JP2004014786A - Semiconductor integrated circuit and method for adjusting analog circuit characteristic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily adjust various characteristics of analog circuits built in an LSI after manufactured without modifying the circuits or the like. <P>SOLUTION: A register for holding a set point given from the outside is prepared and a set point is held in the register. A characteristic adjustment signal corresponding to the set point is sent out to the analog circuit to vary the characteristics of the analog circuit. This easily adjusts the various characteristics of the analog circuit built in the LSI after manufactured without modifying the circuits or the like. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor integrated circuit (LSI) mounted on a wireless card used in a wireless communication system, and in particular, to an analog circuit characteristic for adjusting characteristics of an analog circuit formed inside the LSI mounted on the wireless card. Regarding the adjustment method.
[0002]
[Prior art]
Normally, in designing an analog circuit of an LSI, the characteristics are adjusted in consideration of a temperature variation, a process variation (Vth), and the like by a preliminary simulation or the like. However, even in an actual LSI, desired characteristics are not obtained. Adjustments may be required.
[0003]
An LSI mounted with a wireless card (wireless data carrier) has a function of performing wireless communication (reading / writing of memory data) with an RWU (Reader / Writer Unit) and receiving power for operating the LSI from the RWU. In order to realize these functions, an analog circuit is formed inside.
[0004]
In such a wireless card, the characteristics of analog circuits for transmission and reception are different between a place where the distance to the RWU is short and a place where the distance is far (the distance is disadvantageous when the distance is adjusted to a short distance, and is disadvantageous when the distance is adjusted to a long distance. Various circuit characteristics are required depending on the intended use and situation.
[0005]
Therefore, in this type of transmission / reception analog circuit, it is necessary to finely adjust the various circuit characteristics described above, for example, the degree of transmission modulation and the width of hysteresis of the comparator. Further, the wireless card obtains electric power from the RWU by electromagnetic induction in order to operate the mounted LSI, but it is necessary to adjust characteristics of a regulator used in the power receiving circuit.
[0006]
[Problems to be solved by the invention]
In the conventional analog circuit adjustment as described above, the circuit is formed in advance using a redundant circuit or element, and then, if necessary, the characteristics of the analog circuit described above are adjusted using the redundant circuit or element. Was. However, with such an adjustment method, only a part of the characteristic to be adjusted can be adjusted, and after being incorporated into the product, the characteristic of the regulator is adjusted in real time according to the distance from the RWU. I couldn't do anything at all. In addition, it takes about one month to more time from the correction of the circuit and wiring by the above-described conventional method to the manufacture of the corrected LSI, and the cost of mask correction and LSI manufacture is high. However, there is a problem that the cost of the final product is increased accordingly.
[0007]
The present invention has been made to solve the conventional problems as described above, and an object of the present invention is to easily adjust various characteristics of an analog circuit incorporated in an LSI after manufacturing without modifying the circuit. A semiconductor integrated circuit and an analog circuit characteristic adjusting method capable of adjusting the characteristics of the analog circuit so as to obtain the best characteristics according to the situation during operation after being incorporated into a product. That is.
[0008]
[Means for Solving the Problems]
A first means for solving the problems is a semiconductor integrated circuit having an analog circuit, wherein a holding means for holding an externally applied set value, and a characteristic adjustment signal corresponding to the set value held by the holding means To the analog circuit, and a characteristic change circuit incorporated in the analog circuit for changing the characteristic of the analog circuit according to the transmitted characteristic adjustment signal.
[0009]
When the set value is held in the holding means by the above means, a characteristic adjustment signal corresponding to the set value is sent to the analog circuit, and for example, the transmission modulation degree of the analog circuit is changed. The holding means corresponds to the register group 4 of the embodiment, the adjusting means corresponds to the control circuit 3 of the embodiment, and the characteristic changing circuit corresponds to switches SW1 to SWn and resistors r1 to rn.
[0010]
The second means is a method for adjusting the characteristic of an analog circuit formed in a semiconductor integrated circuit, wherein the step of wirelessly transmitting a set value and the step of receiving the wirelessly transmitted set value Holding the received set value, and changing a characteristic of the analog circuit according to the held set value.
[0011]
When the setting value is wirelessly transmitted from the RWU or the like by the above means, the semiconductor integrated circuit mounted on the wireless card receives the wirelessly transmitted setting value, holds the received setting value, and holds the held setting value. The characteristic of the analog circuit is changed according to the set value.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of an LSI for a wireless card equipped with an analog circuit according to the first embodiment of the present invention. The wireless card LSI (sometimes simply referred to as LSI) 100 includes a transmitting / receiving analog circuit 1 for wirelessly transmitting and receiving data, a power supply circuit (analog circuit) 2 for receiving power from an RWU (not shown) to generate an operation power supply, A control circuit 3 for adjusting the characteristics of the analog circuit 1, a register group 4 for changing the characteristics for holding the set values of the transmitting and receiving analog circuits 1, and a rewritable nonvolatile memory (EEPROM) for storing the set values to be written in the register group 4. 5. It has a CPU 6 for controlling the operation of the LSI 100.
[0013]
Next, the operation of the present embodiment will be described. The wireless card LSI 100 of this example is configured in advance so that the characteristics of the transmission / reception analog circuit 1 can be changed, and the control circuit 3 has a register group 4 for setting the characteristics of the transmission / reception analog circuit 1. is there. Here, adjustment of the characteristics of the voltage detection level of the power supply voltage detection circuit 11 shown in FIG. 2 included in the analog circuit 1, for example, will be described.
[0014]
For example, the measurement and evaluation results after the manufacture of the LSI show that the power supply voltage detection level of the power supply voltage detection circuit 11 is lower than the target by 100 mV, and when it is desired to shift by +100 mV, the power supply voltage detection level is set to +100 mV in the nonvolatile memory 5. The set value to be shifted is stored.
[0015]
Thereafter, when a predetermined power supply voltage is generated in the power supply circuit 2, the LSI 100 starts up, and the control circuit 3 reads out the set value of the nonvolatile memory 5 and writes the set value in a predetermined register of the register group 4. Further, the control circuit 3 adjusts the characteristic to shift the power supply voltage detection level of the power supply voltage detection circuit 11 by +100 mV based on the set value written in the register. This characteristic adjustment is performed by sending a characteristic adjustment signal corresponding to the register value from the control circuit 3 to the power supply voltage detection circuit 11 such that the register value is a power supply voltage adjustment signal 0, a power supply voltage adjustment signal 1,. Done. As a result, the power supply voltage detection circuit 11 detects the power supply voltage level as specified, and outputs the power supply voltage detection signal 50.
[0016]
FIG. 3 is a circuit diagram showing a specific circuit configuration example for performing characteristic adjustment for shifting the power supply voltage detection level of the power supply voltage detection circuit 11 by +100 mV. This example is a voltage dividing circuit including resistors R1 and R2 for generating a reference potential of a detection level. This resistor R1 has a plurality of series circuits including switches SW1, SW2,..., SWn and resistors r1, r2,. Circuits are connected in parallel.
[0017]
The switches SW1, SW2,..., And SWn are turned on and off by a power supply voltage adjustment signal 0, a power supply voltage adjustment signal 1,. By turning on and off these switches SW1, SW2,..., SWn, the resistance value between the power supply voltage VDD and the resistor R2 changes, so that the reference value potential of the detection level of the power supply voltage detection circuit 11 changes and the power supply The power supply voltage detection level of the voltage detection circuit 11 can be shifted to a desired value.
[0018]
FIG. 4 is a block diagram for explaining the operation of the above-described wireless card LSI 100 at the time of startup. (1) When a voltage necessary for the operation of the LSI 100 is obtained by the power supply circuit 2 (see FIG. 1), the reset of the LSI 100 is released. (2) The control circuit 3 issues a control signal for reading the register setting value 80 stored in the nonvolatile memory 5. (3) The register set value 80 is read from the nonvolatile memory 5 and stored in a predetermined register of the register group 4 for controlling analog circuit characteristics. (4) The power supply voltage detection level adjustment signal is sent from the control circuit 3 to the power supply voltage detection circuit 11 in accordance with the set value stored in the analog circuit characteristic control register, and the characteristics of the power supply voltage detection circuit 11 are adjusted. You.
[0019]
Therefore, if the set value of the characteristic variable register is written in the system area of the non-volatile memory 5 as described above, the written value is automatically transferred to the control circuit 3 before the first communication after the LSI 100 is started. Is read and stored in the characteristic variable register, so that the transmission / reception analog circuit 1 always operates with the adjusted characteristics.
In the above description, the correction of the detection level of the power supply voltage detection circuit 11 has been described. The characteristic adjustment of the transmission / reception analog circuit 1 is performed by a method of writing a set value to the register group 4 similar to the above, although there are various types such as a hysteresis width of a comparator, a modulation degree at the time of transmission, or a characteristic of a regulator of the power supply circuit 2. Adjustments can be made.
[0020]
According to the present embodiment, various characteristic adjustments of the transmission / reception analog circuit 1 and the power supply circuit 2 built in the LSI 100 can be easily performed after manufacturing by simply writing the set value to the register group 4 without modifying the circuit. be able to. Therefore, since it is not necessary to manufacture a modified LSI by modifying the circuit or wiring and modifying the mask as in the conventional case, it is not necessary to manufacture a modified LSI, so that the production period of the final product can be significantly shortened and the product cost can be reduced. it can. Further, it is possible to manufacture an LSI having various characteristics according to a use or the like in a short time and at a low cost.
[0021]
FIG. 5 is a block diagram showing a configuration example of a wireless system including a wireless card equipped with an analog circuit according to the second embodiment of the present invention. The wireless system includes a wireless card 10 and an RWU 20, and data is transmitted and received between the two.
[0022]
FIG. 6 is a block diagram showing a configuration example of an LSI mounted on the wireless card 10. However, the same parts as those in the first embodiment shown in FIG. The LSI 100 includes a transmission / reception analog circuit 1 having a power supply voltage detection circuit 11, a control circuit 3 having a register group 4, and a rewritable non-volatile memory (for example, an EEPROM) 5 for storing setting values to be written in the register group 4. I have.
[0023]
Next, the operation of the present embodiment will be described. The RWU 20 of the present example transmits a command to the LSI 100 even when the LSI 100 mounted on the wireless card 10 is operating, and changes the characteristics of the transmission / reception analog circuit 1 and the like in real time in the best state according to the situation. Can be changed to
[0024]
Here, a command dedicated to register value setting may be provided in a command transmitted from the RWU 20 to the LSI 100, or may be incorporated in a part of a normal command. When a dedicated command is used, a register setting command, which is a dedicated command for setting a register value, is provided in a communication command group such as a memory read command, a memory write command, and a card reset command.
[0025]
On the other hand, when incorporated in a part of a normal command, a data string for setting the register value of the register group 4 is set as a part of a data string of a communication command such as a memory read or a memory write in FIG. Assemble as shown.
[0026]
Using the command as described above, the RWU 20 can control the characteristics of the transmitting and receiving analog circuit 1 of the LSI 100 during communication with the wireless card 10. For example, when the wireless card 10 is located far from the RWU 20, the transmission modulation degree of the transmission / reception analog circuit 1 can be increased to increase the communication distance. However, in this case, a mechanism for recognizing that the distance between the RWU 20 and the wireless card 10 has become longer is separately required.
[0027]
In order for the RWU 20 to control the characteristics of the transmission / reception analog circuit 1 during communication with the wireless card 10, in FIG. 6, (1) the transmission / reception analog circuit 1 of the LSI 100 of the wireless card 10 sets a register value from the RWU 20 (data example). ) Command. (2) The register setting value is extracted from the command received by the control circuit 3 and stored in a predetermined register of the register group 4 for analog circuit characteristic control. (3) The power supply voltage detection level setting signal is output from the control circuit 3 to the power supply voltage detection circuit 11 in accordance with the value stored in the register group 4, and the characteristics of the power supply voltage detection circuit 11 are changed and adjusted.
[0028]
By the above operation, the RWU 20 is adjusted in real time according to the distance from the wireless card 10 and the like so that the characteristics of the transmission / reception analog circuit 1 become the best. Accordingly, (4) a control signal for writing the value stored in the register group 4 for analog circuit characteristic control to the nonvolatile memory 5 is output from the control circuit 3 to the nonvolatile memory 5. (5) The value stored in the register group 4 for controlling analog circuit characteristics is written to the nonvolatile memory 5. After the setting value is written in the nonvolatile memory 5, the operation as described with reference to FIG. 4 of the first embodiment is performed.
[0029]
According to the present embodiment, the RWU 20 can adjust the characteristics of the transmission / reception analog circuit 1 in real time according to the distance from the wireless card 10 and the like, so that the characteristics are the best. Similarly, various characteristics of the analog circuit can be adjusted so as to obtain the best characteristics according to the situation even after being incorporated in the product, and the performance of the wireless card 10 and the like can be significantly improved.
[0030]
The present invention is not limited to the above-described embodiment, and may be embodied in other various forms in specific configurations, functions, operations, and effects without departing from the gist of the invention. The present invention can be applied not only to an LSI mounted on a wireless card but also to various LSIs to obtain a similar effect.
[0031]
【The invention's effect】
As described above in detail, according to the present invention, by holding a set value given from the outside and changing the characteristics of the analog circuit according to the set value, the LSI can be implemented without circuit modification or the like. Various characteristics adjustment of the built-in analog circuit can be easily performed after manufacturing.
[0032]
Further, according to the present invention, by holding an appropriate set value during operation of the LSI, it is possible to easily adjust various characteristics of an analog circuit built in the LSI according to the situation during operation after manufacturing. Can be.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration example of a wireless card LSI on which an analog circuit according to a first embodiment of the present invention is mounted.
FIG. 2 is an explanatory diagram for explaining characteristic adjustment of a voltage detection level of the analog circuit shown in FIG. 1;
3 is a circuit diagram showing a specific circuit configuration example for changing a power supply voltage detection level of the power supply voltage detection circuit shown in FIG. 2;
FIG. 4 is a block diagram illustrating an operation of the wireless card LSI shown in FIG. 1 at the time of startup.
FIG. 5 is a block diagram showing a configuration example of a wireless system including a wireless card equipped with an analog circuit according to a second embodiment of the present invention.
6 is a block diagram illustrating a configuration example of an LSI mounted on the wireless card illustrated in FIG. 5;
FIG. 7 is a diagram showing a configuration example of a command transmitted from the RWU shown in FIG. 5 to the wireless card.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Transmission / reception analog circuit 2 Power supply circuit 3 Control circuit 4 Register group 5 Non-volatile memory 6 CPU
10 wireless card 11 power supply voltage detection circuit 20 RWU

Claims (6)

In a semiconductor integrated circuit having an analog circuit,
Holding means for holding a setting value given from the outside,
Adjusting means for sending a characteristic adjustment signal according to the set value held by the holding means to the analog circuit;
A characteristic change circuit incorporated in the analog circuit that changes the characteristic of the analog circuit according to the transmitted characteristic adjustment signal;
A semiconductor integrated circuit comprising: 2. The semiconductor integrated circuit according to claim 1, wherein a radio signal receiving circuit is provided in the analog circuit, and the holding unit holds the set value received by the receiving circuit. Providing a rewritable nonvolatile memory for writing a set value held in the holding means,
3. The semiconductor integrated circuit according to claim 1, wherein the holding unit reads and holds a set value in the nonvolatile memory when the semiconductor integrated circuit is started. The semiconductor integrated circuit according to claim 1, wherein the semiconductor integrated circuit is mounted on a wireless card. An analog circuit characteristic adjusting method for adjusting characteristics of an analog circuit formed in a semiconductor integrated circuit,
Wirelessly transmitting the setting value;
Receiving the wirelessly transmitted setting value;
Holding the received setting value;
Changing the characteristic of the analog circuit according to the held set value;
A method for adjusting analog circuit characteristics, comprising: 6. The analog circuit characteristic adjusting method according to claim 5, wherein when the set value is wirelessly transmitted, a command instructing to adjust the characteristic of the analog circuit using the set value is wirelessly transmitted.

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