signal) in the converter 110 is taken into the LSI inspection apparatus 200 from the test terminal Tdo described above, and the quality of the operating characteristics of the A / D converter 110 is determined based on the taken-in conversion result.

  When the D / A converter 111 is inspected, the test pattern (digital signal) generated by the LSI inspection apparatus 200 is converted to D via the LSI test terminal Tdi, contrary to the case of the A / D converter 110. The signal is directly supplied to the input of the / A converter 111, and the conversion result (analog signal) in the D / A converter 111 is taken into the LSI inspection apparatus 200 from the analog output terminal TO connected to the output of the D / A converter 111. The quality of the operating characteristics of the D / A converter 111 is determined based on the acquired conversion result.

  Then, the LSI inspection apparatus 200 enables a test pattern generation circuit 201 and a D / A converter 202 for generating a test analog signal to be supplied to the analog input terminal TI of the LSI in order to enable the above-described inspection. A determination circuit 203 for determining an A / D conversion result acquired from the LSI test terminal Tdo, a test pattern generation circuit 204 for generating a test digital signal to be supplied to the LSI test terminal Tdi, and the LSI The D / A conversion result (analog signal) obtained from the analog output terminal TO is converted into a digital signal, and the A / D converter 205 and the determination circuit 206 for determining are very expensive.

That is, there is a problem in that the cost of inspecting the LSI is increased by using the expensive LSI inspection apparatus 200 in this way.
On the other hand, a device is proposed in which a test pattern generation circuit is provided in an LSI chip, and a D / A converter and an A / D converter are inspected using a test pattern generated by the test pattern generation circuit. (For example, refer to Patent Document 1).

JP 2001-134458 A

However, even in the apparatus described in Patent Document 1, the D / A conversion result is acquired by an external LSI inspection apparatus, and the LSI inspection apparatus determines whether the LSI is good or defective. such as the can not be, it was not able to sufficiently reduce the testing costs.

  And when adjusting the operating characteristics of the A / D converter and the D / A converter, such a high-cost LSI inspection apparatus must be used, and therefore the adjustment cost of the analog module cannot be reduced sufficiently. There was a problem.

In order to solve the above problem, an object of the present invention is to reduce the adjustment cost of an analog module in a semiconductor integrated circuit including an analog module including both an A / D converter and a D / A converter. .

2. The semiconductor integrated circuit according to claim 1, wherein the A / D converter converts an analog signal input via an analog input terminal into a digital signal, and is a signal processing unit. And a D / A converter converts a digital signal supplied from the signal processing unit into an analog signal and outputs the analog signal via an analog output terminal . However to, A / D converters and D / A converters, respectively, A / D adjustment parameters, by changing the adjustment parameters for the D / A, and is adjustably configure the operating characteristics.

  Further, the path setting means sets a loopback path that uses the output of the D / A converter as the input of the A / D converter at a preset adjustment timing. Then, the adjustment unit inputs a preset test pattern to the D / A converter, acquires a result pattern output from the A / D converter, and is specified from the result pattern. The A / D adjustment parameter and the D / A adjustment parameter are set so that the characteristics of the loopback system including the / D converter coincide with the preset target characteristics.

However, here, the characteristics of the loopback system do not need to precisely match the target characteristics, and may be matched within a preset allowable range.
The adjustment timing may be, for example, every fixed period, every time an adjustment command is input from the outside, or when the signal processing unit is not operating.

  According to the semiconductor integrated circuit of the present invention configured as described above, the operation characteristics of the A / D converter and the D / A converter are automatically adjusted at every adjustment timing, and it is necessary to use an expensive device for the adjustment. Therefore, the labor and cost required for adjustment can be greatly reduced.

  Further, according to the semiconductor integrated circuit of the present invention, by appropriately setting the adjustment timing, the operation characteristics of the A / D converter and the D / A converter due to LSI manufacturing variation, aging deterioration, temperature variation, power supply voltage variation, etc. Deterioration can be reliably prevented.

In the semiconductor integrated circuit of the present invention, among the A / D adjustment parameter and the D / A adjustment parameter, one is a first parameter, the other is a second parameter, the second parameter is fixed, and the first parameter is The first parameter adjustment means for repeatedly measuring the characteristics of the loopback system by changing and selecting the optimum value of the first parameter from the measurement result, and the first parameter to the optimum value selected by the first parameter adjustment means The second parameter adjusting means is configured to repeatedly measure the characteristics of the loopback system by fixing and changing the second parameter, and to select the optimum value of the second parameter from the measurement result .

  That is, the characteristic of the feedback system to be measured is a combination of the characteristics of the A / D converter and the characteristics of the D / A converter, but the operation of the first parameter adjusting means and the second parameter adjusting means as described above. Thus, both converters can be adjusted individually.

  Although the adjustment accuracy is improved by alternately repeating the operations of the first and second parameter adjusting means, it may not be possible to adjust the target characteristics even if the defective product is repeatedly executed. In such a case, it becomes impossible to finish the operation of both the partial adjusting means.

Therefore, as described in claim 2 , the adjusting means is configured to repeatedly execute the first parameter adjusting means and the second parameter adjusting means alternately within a preset upper limit number of times. It is desirable.
In the semiconductor integrated circuit of the present invention, the adjustment means adjusts a signal indicating whether or not the characteristic of the loopback system can be matched with the target characteristic as an adjustment result. You may be comprised so that it may output via an output terminal.
According to the semiconductor integrated circuit of the present invention configured as described above, the operation characteristics of the A / D converter and the D / A converter become desired target characteristics by monitoring the adjustment output terminal.
It is possible to identify whether or not the product is a good product or a defective product.

According to a fourth aspect of the present invention, there is provided a semiconductor integrated circuit comprising an adjustment parameter storage means for storing an A / D adjustment parameter and a D / A adjustment parameter set by the adjustment means. Good.

  In this case, when the power supply to the semiconductor integrated circuit is restarted after being stopped, the A / D converter and the D / A are controlled according to the A / D adjustment parameter and the D / A adjustment parameter stored in the adjustment parameter storage means. The converter can be operated immediately.

The block diagram which shows the structure of the principal part of the semiconductor integrated circuit of a 1st reference example . The flowchart for demonstrating operation | movement in a test control circuit. The block diagram which shows the structure of the principal part of the semiconductor integrated circuit of a 2nd reference example . 1 is a block diagram showing a configuration of a main part of a semiconductor integrated circuit according to a first embodiment . The flowchart which shows the content of the calibration process. The block diagram which shows the structure of the principal part of the semiconductor integrated circuit of 2nd Embodiment . The block diagram which shows the structure of the principal part of the semiconductor integrated circuit of 3rd Embodiment . The block diagram which shows the structure etc. of a conventional apparatus.

Embodiments of the present invention will be described below with reference to the drawings.
[First Reference Example]
<Configuration>
FIG. 1 is a block diagram showing a configuration of a main part of a semiconductor integrated circuit (LSI) 1 as a reference example of the present invention.

  As shown in FIG. 1, the semiconductor integrated circuit 1 inputs an analog input terminal TI for inputting an analog signal, an analog output terminal TO for outputting an analog signal, and a start command for starting a test operation described later. And a test result terminal TR for outputting the result of the test operation.

  The semiconductor integrated circuit 1 also realizes the functions required for the A / D converter 10 that converts an analog signal into a digital signal, the D / A converter 11 that converts a digital signal into an analog signal, and the semiconductor integrated circuit 1. Digital logic circuits 12 and 13 that execute processing for performing a test, and a test pattern generation circuit that generates a test pattern (digital signal) used when testing an analog module including the A / D converter 10 and the D / A converter 11 15 and a determination circuit 14 for determining whether the result pattern (digital signal) obtained when the analog module is tested is good or bad.

  Further, the semiconductor integrated circuit 1 includes a switch 16 that switches a supply source of an analog signal input to the A / D converter 10, a switch 17 that switches a supply destination of an analog signal output from the D / A converter 11, and an A / D A switch 18 for switching a supply destination of a digital signal output from the converter 10, a switch 19 for switching a supply source of a digital signal input to the D / A converter, a determination circuit 14, a test pattern generation circuit 15, and switches 16 to 19. And a test control circuit 20 that controls and realizes a test operation for testing the analog module.

  The switch 16 has one terminal (a terminal) connected to an analog signal supply source connected to the analog input terminal TI, the other terminal (b terminal) connected to the switch 17, and the switch 17 One terminal (a terminal) connected to the supply destination is connected to the analog output terminal TO, and the other terminal (b terminal) is connected to the switch 16.

  The switch 18 has one terminal (a terminal) connected to a digital signal supply destination connected to the digital logic circuit 12, the other terminal (b terminal) connected to the determination circuit 14, and the switch 19 One terminal (a terminal) connected to the digital signal supply source is connected to the digital logic circuit 13, and the other terminal (b terminal) is connected to the test pattern generation circuit 15.

That is, when all of the switches 16 to 19 are set to the a terminal side, an analog signal input from the outside via the analog input terminal TI is A / D converted by the A / D converter 10, and the A The output (digital signal) of the / D converter 10 is supplied to the digital logic circuit 12, and the digital signal output from the digital logic circuit 13 is D / A converted by the D / A converter 11, and the D / A converter 11 outputs (analog signals) are output to the outside via the analog output terminal TO. Hereinafter, this operation is referred to as normal operation.

  On the other hand, when the switches 16 to 19 are all set to the b terminal side, the test pattern generated by the test pattern generation circuit 15 is D / A converted by the D / A converter 11, and the D / A converter 11 is A / D converted by the A / D converter 10, and the output of the A / D converter 10 is supplied to the determination circuit 14. Hereinafter, this operation is referred to as a test operation.

  The test pattern generation circuit 15 is configured to start in response to a command from the test control circuit 20 and generate a digital pattern. However, the value of the digital pattern is changed at regular time intervals so that the entire input range of the D / A converter 11 is covered.

  Similarly to the test pattern generation circuit 15, the determination circuit 14 is activated upon receiving a command from the test control circuit 20, and the test pattern generation circuit 15 generates a result pattern supplied from the A / D converter 10. The analog module (A / D converter 10, D / A converter 11) is determined to be good / bad by determining whether the test pattern matches, and the determination result is output to the test control circuit 20. It is configured as follows.

  However, the term “match” as used herein does not necessarily need to match precisely, and an approximation that is within a preset allowable range may be included in the range of matching. In addition, instead of directly comparing the result pattern and the test pattern, it is possible to determine whether the analog module is good or bad by comparing the operation characteristic obtained from the result pattern with a preset target operation characteristic. .

<Test control circuit>
Next, the operation of the test control circuit 20 will be described along the flowchart shown in FIG.
The test control circuit 20 is realized by a combined circuit set a logic element, to start the power supply to the semiconductor integrated circuit 1 is turned on.

  When the test control circuit 20 is activated, first, all the switches 16 to 19 are set to the normal mode connected to the a terminal side in order to make the above-described normal operation possible (S110).

  Next, the process waits until a start command is input via the test start terminal TS (S120). When the start command is input, all of the switches 16 to 19 are set to enable the above-described test operation. Is set to a test mode connected to the terminal b (S130), and the test pattern generation circuit 15 and the determination circuit 14 are activated (S140). Thereby, a test operation is started.

  Then, it waits until the determination result is output from the determination circuit 14 (S150). When the determination result is output, the test pattern generation circuit 15 and the determination circuit 14 are stopped and the determination result acquired from the determination circuit 14 is displayed. Then, the data is output to the outside via the test result terminal TR (S160), and the process returns to S110.

<Effect>
As described above, when a start command is input from the test start terminal TS, the semiconductor integrated circuit 1 includes the test pattern generation circuit 15, the analog module (A / D converter 10, D / A converter 11), and the determination circuit 14. A loopback path to be connected is set, a test operation is automatically executed, and a measurement result indicating the quality of the operation characteristics of the analog module is output via a test result terminal TR.

  Therefore, according to the semiconductor integrated circuit 1, the analog module can be inspected simply by inputting a start command to the test start terminal TS and monitoring the test result terminal TR, and it is necessary to use an expensive LSI inspection apparatus. Therefore, the inspection cost can be reduced.

[Second Reference Example]
Next, a second reference example will be described.
<Configuration>
FIG. 3 is a block diagram showing a configuration of a main part of the semiconductor integrated circuit 2 of the second reference example .

The semiconductor integrated circuit 2 is different from the semiconductor integrated circuit 1 of the first reference example only in a part of the configuration, and therefore, the same components are denoted by the same reference numerals and description thereof is omitted. The description will focus on the different parts.

  As shown in FIG. 3, the semiconductor integrated circuit 2 includes a CPU 30 instead of the determination circuit 14, the test pattern generation circuit 15, and the test control circuit 20, and signals from the test activation terminal TS and the b terminal of the switch 18 are The test result terminal TR, the b terminal of the switch 19, and the signals to the switches 16 to 19 are directly output from the CPU 30.

  Then, the CPU 30 performs test pattern generation processing for realizing the same function as the test pattern generation circuit 15, determination processing for realizing the same function as the determination circuit 14, and test control for realizing the same function as the test control circuit 20. And at least processing.

<Effect>
As described above, the semiconductor integrated circuit 2 has functions equivalent to those of the determination circuit 14, the test pattern generation circuit 15, and the test control circuit 20 by the processing (software) of the CPU 30 instead of the combination of logic circuits (hardware). Since this is only realized and operates in the same manner as the semiconductor integrated circuit 1 of the first reference example , the same effect can be obtained.

Furthermore, according to the semiconductor integrated circuit 2, since it is not necessary to mount an LSI test circuit, the circuit scale can be reduced and the manufacturing cost can also be reduced.
[First Embodiment]
Next, the first embodiment will be described.

<Configuration>
FIG. 4 is a block diagram illustrating a configuration of a main part of the semiconductor integrated circuit 3 according to the first embodiment .
The semiconductor integrated circuit 3 is different from the semiconductor integrated circuit 2 of the second reference example only in a part of the configuration, and thus the same components are denoted by the same reference numerals and description thereof is omitted. The description will focus on the different parts.

  As shown in FIG. 4, the semiconductor integrated circuit 3 includes an A / D adjustment circuit 31 that variably sets an adjustment parameter that affects the operation characteristics of the A / D converter 10 according to a command from the CPU 30, and the D / A converter 11. And a D / A adjustment circuit 32 that variably sets an adjustment parameter that affects the operation characteristics according to a command from the CPU 30.

  The CPU 30 executes a test pattern generation process and a determination process, and instead of the test control process, the A / D converter 10 and the D / A converter are connected via the A / D adjustment circuit 31 and the D / A adjustment circuit 32. 11 is configured to execute at least a calibration process for adjusting the operation characteristics.

  In the A / D adjustment circuit 31 and the D / A adjustment circuit 32, reference voltage values that are referred to during A / D conversion and D / A conversion are used as adjustment parameters, and the adjustment parameters are changed. Thus, the input / output ranges of the A / D converter 10 and the D / A converter 11 can be adjusted. However, the adjustment parameter is not necessarily limited to the reference voltage value. For example, a bias current value applied to the circuit may be used. In this case, the SNR characteristic and the distortion characteristic can be adjusted (improved).

<Calibration process>
Next, calibration processing executed by the CPU 30 will be described with reference to the flowchart shown in FIG.

  This process is started when a start command is input via the test start terminal TS. In addition, the switches 16 to 19 are set to the normal mode (connected to the terminal a) by the initialization process when the CPU 30 is activated. Further, it is assumed that the determination process is configured not only to determine whether the analog module is good or bad, but also to calculate and output a degree of approximation with a desired operating characteristic.

  When the calibration process is started, first, in S210, the switches 16 to 19 are set to the test mode (connected to the b terminal side), and in subsequent S220, the D / A adjustment parameter is fixed to the current setting value, and the A / The D adjustment parameter is variably set, and the process proceeds to S230. However, the current set value is initially used, and each time this step is repeated thereafter, a value different from the already selected value is selected and set within the adjustment range of the A / D adjustment parameter.

In S230, a test process for starting a test pattern generation process and a determination process to perform a test operation is executed. In S240, based on the result of the test process and the determination result output from the determination process, the operation characteristics of the analog module It is determined whether or not is good.

  If it is determined that the operation characteristics of the analog module are good, the process proceeds to S340, and after the signal indicating that the analog module has been successfully adjusted is output via the test result terminal TR, the process proceeds to S350. If it is determined that the operation characteristics of the analog module are not good, the process proceeds to S250.

  In S250, it is determined whether or not the A / D adjustment parameter has been variably set over the entire adjustable range in S220. If not set, the process returns to S220 to perform A / D adjustment. The parameter is set to a value that has not yet been set, and the processes of S230 to S240 are repeatedly executed. If the parameter has been set, the process proceeds to S260 to obtain the target characteristic obtained for each variable value that is variably set. Is set as the optimum value of the A / D adjustment parameter.

In the subsequent S270, the D / A adjustment parameter is variably set in a state where the A / D adjustment parameter is fixed to the optimum value selected in the previous S260, and the process proceeds to S280.
In S280, the test process is executed in the same manner as in the previous S230, and in the subsequent S290, it is determined whether or not the operation characteristics of the analog module are good based on the result of the test process and the determination result output from the determination process. To do.

If it is determined that the operating characteristics of the analog module are good, the process proceeds to S340. On the other hand, if it is determined that the analog module is not good, the process proceeds to S300.
In S300, it is determined whether or not the D / A adjustment parameter has been set over the entire adjustable range in S270. If not, the process returns to S270 to return to the D / A adjustment parameter. Is set to a value that has not yet been set, and the processing of S270 to S290 is repeatedly executed. If it has been set, the flow proceeds to S310, and the target characteristic obtained for each variably set value is obtained. Based on the degree of approximation, the value having the largest degree of approximation is set as the optimum value of the D / A adjustment parameter.

  In the subsequent S320, it is determined whether or not the number of repetitions of the processing in S220 to S310 has reached a preset specified number (for example, 10 times). If the specified number has not been reached, the process returns to S220, If the process of S220 to S310 is repeated and the specified number of times has been reached, the process proceeds to S330, and after outputting a signal indicating that the analog module adjustment has failed through the test result terminal TR, the process proceeds to S340.

In S340, the switches 16 to 19 are returned to the normal mode (connected to the terminal a), and this process is terminated.
<Effect>
As described above, when the operation characteristic of the analog module does not match the target characteristic, the semiconductor integrated circuit 3 performs the test process while fixing one adjustment parameter and variably setting the other adjustment parameter. The optimum value of the other adjustment parameter is obtained from the obtained determination result (including the degree of approximation). Next, the fixed side and the variable setting side are switched, and the fixed side can obtain the adjustment parameter in the immediately preceding process. perform similar processing was fixed to the optimum value, which, using the adjustment parameter operating characteristics of the analog module is set when a match with the target characteristic, such that the process in the normal mode Has been.

  Therefore, according to the semiconductor integrated circuit 3, the operation characteristics of the A / D converter 10 and the D / A converter 11 are automatically adjusted by executing the calibration process, and an expensive LSI inspection apparatus is used for this adjustment. Therefore, the labor and cost required for adjustment can be greatly reduced.

  In addition, according to the semiconductor integrated circuit 3, by performing calibration processing at an appropriate timing, not only process variations and characteristic changes due to aging can be corrected, but also characteristics caused by temperature fluctuations and power supply voltage fluctuations. Variations can also be corrected.

  In the present embodiment, the calibration process is configured to be executed when a start command is input via the test start terminal TS. For example, the calibration process may be executed at predetermined intervals, It may be configured to execute at an apparent timing that no analog signal is input / output via the analog input terminal TI and the analog output terminal TO.

  Further, the semiconductor integrated circuit 3 of the present embodiment stores the A / D adjustment parameter and the D / A adjustment parameter obtained by executing the calibration process in a nonvolatile memory built in the semiconductor integrated circuit 3. It may be configured to. In this case, when the power supply of the semiconductor integrated circuit 3 is turned off, the adjustment parameter obtained by the calibration process can be held, and when the power supply is turned on later, it is stored in the nonvolatile memory. The A / D converter 10 and the D / A converter 11 can be operated immediately using the adjustment parameters.

[Second Embodiment]
Next, a second embodiment will be described.
FIG. 6 is a block diagram showing a configuration of a main part of the semiconductor integrated circuit 4 of the second embodiment .

The semiconductor integrated circuit 4 is different from the semiconductor integrated circuit 1 of the first reference example only in a part of the configuration, and thus the same components are denoted by the same reference numerals and description thereof is omitted. The description will focus on the different parts.

  As shown in FIG. 6, the semiconductor integrated circuit 4 has two analog input terminals TI and TIa, and an A / D converter 10 a configured in the same manner as the A / D converter 10, the switches 16 and 18, and the determination circuit 14. , Switches 16a and 18a, and a determination circuit 14a.

  In the switch 16a for switching the supply source of the analog signal input to the A / D converter 10a, the a terminal is connected to the analog input terminal TIa, the b terminal is connected to the b terminals of the switches 16 and 17, and the A / D converter 10a The switch 18a for switching the supply destination of the output digital signal has an a terminal connected to the digital logic circuit 12a and a b terminal connected to the determination circuit 14a.

  That is, when the switches 16 to 19 and 16a and 18a are all set to the b terminal side, the test pattern generated by the test pattern generation circuit 15 is D / A converted by the D / A converter 11, The output of the D / A converter 11 is A / D converted by the two A / D converters 10 and 10a, the output of the A / D converter 10 is sent to the decision circuit 14, and the output of the A / D converter 10a is the decision circuit. 14a.

Then, the test control circuit 21 executes the same processing (see FIG. 2) as the test control circuit 20 in the first reference example . However, in S150, the process waits until the determination results are acquired from both of the two determination circuits 14 and 14a. In S160, when both of the acquired two determination results indicate that the operation characteristics are good, A determination result indicating that the analog modules (A / D converters 10 and 10a, D / A converter 11) are non-defective products is output via a test result terminal TR.

<Effect>
As described above, the semiconductor integrated circuit 4 includes the two A / D converters 10 and 10a, the first analog module including the D / A converter 11 and the A / D converter 10, and the D / A converter 11 and A. A test operation similar to that in the first reference example is performed in parallel for the second analog module including the / D converter 10a.

Therefore, according to the semiconductor integrated circuit 4, the same effect as the semiconductor integrated circuit 1 of the first reference example can be obtained.
In the present embodiment, the case where the two A / D converters 10 and 10a are provided has been described. However, even when three or more A / D converters are provided, the same configuration is possible.

[Third Embodiment]
Next, a third embodiment will be described.
FIG. 7 is a block diagram showing a configuration of a main part of the semiconductor integrated circuit 5 of the third embodiment .

The semiconductor integrated circuit 5 is different from the semiconductor integrated circuit 1 of the first reference example only in a part of the configuration, and thus the same components are denoted by the same reference numerals and the description thereof is omitted. The description will focus on the different parts.

  As shown in FIG. 7, the semiconductor integrated circuit 5 has two analog output terminals TO and TOa, and has a D / A converter 11a, a switch 17a, 19a is provided.

  The switch 19a for switching the supply source of the digital signal input to the D / A converter 11a has an a terminal connected to the digital logic circuit 13a and a b terminal connected to the test pattern generation circuit 15, and is output from the D / A converter 11a. In the switch 17a for switching the analog signal supply destination, the a terminal is connected to the analog output terminal TOa, and the b terminal is connected to the b terminals of the switches 16 and 17.

In the semiconductor integrated circuit 5, the switches 17, 19 and the switches 17a, 19a are not set to the b terminal side at the same time.
That is, when the switches 16 to 19 are set to the b terminal side (that is, the switches 17a and 19a are set to the a terminal side) (hereinafter referred to as the first loopback setting), the same test as in the first reference example is performed. When the switches 16, 17 a, 18, 19 a are set to the b terminal side (that is, the switches 17, 19 are set to the a terminal side) (hereinafter referred to as second loopback setting), the test pattern generation circuit 15 The test pattern is the same as that in the first reference example except that the D / A conversion is performed by the D / A converter 11a.

Then, the test control circuit 22, the processing of S130～S150 in Figure 2, perform respectively the first loopback configuration and second loop back setting described above (i.e., repeated twice), in S160, S130～S150 When the two determination results obtained by repeating the above process twice indicate that the operation characteristics are good, the analog module (A / D converter 10, D / A converters 11, 11a) A determination result indicating that the product is non-defective is output via a test result terminal TR.

<Effect>
As described above, the semiconductor integrated circuit 5 includes the two D / A converters 11 and 11a, the first analog module including the D / A converter 11 and the A / D converter 10, and the D / A converters 11a and A. For the second analog module comprising the / D converter 10, the same test operation as that in the first reference example is performed one by one.

Therefore, according to the semiconductor integrated circuit 5, the same effect as that of the semiconductor integrated circuit 1 of the first reference example can be obtained.
In the present embodiment, the case where the two D / A converters 11 and 11a are provided has been described. However, even when three or more D / A converters are provided, the same configuration is possible.

<Other embodiments>
Although several embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the gist of the present invention. .

For example, the second, the third embodiment, the test control circuits 21 and 22, the determination circuit 14, 14a, a combination of logic circuit test pattern generating circuit 15 (i.e., hardware) has been realized by the second reference For example, as in the case of the first embodiment, the functions of these circuits may be realized by processing (ie, software) executed by the CPU.

  DESCRIPTION OF SYMBOLS 1-5 ... Semiconductor integrated circuit 10, 10a ... A / D converter 11, 11a ... D / A converter 12, 12a, 13, 13a ... Digital logic circuit 14, 14a ... Decision circuit 15 ... Test pattern generation circuit 16-19, 16a to 19a ... switch 20-22 ... test control circuit 31 ... A / D adjustment circuit 32 ... D / A adjustment circuit

Claims (4)

An analog input terminal provided for inputting an analog signal;
An analog output terminal provided for outputting an analog signal;
A signal processing unit for processing a digital signal;
By changing preset adjustment parameters for A / D, the operation characteristics can be adjusted. Analog signals input via the analog input terminal are converted into digital signals and supplied to the signal processing unit An A / D converter to
By changing preset adjustment parameters for D / A, the operation characteristics can be adjusted. The digital signal supplied from the signal processing unit is converted into an analog signal and output through the analog output terminal. D / A converter to
In a semiconductor integrated circuit comprising:
Path setting means for setting a loopback path in which the output of the D / A converter is input to the A / D converter at a preset adjustment timing;
When the loopback path is set by the path setting means, a preset test pattern is input to the D / A converter, a result pattern output from the A / D converter is acquired, and the result pattern The A / D adjustment parameter and the D / A adjustment are determined so that the characteristics of the loopback system including the D / A converter and the A / D converter specified by the above match the preset target characteristics. Adjustment means for setting parameters;
Provided ,
The adjusting means includes
Of the A / D adjustment parameter and the D / A adjustment parameter, one is a first parameter, the other is a second parameter, the second parameter is fixed, and the first parameter is changed to change the loop A first parameter adjusting means for repeatedly measuring the characteristics of the back system and selecting the optimum value of the first parameter from the measurement result;
The first parameter is fixed to the optimum value selected by the first parameter adjusting means, and the characteristics of the loopback system are repeatedly measured by changing the second parameter. A second parameter adjusting means for selecting an optimum value;
The semiconductor integrated circuit comprising: a. The adjusting means includes
2. The semiconductor integrated circuit according to claim 1 , wherein the first parameter adjusting means and the second parameter adjusting means are repeatedly executed alternately within a preset upper limit number of times. An adjustment result output terminal for outputting the adjustment result by the adjusting means is provided,
The said adjustment means outputs the signal showing whether the characteristic of the said loopback system was made to correspond with the said target characteristic as the said adjustment result, The Claim 1 or Claim 2 characterized by the above-mentioned. Semiconductor integrated circuit. Semiconductor according to any of claims 1 to 3, characterized in that it comprises an adjustment parameter storage means for storing the for A / D adjustment parameters and adjustment parameters for the D / A is set by the adjusting means Integrated circuit.

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