# US 10,481,185 B2 · Semiconductor device, semiconductor system, and control method of semiconductor device to monitor a power supply voltage

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- Number: US 10,481,185 B2
- Document ID: US10481185B2
- Status: Granted
- Kind: B2
- Application number: 15/704,270
- Filed: 2017-09-14
- Published: 2018-04-05
- Granted: 2019-11-19
- Earliest claimed: 2016-09-30
- Assignees: Renesas Electronics Corporation
- Applicants: Renesas Electronics Corporation
- Inventors: Kazuki Fukuoka; Toshifumi Uemura; Yuko Kitaji; Yosuke Okazaki; Akira Murayama
- Web page: https://patentgrep.com/patent/US10481185B2

## CPC

- G01R 19/16552: {in I.C. power supplies}
- G01R 31/2851: {Testing of integrated circuits [IC] (G01R31/317 takes precedence; testing individual devices G01R31/26; testing printed circuits G01R31/2801)}
- G01R 31/31703: {Comparison aspects, e.g. signature analysis, comparators (concerning scan tests G01R31/318566; concerning testers G01R31/3193)}
- G01R 31/3177: Testing of logic operation, e.g. by logic analysers
- G01R 31/318328: {for delay tests}
- G01R 31/31932: {Comparators}
- G01R 31/31937: {Timing aspects, e.g. measuring propagation delay (G01R31/3191 and G01R31/31922 take precedence; marginal testing G06F11/24)}
- G06F 1/24: Resetting means
- G06F 1/28: Supervision thereof, e.g. detecting power-supply failure by out of limits supervision
- H03K 3/0315: {Ring oscillators}
- H03K 5/133: using a chain of active delay devices
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)

## Abstract

A semiconductor device, a semiconductor system, and a control method of a semiconductor device are capable of accurately monitoring the lowest operating voltage of a circuit to be monitored. According to one embodiment, a monitor unit of a semiconductor system includes a voltage monitor that is driven by a second power supply voltage different from a first power supply voltage supplied to an internal circuit that is a circuit to be monitored and monitors the first power supply voltage, and a delay monitor that is driven by the first power supply voltage and monitors the signal propagation period of time of a critical path in the internal circuit.

## Claims

### Claim 1

A semiconductor device comprising:
a voltage monitor that is driven by a second power supply voltage different from a first power supply voltage supplied to a circuit to be monitored and monitors the first power supply voltage; and
a delay monitor that is driven by the first power supply voltage and monitors the signal propagation period of time of a critical path in the circuit to be monitored.

### Claim 2 (depends on 1)

The semiconductor device according to claim 1,
wherein the delay monitor includes a delay information generation unit driven by the first power supply voltage, and monitors the signal propagation period of time of the critical path in the circuit to be monitored by monitoring delay information generated by the delay information generation unit.

### Claim 3 (depends on 2)

The semiconductor device according to claim 2,
wherein the delay information generation unit has a first ring oscillator driven by the first power supply voltage, and
wherein the delay monitor further includes:
a first counter that counts the number of times of oscillation per predetermined period of oscillation signals output from the first ring oscillator;
a first comparison circuit that compares the count value of the first counter with a first threshold value; and
a first determination circuit that determines whether or not the signal propagation period of time of the critical path in the circuit to be monitored falls within an allowable range on the basis of the comparison result by the first comparison circuit.

### Claim 4 (depends on 3)

The semiconductor device according to claim 3,
wherein the first determination circuit determines that the signal propagation period of time of the critical path in the circuit to be monitored falls within the allowable range in the case where the count value of the first counter is larger than the first threshold value, and determines that the signal propagation period of time of the critical path in the circuit to be monitored is out of the allowable range in the case where the count value of the first counter is equal to or smaller than the first threshold value.

### Claim 5 (depends on 4)

The semiconductor device according to claim 4,
wherein the first determination circuit determines that the signal propagation period of time of the critical path in the circuit to be monitored is out of the allowable range in the case where the number of times that the count value of the first counter becomes equal to or smaller than the first threshold value reaches the predetermined number of times.

### Claim 6 (depends on 3)

The semiconductor device according to claim 3,
wherein the first ring oscillator has a plurality of NOR circuits and a plurality of NAND circuits that are alternately provided in a ring shape, and
wherein the drive capability of each NOR circuit is larger than that of each NAND circuit.

### Claim 7 (depends on 6)

The semiconductor device according to claim 6,
wherein the first ring oscillator further includes:
a diode provided between a high potential-side voltage terminal of either one of the NOR circuits and the NAND circuits and a power supply voltage terminal to which the first power supply voltage is supplied; and
a level shifter that shifts the voltage range of an output signal from the either one to the ranges of the first power supply voltage and the ground voltage.

### Claim 8 (depends on 6)

The semiconductor device according to claim 6,
wherein the first ring oscillator further includes a resistance element provided on a ring formed by the NOR circuits and the NAND circuits.

### Claim 9 (depends on 3)

The semiconductor device according to claim 3,
wherein the delay information generation unit further has a second ring oscillator that is driven by the first power supply voltage and is different in temperature dependency from the first ring oscillator, and
wherein the delay monitor further includes:
a second counter that counts the number of times of oscillation per predetermined period of oscillation signals output from the second ring oscillator;
a second comparison circuit that compares the count value of the second counter with a second threshold value; and
a second determination circuit that determines whether or not the signal propagation period of time of the critical path in the circuit to be monitored falls within the allowable range on the basis of the comparison result by the second comparison circuit.

### Claim 10 (depends on 9)

The semiconductor device according to claim 9,
wherein the second ring oscillator has temperature dependency opposite to that of the first ring oscillator.

### Claim 11 (depends on 2)

The semiconductor device according to claim 2,
wherein the delay information generation unit has a first signal propagation route that is driven by the first power supply voltage and outputs an output signal in accordance with an input signal, and
wherein the delay monitor further includes:
a first conversion circuit that converts into a digital signal a period of time required from the time an input signal is input to the first signal propagation route to the time an output signal is output;
a first comparison circuit that compares the comparison result by the first conversion circuit with a first threshold value; and
a first determination circuit that determines whether or not the signal propagation period of time of the critical path in the circuit to be monitored falls within the allowable on the basis of the comparison result by the first comparison circuit.

### Claim 12 (depends on 1)

The semiconductor device according to claim 1,
wherein the delay monitor is configured to operate even in the case where it is determined by the voltage monitor that the first power supply voltage has reached the lowest operation guarantee voltage of the circuit to be monitored.

### Claim 13 (depends on 1)

A semiconductor system comprising:
semiconductor device according to claim 1; and
a circuit to be monitored by the semiconductor device.

### Claim 14

A control method of a semiconductor device, comprising:
monitoring a first power supply voltage using a voltage monitor driven by a second power supply voltage that is different from the first power supply voltage supplied to a circuit to be monitored; and
monitoring the signal propagation period of time of a critical path in the circuit to be monitored using a delay monitor driven by the first power supply voltage.

### Claim 15 (depends on 14)

The control method of the semiconductor device according to claim 14,
wherein the signal propagation period of time of the critical path in the circuit to be monitored is monitored by monitoring delay information generated by a delay information generation unit driven by the first power supply voltage.