JPS593846B2 - Circuit element trimming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic frequency adjustment device for adjusting circuit elements formed of semiconductor films.

Generally, the capacitance of a crystal oscillator is adjusted by adjusting a trimmer capacitor to a specified capacitance.

However, according to this method, when attempting to miniaturize the circuit configuration by integrating the circuit configuration, the space occupied by the trimmer capacitor is undesirable.

Therefore, when attempts were made to integrate capacitors and adjust their capacitance, conventional methods had the following drawbacks.

In order to adjust the capacitance of an integrated capacitor element, it has been trimmed to a preset value using a laser beam, a drill, or the like.

However, capacitor elements are generally made of thin films, and once trimmed to a negative value, the capacitor element becomes smaller than the specified capacity, and it is difficult to restore it to the specified capacity. .

In view of this, the present invention has been developed to convert the frequency corresponding to the output frequency of the difference between the output of the oscillation circuit to be adjusted and the reference frequency, which changes the output frequency according to the amount of adjustment of the variable frequency adjustment section, into m (n>m
), thereby eliminating the above-mentioned drawbacks of the conventional method.

Hereinafter, an embodiment will be described in which the difference between the output frequency of the oscillation circuit and the reference frequency is converged to 1/2 for adjustment.

1 is the reference frequency f. This is a reference oscillation circuit that generates

Reference numeral 2 denotes a thin film capacitor element formed on a substrate (not shown) or the like, and constitutes a frequency variable adjustment section.

3 is an oscillation circuit to be adjusted, which uses the thin film capacitor element 2 as a load capacitance, and before cutting and trimming the thin film capacitor element 2, it oscillates at a frequency lower than the frequency fo, and when the thin film capacitor element 2 reaches the specified capacity, the frequency increases. It oscillates at fo.

A timing pulse generator 4 generates a timing pulse when the terminal α is at a logical high level.

5 is a detection device, which counts the output pulses of the adjusted oscillation circuit 3 and the reference oscillation circuit 1 every time a timing pulse is generated from the timing pulse generator 4, and then detects the difference in the respective oscillation frequencies. be.

6 is an N-ary (M=2.3...) counting circuit, and when counting N, its output is inverted to a low level.

I is an arithmetic circuit which receives the output of the detection device 5, sequentially adds the difference in the output frequency of the crystal oscillator 1.3, and adds the difference in the output frequency of the crystal oscillator 1.
The total sum added N times is divided by N based on the output of , and the average value of the N times is taken.

8 is a conversion circuit that converts the average value of the difference frequency from the arithmetic circuit I into an analog voltage corresponding to one half of the average value of the difference frequency, and the reference oscillation circuit 1 and the adjusted oscillation circuit 3 from the arithmetic circuit 7. When the average value of the difference in output frequency becomes less than a very small predetermined value, the output voltage drops to a predetermined voltage.

Here, the arithmetic circuit T and the conversion circuit 8 constitute a conversion processing circuit.

Reference numeral 9 denotes a control device, which inverts the output to a low level when the output voltage of the conversion circuit 8 becomes less than a predetermined voltage.

10 is a notification device such as a buzzer, a lamp, etc., and a control device 9
It is activated when the output of the controller becomes low level.

Reference numeral 11 denotes a comparator circuit, which produces an output while there is a difference between the output voltages of the potentiometer 12 and the conversion circuit 8, and the amplifier 1
3 to drive the motor 14.

Reference numeral 15 denotes a laser gun, which is fixed to a rack board 16 at a position facing the thin film capacitor element 2.

The rack board 16 is moved via a gear train (not shown) by the rotation of the motor 14.

17 is a drive device for the laser gun 15, and a comparison circuit 11
One pulse is generated by stopping the output from the laser gun 15, causing the laser gun 15 to emit a laser beam, and as the emission stops, the output terminal is inverted to a high level.

Drive device 17, laser gun 15, rack board 16, motor 14, amplifier 13, potentiometer 12, conversion circuit 8
The comparator circuit 11 constitutes an adjustment device.

18 is a gate circuit, and 19 is a differential shaping circuit that differentiates the rising edge of the pulse.

Potentiometer 12, amplifier 13, motor 14, laser gun 15, rack board 16 and drive device 17 constitute adjustment means.

Timing pulse generator 4, counting circuit 6, drive device 1T
The differential shaping circuit 19 constitutes a readjustment circuit, and the control device 9 and gate circuit 18 constitute an adjustment stop circuit.

Next, the operation will be explained.

Before the thin film capacitor element 2 is trimmed, the adjusted oscillation circuit 3 oscillates at a frequency lower than the specified frequency fo.

Therefore, every time a timing pulse is generated from the timing pulse generator 4, the difference from the oscillation frequency fo of the reference oscillation circuit 1 is detected by the detection device 5, supplied to the arithmetic circuit I, and sequentially added.

When N timing pulses are generated and the frequency difference is detected N times, the output of the counting circuit 6 makes the addition result of the arithmetic circuit 7 1 of N times, and the average of the N times of the frequency difference is The value is calculated.

This is to compensate for the case where the adjusted oscillation circuit 3 becomes temporarily unstable during trimming and the frequency difference deviates.

Now, the output level of the gate circuit 18 is inverted by the output of the counting circuit 6, and the timing pulse from the timing pulse generator 4 is stopped.

The average value of the frequency difference from the calculation circuit 7 is calculated by the conversion circuit 8.
is converted into an analog voltage corresponding to one-half of the voltage, and this voltage is further compared with the output voltage of the potentiometer 12 by a comparator circuit 11.

The motor 14 is driven by the output of the comparison circuit 11 via the amplifier 13, and the rack board 16 is moved to move the laser gun 1.
5 moves by a length that reduces the frequency difference to half, the output voltage of the potentiometer 12 matches the output voltage of the conversion circuit 8, and the output of the comparison circuit 11 stops.

Therefore, the motor 14 stops and the drive circuit 17
One pulse is generated and a laser beam is generated from the laser gun 15 to trim the thin film capacitor element 2.

Therefore, the difference between the output frequencies of the adjusted oscillation circuit 3 and the reference oscillation circuit 1 becomes one-half of the state before trimming.

On the other hand, as the trimming is completed, the level of the terminal of the drive circuit 17 is inverted, and the counting circuit 6 is reset by its differential output.

Therefore, the level of the output of the gate circuit 18 is inverted again, a timing pulse is generated from the timing pulse generator 4, and the same operation as described above is repeated.

In this way, the thin film capacitor element 2 is gradually trimmed,
With each trimming, the difference between the oscillation frequencies of the adjusted oscillation circuit 3 and the reference oscillation circuit 1 is reduced by half, and the oscillation frequency of the adjusted oscillation circuit 3 gradually approaches the frequency fo.

When the frequency difference becomes less than a predetermined value, the output voltage of the conversion circuit 8 becomes less than the predetermined voltage, and the output level of the control device 9 is inverted.

Therefore, the output level of the gate circuit 18 is inverted, the timing pulse from the timing pulse generator 4 is stopped, and trimming is completed.

On the other hand, the reversal of the output level of the control device 9 activates the notification device 10 to notify the completion of trimming.

As described above, the thin film capacitor element 2 is trimmed so that the difference in oscillation frequency between the adjusted oscillation circuit 3 and the reference oscillation circuit 1 converges to one-half, and this process is repeated until the thin film capacitor element 2 is trimmed to the specified length. Since the thin film capacitor element 2 is not trimmed to be shorter than the specified length, the capacitance can be adjusted reliably and with high precision.

By the way, in the above embodiment, the case where the adjustment is performed by converging the difference in oscillation frequency between the oscillation circuit to be adjusted 3 and the reference oscillation circuit 1 to one-half has been explained, but the present invention is not limited to this. What is necessary is to converge to m (n>m).

Note that in the above embodiment, the conversion circuit 8 converts the frequency of the difference between the adjusted oscillation circuit 3 and the reference oscillation circuit 1 into half of the difference in frequency.
Although the adjustment is made by converting the voltage to a voltage equivalent to
It may be set to 1/1.

Furthermore, the gear train that transmits the rotation of the motor 14 to the rack board 16 may be appropriately set to move the laser gun 15 by a length that changes the frequency of the difference by half.

Furthermore, in the above embodiment, a case was explained in which a thin film capacitor element was used as the frequency variable adjustment section, but the invention is not limited to this, and the present invention is not limited to this. It may also be used for trimming.

In this case, an electric circuit such as a CR oscillator having a resistive element as a component is used in place of the illustrated oscillation circuit 3 to be adjusted, and adjustment is performed in exactly the same manner as in the above embodiment.

Further, the adjustment of the thin film resistive element is not limited to the trimming described above.

For example, a conductive thin piece may be slid over the thin film resistive element and bonded to an appropriate position.

Further, in the above embodiment, trimming was performed using a laser gun, but the trimming is not limited to this, and a drill, cutter, etc. may also be used.

Further, in the above embodiment, the laser gun is moved to select the trimming position of the thin film capacitor element, but the present invention is not limited to this, and the laser gun may be fixed while the thin film capacitor element is moved.

Further, in the above embodiment, the control device 9 and the gate circuit 18
Although the timing pulse generator 4 is stopped by the output of the controller 9 to end the trimming, trimming may be stopped by the output of the control device 9. The circuit 8 etc. may be stopped or the power source may be cut off.

As detailed above, according to the present invention, the frequency corresponding to the difference between the output of the oscillation circuit to be adjusted and the reference frequency, which changes the output frequency according to the adjustment amount of the frequency variable adjustment section, is divided into m/n. Since the part to be adjusted is gradually adjusted so as to change the amount, the part to be adjusted can be adjusted without exceeding a specified amount, and the adjustment can be performed reliably and with high precision.

[Brief explanation of drawings]

The drawing is an electrical circuit diagram showing an embodiment of the present invention. 2... Part to be adjusted, 3... Oscillation circuit to be adjusted, 5... Detection device, 9... Control device, 11... Comparison circuit, 12...Potentiometer, 13...Amplifier, 14...
・Motor, 15... Laser gun, 16...
...Rack board, 18...Gate circuit.

Claims (1)

[Claims] 1. A reference oscillation circuit that generates a reference frequency, an adjusted oscillation circuit that generates a frequency asymptotic to the reference frequency according to the adjustment of the variable frequency adjustment section, a timing pulse generation circuit that generates a timing pulse, and a timing pulse generation circuit that generates a timing pulse. A detection device that synchronously generates a frequency difference between the output frequency of the oscillation circuit to be adjusted and the reference frequency, and an operation that converts the result of addition of the difference frequency k (positive integer) times to 1/2. The output of the circuit and the arithmetic circuit is divided into n parts m(n)m
, n and m are positive integers), an adjustment device that adjusts the frequency variable adjustment section according to the output of the conversion circuit to change the output frequency of the oscillation circuit to be adjusted, and an adjustment output of the adjustment device. means for causing the arithmetic circuit to perform arithmetic processing again in response; a control device that stops the output pulse of the timing pulse generation circuit when the output of the conversion circuit reaches a specific value; and a control device that terminates the adjustment upon receiving the output of the control device. A circuit element trimming device comprising a notification device for notifying.