JPS60164269A - semiconductor equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a semiconductor device suitable for monitoring voltage inside an integrated circuit.

[Technical background of the invention and its problems]

To monitor voltages inside an integrated circuit, it is possible to attach pads directly to internal nodes. However, in this case, when a measuring instrument is applied to this /4' node, a capacitance greater than the loPF of the measuring instrument is added to the internal nodes of the integrated circuit. Therefore, the signal delay of the internal mate becomes extremely large, making accurate measurement impossible. This is because the canonical capacitance of a normal internal node is several tens of fF. Therefore, one stage of transistors as shown in Figure 1 is used. In the figure, 1 is an integrated circuit, 2 is its internal node, and 3 is M
OS transistor, 4 is a node, 5 is a voltage measuring needle, 6 is a node, and 7 is a resistor. This one is pad 4
Even if a capacitance of 10 PF or more of the measuring instrument is added to the internal node 2, only the f-) capacitance of the transistor 3 is connected to the internal node 2, so the signal delay at the internal node will change drastically due to the measurement. It never gets put away.

When measuring the voltage at the internal node 5 using the monitor transistor 3, the needle 5 is brought into contact with the node 4, the resistor 7 is connected between it and the power supply, and the voltage at the node 6 is measured. However, since the voltage at node 6 is not equal to the voltage at node 5, the internal voltage at node 2 must be calculated backwards from the voltage at node 6 by taking into account the characteristics of transistor 3, which is very troublesome. Also, since the characteristics of transistor 3 itself cannot be measured, the characteristics of transistor 3 are estimated from the characteristics of another transistor made in a different location.
There were also inaccuracies. This is because if the locations are far apart, there will be variations in the threshold voltage, mobility, etc. of the transistors.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a semiconductor device that allows the internal voltage of an integrated circuit, which has conventionally been complicated and inaccurate, to be easily and accurately determined.

[Summary of the invention]

In the present invention, a Gertage 7 Olower (voltage tracking circuit) is configured by a differential amplifier with a negative input and an output connected.
1. The feature is that this output is connected to a metal pad,
This makes it possible to easily measure the internal voltage of an integrated circuit without having to calibrate the transistors unlike in the past.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a configuration diagram of the same embodiment, but since this is an example in which it corresponds to that in FIG. Explain the point.

As shown in the figure, the positive input of the differential amplifier 8 is connected to the integrated circuit 1.
The negative input is connected to the internal node 2 of the integrated circuit 1, and the negative input is connected to the output, which is connected to the internal node 2 of the chip
Connected to Tudo 4. In the figure, numeral 9 is a measuring device for detecting the voltage of the node 4.

Here, the amplification degree of the differential amplifier 8 is set to A, and the input voltage is set to A.

If the output voltages are vin and Vout, respectively, A
(Min−Vout)=Vout”=(1
). If the amplification degree A is made sufficiently large in equation (2), Vout = Vin, and the output voltage V ou
By monitoring t, it can be seen that it is equal to the input voltage Vin. This circuit is called Giltage 7 Orowa. That is, the trouble associated with transistor calibration and the inaccuracy of measurement results due to estimation of transistor characteristics, which were conventionally necessary, are eliminated.

Did the third meat use a differential amplifier? This is an example of Lutege 7 Orowa. In this example, the drive transistor is an N-channel type and the load is a P-channel type, but conversely, a configuration in which the drive transistor is a P-channel type and the load is an N-channel type is also conceivable. A first stage differential amplifier made up of transistors 10-13 and a second stage differential amplifier made up of transistors 14-17 are connected in series.

The darts of the load transistors 70.11 are connected in common,
Its potential is the same as that of the drain of the load transistor 11, and is of a current mirror type. The amplification degree of the current mirror type is large and is useful for increasing A in equation (2). fl, 7' 42 stages must be connected in series to obtain sufficient amplification A. Another reason for using a 1.2-stage differential amplifier is to obtain sufficient drive capability, and to avoid the large capacitance of the measuring instrument system. (for example, 10PF), the final stage transistors 16 and 17 need to have a large channel width, but if such a large transistor is connected directly to an internal node, it will still cause disturbance to the internal circuit. big. The fraction shown in FIG. 3(b) is W/L (W is the channel width and L is the channel length).

A current limiting element may be inserted in series with the driving transistors 16 and 17, like the transistor I8 in FIG. 3(b). Here, the current is limited by the transistor 18, but a resistor may also be used. The measured DC (direct current) and AC (alternating current) characteristics of this circuit are shown in FIGS. 4 and 5, respectively. DC,
For both AC, the input voltage -vin and the output voltage Vout are equal.

FIG. 6 shows a modification of the invention. Here, a current mirror is not used for the second-stage differential amplifier, but a differential amplifier with a simple load (independent load type) is used. In the case of a current mirror, the output increases only to a voltage lower than the threshold voltage \VTHP of the P-channel transistor and the power supply voltage VDD, but in the configuration shown in FIG. 6, the output increases to nearly VDD.

Note that the present invention is not limited to the above explanation, and can be applied in various ways. For example, the metal pad 4 may be used in the manufacturing stage, and when the product is manufactured, a protective layer may be placed over the pad. Further, in order to reduce the power consumption of the integrated circuit power supply, a separate power supply may be provided, and the power supply for the differential amplifier may be supplied from the outside independently of the power supply used in the integrated circuit main body. .

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to easily and accurately measure the internal voltage without having to calibrate the comparison sensor transistor in the past. Furthermore, since it has a two-stage differential amplifier configuration, it is possible to measure the internal voltage without introducing disturbances caused by the measuring device inside.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing a conventional internal voltage monitor circuit;
The figure is a block diagram of an embodiment of the present invention, FIG.
), Figure 4 (al is the measurement circuit diagram of the DC actual measurement characteristics, the same figure (bl or dl is the actual measurement characteristic diagram, Figure 5 is the AC actual measurement characteristic diagram, Figure 6 is Figure 3) (It is a circuit diagram showing a modification of bJ. 1... Integrated circuit, 2.°° internal node, 4...] Arm rad 8... Difference wJ amplifier. Fig. 1 7 3rdry1 (a) (b) Figure 5 ACCharacteristics of Volt
age FollowerVoc [v] 6th Ding DDvDD

Claims (1)

[Claims] +1) A semiconductor characterized in that it has a differential amplifier whose glass input is connected to an internal node of an integrated circuit and whose negative input is connected to an output, and a pad-like metal is arranged at the output of the differential amplifier. Device. (2) The semiconductor device according to claim 1, wherein the differential amplifier is a two-stage current mirror type amplifier. (3) The first stage of the differential amplifier is composed of a current mirror type differential amplifier, and the second stage is composed of an independent load type differential amplifier. The semiconductor device according to claim 1, characterized in that differential amplifiers are connected in series. (4) The semiconductor device according to claim 1, wherein a power source for the differential amplifier is supplied from outside independently of a power source used in the integrated circuit.