JP3509412B2 - Impedance adjustment circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impedance adjusting circuit, and more particularly, a resistance value is adjusted by connecting a plurality of resistors in parallel with an adjusting terminal in advance and disconnecting the plurality of resistors. The present invention relates to an impedance adjusting circuit.

[0002]

2. Description of the Related Art Various driving power supply voltages for driving an IC (Integrated Circuit) are set according to the power supply and the like.
For this reason, it is required that the manufactured IC also be developed according to the power supply voltage.

FIG. 7 shows a circuit configuration diagram of a conventional impedance adjusting circuit. Conventional impedance adjustment circuit 41
Is formed on the semiconductor chip, is connected to an internal circuit formed on the semiconductor chip, and adjusts the impedance of the internal circuit.

The impedance adjusting circuit 41 includes a resistor R41.
.About.R44 are connected in parallel between the adjusting terminals TA and TB connected to the internal circuit, and the resistors R41 to R44 are disconnectable from the adjusting terminals TA and TB. Wiring 4 for short circuit between the adjustment terminal TA and the adjustment terminal TB
2 is connected. A laser shot location LZ44 is set on the short-circuit wiring 42. The laser shot location LZ44 is cut except when the impedance between the adjusting terminal TA and the adjusting terminal TB is set to 0, that is, in the short-circuited state.

The resistor R44 is connected between the adjusting terminal TA and the adjusting terminal TB, and is provided between the adjusting terminal TA and the adjusting terminal T.
The maximum resistance value r with B is set. Resistance R
The resistance value of 43 is set to the same resistance value r as the resistance R44, one end is connected to the adjustment terminal TA via the adjustment wiring 43, and the other end is directly connected to the adjustment terminal TB. The adjustment wiring 43 is provided with a laser shot location LZ43. The laser shot location LZ43 has a maximum resistance R44 = r between the adjustment terminal TA and the adjustment terminal TB, or a parallel combined resistance of the resistances R44 and R43, or a resistance R44,
It is cut off when obtaining the combined resistance of R43 and R42.

The resistance value of the resistor R42 is set to the same resistance value r as that of the resistors R44 and R43, and one end thereof is connected to the connection point between one end of the resistor R43 and the adjustment wiring 43 via the adjustment wiring 44. , The other end is directly connected to the adjustment terminal TB. A laser shot location LZ42 is set on the adjustment wiring 44. The laser shot location LZ42 is cut when obtaining a parallel combined resistance of the resistance R44 and the resistance R43.

The resistance of the resistor R41 is R44, R43, R.
The resistance value r is the same as that of 42, one end of which is connected to the connection point between one end of the resistor R42 and the adjustment wiring 44 via the adjustment wiring 45, and the other end is directly connected to the adjustment terminal TB. It A laser shot portion LZ41 is provided on the adjustment wiring 45.
Is set. The laser shot location LZ41 is cut when obtaining the parallel combined resistance of the resistances R44, R43 and R42.

Next, the conventional impedance adjusting circuit 41
The operation of will be described. When the impedance adjustment circuit 41 obtains the lowest impedance, laser shot is not performed on any of the laser shot locations LZ41, LZ42, LZ43, and LZ44. Laser shot location LZ
41, LZ42, LZ43, and LZ44 are not laser-shot, so that the adjustment wirings 42, 43, 4
Neither 4 nor 45 is cut. When none of the adjustment wirings 42, 43, 44, and 45 is cut, the adjustment wiring 42 is connected between the adjustment terminal TA and the adjustment terminal TB, so that the adjustment terminal TA and the adjustment terminal It is short-circuited to TB and impedance is 0.
It is said that

Further, when the maximum impedance is obtained by the impedance adjusting circuit 41, laser shots are made at two laser shot locations LZ43 and LZ44.
The adjustment wirings 42 and 43 are cut by performing laser shots on the laser shot locations LZ43 and LZ44. By cutting the adjustment wires 42 and 43, only the resistor R44 is connected between the adjustment terminal TA and the adjustment terminal TB, and the other resistors R43, R42, and R41 may be connected in parallel. Therefore, the resistance value r of the resistor R44 is connected as the maximum impedance.

Further, in the case of obtaining an intermediate impedance, only one of the laser shot spot LZ44, the laser shot spot LZ44, and LZ41 or LZ42 is used.
Make a laser shot on the spot. For example, if a laser shot is performed on one of the laser shot locations LZ44, a resistance R is placed between the adjustment terminal TA and the adjustment terminal TB.
Since 41, R42, R43, and R44 are connected in parallel, resistors R41, R42, and R42 are provided between the adjustment terminal TA and the adjustment terminal TB.
The parallel combined resistance RAB of R43 and R44 is

[0011]

[Equation 2]

Are connected. Here, the resistors R41, R42,
Since the resistance values of R43 and R44 are all r, the formula (1) is

[0013]

[Equation 3]

[0014] Also, the laser shot location LZ
When laser shots are performed on 44 and LZ41, a resistance R is placed between the adjustment terminal TA and the adjustment terminal TB.
Since 42, R43, and R44 are connected in parallel, the adjustment terminal T
Between A and the adjustment terminal TB, the parallel combined resistance RAB of the resistances R42, R43, and R44 is

[0015]

[Equation 4]

Are connected. Here, the resistors R42, R43,
Since all the resistance values of R44 are r, the formula (3) is

[0017]

[Equation 5]

[0018] Furthermore, the laser shot location L
When laser shots are made at two points Z44 and LZ42, a resistance R is placed between the adjustment terminal TA and the adjustment terminal TB.
Since 43 and R44 are connected in parallel, the parallel combined resistance RAB of the resistors R43 and R44 is between the adjustment terminal TA and the adjustment terminal TB.

[0019]

[Equation 6]

Are connected. Here, since the resistance value of the resistors R43 and R44 is r, the equation (5) is

[0021]

[Equation 7]

It becomes Therefore, the resistance value RAB that can be adjusted by the impedance adjustment circuit 41 is 0, r / 4, r / 3, r / 2, r.

FIG. 8 is a diagram showing the relationship between the cut point and the impedance of the conventional impedance adjusting circuit. Figure 8
Is the resistance value of the resistors R41, R42, R43, R44 r = 140
The combined resistance RAB when KΩ is shown.

As shown in FIG. 8, a laser shot point L
When only Z44 is cut, the combined resistance RA B is calculated from equation (2).
Is r / 4 = 140K / 4 = 35KΩ. Also,
When the laser shot locations LZ44 and LZ41 are cut, the combined resistance RAB is r / 3 = 140K from equation (4).
/ 3 = 47 KΩ.

Further, when the laser shot points LZ44 and LZ42 are cut, the combined resistance RAB is obtained from the equation (6).
Is set to r / 2 = 140K / 2 = 70KΩ. As described above, in the conventional impedance adjusting circuit 41, the resistance value that can be adjusted is r / n (n is a positive integer).
The difference in the combined resistance that can be adjusted is 12KΩ, 23
It becomes KΩ and 70KΩ and cannot be set uniformly.

[0026]

However, in the conventional impedance adjusting circuit, the resistors connected in parallel to the adjusting terminals are all set to the same resistance value r.
The difference in the combined resistance that can be adjusted is 12KΩ, 23
KΩ and 70KΩ, which cannot be set uniformly. Therefore, if you want to set a large adjustment impedance, as shown in FIG. 8, between 70KΩ and 140KΩ is 70K.
There was a difference of Ω, and it was not possible to make fine adjustments.

The present invention has been made in view of the above points, and it is an object of the present invention to provide an impedance adjustment circuit capable of uniform impedance adjustment with a minimum number of cutting points.

[0028]

According to a first aspect of the present invention, N resistors are connected in parallel between adjustment terminals, and the adjustment is performed by disconnecting the n resistors from the adjustment terminals. In the impedance adjustment circuit for adjusting the impedance between the terminals, the resistance values of the N resistors are set so that the resistance values of the adjustment terminals can be adjusted with a constant difference.

In the second aspect, the maximum possible resistance value is rma.
x is the resistance R among the N resistances R1 to Rn.
n is set to the maximum value rmax, and the other (N-1) resistors R
The resistance value rx of 1 to Rn-1

[0030]

[Equation 8]

It is characterized in that it is set to. Claim 3
Connects the N resistors to the resistors having the resistance value rm set between the adjustment terminals, and the other resistors have the resistance value rm.
Is configured to be sequentially connected to one end of the resistor in the preceding stage via a wiring that can be cut from the set resistor in descending order of resistance value.

A fourth aspect of the present invention is characterized in that the N resistors are connected in parallel between the adjusting terminals via wirings capable of cutting the N resistors. A fifth aspect of the present invention is characterized in that the adjustment terminals are short-circuited by a disconnectable wiring.

According to the present invention, when the maximum resistance value that can take the resistance value of the N resistors is rm, the resistance value of one of the N resistors is set to rm, and the other resistance value is set to rm. (N-
1) Set the resistance value rx of each of the resistors R1 to Rn-1

[0034]

[Equation 9]

The resistance value of the adjustment terminal can be adjusted with a constant difference by setting to (1) and selectively cutting the resistance.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a circuit configuration diagram of a first embodiment of the present invention. Impedance adjusting circuit 11 of the present embodiment
Is formed on the semiconductor chip, is connected to an internal circuit formed on the semiconductor chip, and adjusts the impedance of the internal circuit.

The impedance adjusting circuit 11 has an adjusting terminal TA for connecting n resistors R11 to R1n to an internal circuit.
Resistors R11 to R1n are connected in parallel between TB.
Is configured so that it can be disconnected from the adjustment terminals TA and TB. A short circuit wire 12-n is connected between the adjusting terminal TA and the adjusting terminal TB. This short circuit wiring 12
A laser shot location LZ1n is set to -n. The laser shot location LZ1n is cut off except when the impedance between the adjustment terminal TA and the adjustment terminal TB is set to 0, that is, in the short-circuited state.

The resistor R1n is connected between the adjusting terminal TA and the adjusting terminal TB, and is connected between the adjusting terminal TA and the adjusting terminal T.
The maximum resistance value r1n between B and B is set. The resistance value of the resistor R1n-1 is set to a resistance value rn-1 different from that of the resistor R1n, one end is connected to the adjustment terminal TA via the adjustment wiring 12-n-1, and the other end is directly connected. Adjustment terminal TB
Connected to. A laser shot location LZ1n-1 is provided on the adjustment wiring 12-n-1. The laser shot portion LZ1n-1 is cut when the maximum resistance R1n = r is obtained between the adjusting terminal TA and the adjusting terminal TB.

Similarly, the resistors R14 to R1n-2 are connected. The resistance value of the resistor R13 is set to a resistance value r13 different from the resistance values of the resistors R14 to R1n, and one end of the adjustment wire 1 is used.
It is connected via a 2-3 to the connection point between one end of the resistor R14 and the adjustment wiring 12-4, and the other end is directly connected to the adjustment terminal TB. A laser shot location LZ13 is set on the adjustment wiring 12-3. Laser shot location LZ
13 is cut off when obtaining a parallel combined resistance of the resistance R14 to the resistance R1n.

The resistance value of the resistor R12 is set to a resistance value r12 different from that of the resistors R13 to R1n, and one end of the resistor R13 and the adjustment wiring 12-3 are connected through the adjustment wiring 12-2.
And the other end is directly connected to the adjustment terminal TB. A laser shot location LZ12 is set on the adjustment wiring 12-2. Laser shot point L
Z12 is cut off when obtaining the parallel combined resistance of the resistances R13 to R1n.

The resistance value of the resistor R11 is set to a resistance value r11 which is different from the resistance values of the resistors R12 to R1n, and one end of the resistor R12 and the adjustment wiring 12-2 are connected via the adjustment wiring 12-1.
And the other end is directly connected to the adjustment terminal TB. A laser shot location LZ11 is set on the adjustment wiring 12-1. Laser shot point L
Z11 is cut off when obtaining the parallel combined resistance of the resistances R12 to R1n.

Here, the resistance values r11 to r1 of the resistors R11 to R1n
The setting value of 1n will be described. Resistance value of resistor R1n r1n
Is set to the maximum impedance and resistance value of the impedance adjustment circuit 11. Resistance value r of resistors R11 to R1n-1
11 to r1n-1, where the resistance value of the resistor R1n is r1n and the number of resistors is N,

[0043]

[Equation 10]

Is set to. That is, the resistance R11-
When the resistance value of R1n-1 is rx,

[0045]

[Equation 11]

Will be determined by Next, the operation of the conventional impedance adjustment circuit 11 will be described. When the impedance adjustment circuit 11 obtains the lowest impedance, no laser shot is performed on any of the laser shot locations LZ11 to LZ1n. By not performing laser shots on any of the laser shot locations LZ11 to LZ1n, none of the adjustment wirings 12-1 to 12-n is cut. Adjustment wiring 12-1 to 12-1
In the state where neither 12-n is disconnected, the adjustment wiring 12-n is connected between the adjustment terminal TA and the adjustment terminal TB, so that the adjustment terminal TA and the adjustment terminal TB are connected. The circuit is short-circuited and the impedance is zero.

Further, in order to obtain the maximum impedance with the impedance adjusting circuit 11, laser shots are made at two laser shot locations LZ1n-1 and LZ1n. Laser shot locations LZ1n-1 and LZ1n
The adjustment wirings 12-n-1 and 12-n are cut by performing laser shots at the two positions. By cutting the adjustment wirings 12-n-1 and 12-n, only the resistor R1n is connected between the adjustment terminal TA and the adjustment terminal TB, and the resistance value r1n of the resistor R1n is the maximum. Will be connected as an impedance.

Further, in the case of obtaining an intermediate impedance, laser shots are performed at one spot only for the laser shot spot LZ1n, at one spot among the laser shot spots LZ1n and LZ11 to LZ1n-1. For example, when laser shot is performed on one of the laser shot locations LZ1n, resistors R11 to R1n are connected in parallel between the adjustment terminal TA and the adjustment terminal TB, so that the adjustment terminal TA and the adjustment terminal TA are adjusted. Resistors R11 to R1n are placed between the terminals TB.
Is connected in parallel. The parallel combined resistance RAB of the resistances R11 to R1n is

[0049]

[Equation 12]

Can be expressed as Here, since the resistors R11 to R1n are set by the above equation (7), the equation (8) is

[0051]

[Equation 13]

It becomes Also, the laser shot location LZ
When laser shots are made at two locations, 1n and LZ11, resistors R12 to R1n are placed between the adjustment terminal TA and the adjustment terminal TB.
Are connected in parallel, a parallel combined resistance RAB of the resistances R12 to R1n is connected between the adjustment terminal TA and the adjustment terminal TB. The parallel combined resistance RAB of the resistances R12 to R1n is

[0053]

[Equation 14]

Can be expressed as Here, since the resistors R11 to R1n are set by the above equation (7), the equation (10) is

[0055]

[Equation 15]

It becomes Also, the laser shot location LZ
When laser shots are made at two locations, 1n and LZ12, a resistance R is placed between the adjustment terminal TA and the adjustment terminal TB.
Since 13 to R1n are connected in parallel, a parallel combined resistance RAB of the resistors R13 to R1n is provided between the adjustment terminal TA and the adjustment terminal TB, and the parallel combined resistance RAB of the resistors R13 to R1n is

[0057]

[Equation 16]

It can be expressed as Here, since the resistors R11 to R1n are set by the above equation (7), the equation (12) is

[0059]

[Equation 17]

It becomes Furthermore, the laser shot location L
When laser shots are made at two points Z1n and LZn-2, the resistors R1n-1 to R1n are connected in parallel between the adjusting terminal TA and the adjusting terminal TB, so that the adjusting terminal TA
A parallel combined resistance RAB of the resistances R1n-2 to R1n is connected between the control terminal TB and the adjustment terminal TB. The parallel combined resistance RAB of the resistors R1n-1 to R1n is

[0061]

[Equation 18]

It can be expressed by Here, since the resistors R11 to R1n are set by the above equation (7), the equation (7) is changed to the equation (1).
Substituting into 4), equation (14) becomes

[0063]

[Formula 19]

It becomes Therefore, the resistance value RAB that can be adjusted by the impedance adjustment circuit 41 is

[0065]

[Equation 20]

It becomes FIG. 2 is a diagram showing the relationship between the cut point and the impedance of the conventional impedance adjustment circuit. In FIG. 2, x indicates cutting. As shown in FIG. 2, when cutting only the laser shot location LZ1n, the combined resistance RAB is (1 / N) × r1n from the equation (9),
When the laser shot locations LZ1n and LZ11 are cut, the combined resistance RAB is (2 / N) × r from the equation (11).
When the laser shot locations LZ1n and LZ12 are cut, the combined resistance RAB is (3) from the equation (13).
/ N) × r1n.

Laser shot points LZ1n and LZ
When Z1n-2 is cut, the combined resistance R
AB becomes {(N-1) / N} × r1n, and when cutting the laser shot locations LZ1n and LZ1n-1, r1n
Becomes As described above, in the impedance adjusting circuit 11 of the present embodiment, the adjustable resistance value can be uniformly adjusted at intervals of (1 / N) × r1n.

FIG. 3 shows a circuit configuration diagram of the second embodiment of the present invention. The impedance adjusting circuit 21 of the present embodiment is shown in FIG.
In the first embodiment, the number N of resistors to be connected is 4, and the maximum resistance value that the impedance adjusting circuit 21 can take is 1
It is set to 40 KΩ.

With respect to the resistance value r11 of the resistor R11 of the impedance adjusting circuit 21, when 4 is substituted into N of the equation (7-1) and 140 KΩ is substituted into r1n,

[0070]

[Equation 21]

It becomes The resistance value r12 of the resistor R12 is
By substituting 4 for N and substituting 140 KΩ for r1n in equation (7-2),

[0072]

[Equation 22]

It becomes The resistance value r13 of the resistor R13 is
Substituting 4 for N and 140 KΩ for r1n in equation (7-3),

[0074]

[Equation 23]

It becomes The resistance value r14 of the resistor R14 is
Since it is set to the maximum resistance r1n, it becomes 140K [Ω]. Here, when laser shot is performed on one of the laser shot locations LZ14, the resistors R11, R12, R13, and R14 are connected in parallel between the adjustment terminal TA and the adjustment terminal TB. Between the terminal TA and the adjusting terminal TB, the parallel combined resistance RAB of the resistances R11, R12, R13 and R13 is provided.
Are connected. The parallel combined resistance RAB of the resistors R11, R12, R13, and R13 is given by

[0076]

[Equation 24]

It becomes Also, the laser shot location LZ
When laser shots are made at 14 and LZ11, a resistance R is placed between the adjustment terminal TA and the adjustment terminal TB.
Adjustment terminal T is used because 12, R13 and R14 are connected in parallel.
A parallel combined resistor RAB of resistors R12, R13, and R14 is connected between A and the adjusting terminal TB. Resistors R12, R13, R14
The parallel combined resistance RAB of

[0078]

[Equation 25]

It becomes Furthermore, the laser shot location L
When laser shots are made at two points Z14 and LZ12, a resistance R is placed between the adjustment terminal TA and the adjustment terminal TB.
Since 13 and R14 are connected in parallel, the parallel combined resistor RAB of the resistors R13 and R14 is connected between the adjusting terminal TA and the adjusting terminal TB. Parallel combined resistance RAB of resistances R13 and R14
Is from equation (15)

[0080]

[Equation 26]

It becomes Therefore, the resistance value RAB that can be adjusted by the impedance adjustment circuit 21 is 0, 35K, 70
It becomes K, 105K, 140K [Ω].

FIG. 4 is a diagram showing the relationship between the cut points and the impedance in the second embodiment of the present invention. In Figure 4 ×
Indicates disconnection. As shown in FIG. 4, in the impedance adjustment circuit 21 of the present embodiment, the adjustable resistance value is (m /
N) r1n (m is a positive integer: N is the number of resistors), and the adjustable resistance value is 0, 35K, 70K, 105K, 14
It becomes 0 K [Ω], and can be adjusted uniformly in units of 35 KΩ.

FIG. 5 shows a circuit configuration diagram of the third embodiment of the present invention. In the impedance adjusting circuit 31 of this embodiment, resistors R31 to R34 are connected in parallel between the adjusting terminal TA and the adjusting terminal TB, and the adjusting wires 32-1 are connected in series to the resistors R31, R32, and R33. 32-2 and 32-3 are provided, and the resistance values of the resistors R31 to R34 are r31, r32, r33, r34.
Is set based on the equation (7) of the first embodiment. Here, N = 4, r34 = 140 K [Ω], and the resistance value r31
Is 420K [Ω], r32 is 210K [Ω], and r33 is 70
It is assumed that K [Ω] and r34 are set to 140K [Ω].

A shorting wiring 32-4 is connected between the adjusting terminal TA and the adjusting terminal TB. A laser shot location LZ34 is set on the short-circuit wiring 32-4. The laser shot location LZ34 is an adjustment terminal T
The impedance is cut off except when the impedance between A and the adjustment terminal TB is set to 0, that is, in the short-circuited state.

The resistor R34 is connected between the adjusting terminal TA and the adjusting terminal TB, and is connected to the adjusting terminal TA and the adjusting terminal T.
The maximum resistance value r with B is set. Resistance R
33 has an adjustment terminal T through one end of the adjustment wiring 32-3.
It is connected to A and the other end is directly connected to the adjustment terminal TB. A laser shot portion L is provided on the adjustment wiring 32-3.
Z33 is provided.

The resistor R32 has one end for the adjustment wiring 32.
-2 is connected to the adjustment terminal TA, and the other end is directly connected to the adjustment terminal TB. The adjustment wiring 32-2 includes
A laser shot location LZ32 is provided. Resistance R
31 has an adjustment terminal T through one end of the adjustment wiring 32-1.
It is connected to A and the other end is directly connected to the adjustment terminal TB. The laser shot location L is provided on the adjustment wiring 32-1.
Z31 is provided.

Next, the operation of the impedance adjusting circuit 31 of this embodiment will be described. When the impedance adjustment circuit 31 obtains the lowest impedance, no laser shot is performed on any of the laser shot locations LZ31, LZ32, LZ33, and LZ34. By not performing laser shot on any of the laser shot locations LZ31, LZ32, LZ33, LZ34, the adjustment wiring 32-1
None of the 32-2, 32-3, and 32-4 are disconnected. Adjustment wiring 32-1, 32-2, 32-
In the state where neither of the terminals 3 and 32-4 is cut, the adjustment wiring 32- is provided between the adjustment terminal TA and the adjustment terminal TB.
Since 4 is connected, adjustment terminal TA and adjustment terminal TB
Is short-circuited, and the impedance is zero.

Further, when the maximum impedance is obtained by the impedance adjusting circuit 31, laser shots are performed on all of the laser shot locations LZ31, LZ32, LZ33, LZ34. Laser shot points LZ31, LZ32,
Adjustment wirings 32-1, 32-2, 32-3, 32-- by performing laser shots on all LZ33, LZ34
4 is cut. Adjustment wiring 32-1, 32-2, 32
-3 and 32-4 are disconnected so that only the resistor R34 is connected between the adjusting terminal TA and the adjusting terminal TB, and the resistance value r of the resistor R34 is connected as the maximum impedance. Become.

Further, in the case of obtaining an intermediate impedance, laser shot points LZ31, LZ32, LZ33,
Laser shot is selectively performed on LZ34. For example, when laser shot is performed on one of the laser shot locations LZ34, resistors R31, R32, R33, and R34 are connected in parallel between the adjustment terminal TA and the adjustment terminal TB. A parallel combined resistor RAB of resistors R31, R32, R33 and R34 is connected between TA and the adjustment terminal TB. The parallel combined resistance RAB of the resistors R31, R32, R33, and R34 is

[0090]

[Equation 27]

It becomes Also, the laser shot location LZ
When laser shots are made at two points of 33 and LZ34, a resistance R is placed between the adjustment terminal TA and the adjustment terminal TB.
Since 31, R32 and R34 are connected in parallel, the adjustment terminal T
A parallel combined resistor RAB of resistors R31, R32, and R34 is connected between A and the adjustment terminal TB. Resistors R31, R32, R34
The parallel combined resistance RAB of

[0092]

[Equation 28]

It becomes Furthermore, the laser shot location L
When laser shots are made at three points Z32, LZ33, and LZ34, the resistors R31 and R34 are connected in parallel between the adjusting terminal TA and the adjusting terminal TB, so that the adjusting terminal TA and the adjusting terminal TB are provided. A parallel combined resistance RAB of the resistances R31 and R34 is connected between and. Resistor R31, R34 parallel combined resistance R
AB is

[0094]

[Equation 29]

It becomes Furthermore, the laser shot location L
When laser shots are made at four points of Z31, LZ32, LZ33, and LZ34, only the resistor R34 is connected between the adjustment terminal TA and the adjustment terminal TB, so that the adjustment terminal TA and the adjustment terminal TA are adjusted. The resistance value of the resistor R34 is 140K [Ω] between the terminal TB and the terminal TB.

FIG. 6 is a diagram showing the relationship between the cut points and the impedance in the second embodiment of the present invention. In Figure 6 ×
Indicates disconnection. As shown in FIG. 6, in the impedance adjustment circuit 31 of the present embodiment, the adjustable resistance value is (m /
N) r1n (m is a positive integer: N is the number of resistors), and the adjustable resistance value is 0, 35K, 70K, 105K, 14
It becomes 0 K [Ω], and can be adjusted uniformly in units of 35 KΩ.

[0097]

As described above, according to the present invention, when the maximum resistance value that can take the resistance value of N resistances is rmax, the resistance value of one resistance Rn among the N resistances is rma
x and set the resistance value rx of the other (N-1) resistors R1 to Rn-1 to

[0098]

[Equation 30]

It is possible to adjust the resistance value of the adjustment terminal with a constant difference by setting to (4) and selectively disconnecting the resistance.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a cut portion and impedance according to the first embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of a second embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a cut portion and impedance according to a second embodiment of the present invention.

FIG. 5 is a circuit configuration diagram of a third embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a cut portion and impedance according to a third embodiment of the present invention.

FIG. 7 is a circuit configuration diagram of an example of a conventional impedance adjustment circuit.

FIG. 8 is a diagram showing a relationship between a cut point and an impedance in an example of a conventional impedance adjustment circuit.

[Explanation of symbols]

1, 11, 21 Impedance adjusting circuits R11 to R14, R21 to R24, R31 to R3n Resistors LZ11 to LZ14, LZ21 to LZ24, LZ31 to LZ3n Laser shot locations

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-13686 (JP, A) JP-A-5-121550 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/82 H01L 21/822 H01L 27/04

Claims (5)

(57) [Claims] 1. An impedance adjusting circuit in which N resistors are connected in parallel between the adjusting terminals, and the impedance between the adjusting terminals is adjusted by disconnecting the connection of the N resistors to the adjusting terminal, An impedance adjustment circuit, wherein the resistance values of the N resistors are set so that the resistance values of the adjustment terminals can be adjusted with a constant difference. 2. When the maximum possible resistance value is rmax, one resistance Rn of the N resistances R1 to Rn is set to the maximum resistance value rmax, and the remaining (N-1) resistances are set. R
The resistance value rx of 1 to Rn-1 is given by The impedance adjustment circuit according to claim 1, wherein 3. The N resistors connect the resistors having the resistance value rmax set between the adjustment terminals, and disconnect the other resistors from the resistors having the resistance value rmax set in descending order of the resistance value. The impedance circuit according to claim 2, wherein the impedance circuit is sequentially connected to one end of the resistor in the preceding stage via a possible wiring. 4. The impedance adjustment circuit according to claim 2, wherein the N resistors are connected in parallel between the adjustment terminals via a disconnectable wiring. 5. A short circuit between the adjusting terminals can be shorted by a disconnectable wiring.
The impedance adjustment circuit according to any one of 1.