# US 2010/0164590 A1 · Semiconductor integrated circuit

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- Number: US 2010/0164590 A1
- Document ID: US20100164590A1
- Status: Published application
- Kind: A1
- Application number: 12/690,090
- Filed: 2010-01-19
- Published: 2010-07-01
- Earliest claimed: 2006-03-22
- Assignees: Yamaha Corporation
- Inventors: NOBUAKI TSUJI; HIROTAKA KAWAI
- Web page: https://patentgrep.com/patent/US20100164590A1

## CPC

- H03F 3/217: Class D power amplifiers; Switching amplifiers
- H03F: AMPLIFIERS

## Abstract

An N-channel transistor is provided as a switch between a high potential power line and a low potential power line. A high-pass filter is constituted by a capacitor and a resistor. When a voltage between the high potential power line and the low potential power line is started to oscillate by a switching operation, the high-pass filter causes a high-pass component thereof to pass, thereby turning ON the N-channel transistor to reduce a ringing.

## Claims

### Claim at position 1

1-3. (canceled)

### Claim 4

A ringing reduction circuit provided inside a semiconductor integrated circuit that includes an output buffer circuit and an output signal line for transmitting an output signal of the output buffer to a load outside the semiconductor integrated circuit, the ringing reduction circuit comprising:
a switching element inserted between the output signal line and a high-potential power line or a low-potential power line for supplying a power supply voltage to the output buffer circuit; and
a ringing detector that outputs a signal for turning on the switching element when ringing occurs in the output signal and the output signal exceeds a reference level in a positive or negative direction.

### Claim 5 (depends on 4)

The ringing reduction circuit according to claim 4, wherein the ringing detector comprises a comparator for detecting that the output signal exceeds the reference level in the positive or negative direction by comparing a level of the output signal line with a level of the high-potential power line or the low-potential power line.

### Claim 6 (depends on 4)

The ringing reduction circuit according to claim 4, wherein the ringing detector comprises a comparator for detecting that the output signal exceeds the reference level in the positive or negative direction by comparing a level of the output signal line with a level of a power line that is different from the high-potential power line and the low-potential power line.

### Claim 7 (depends on 4)

The ringing reduction circuit according to claim 4, wherein the ringing detector comprises a comparator for detecting that the output signal exceeds the reference level in the positive or negative direction by comparing a level of the high-potential power line or the low-potential power line with a level of a power line that is different from the high-potential power line and the low-potential power line and is not part of a path of a switching current flowing through the output buffer circuit.

### Claim 8 (depends on 4)

The ringing reduction circuit according to claim 4, wherein
the switching element is inserted between the output signal line and the low-potential power line, and
the ringing detector outputs a signal for turning on the switching element when detecting that the output signal exceeds, in the positive direction, the reference level that is a level of the high-potential power line or a level that is more stable than the level of the high-potential power line.

### Claim 9 (depends on 4)

The ringing reduction circuit according to claim 4, wherein
the switching element is inserted between the output signal line and the high-potential power line, and
the ringing detector outputs a signal for turning on the switching element when detecting that the output signal exceeds, in the negative direction, the reference level that is a level of the low-potential power line or a level that is more stable than the level of the low-potential power line.

### Claim 10 (depends on 4)

The ringing reduction circuit according to claim 4, wherein
the switching element comprises a first switching element inserted between the output signal line and the low-potential power line and a second switching element inserted between the output signal line and the high-potential power line; and
the ringing detector comprises a first comparator for outputting a signal for turning on the first switching element when detecting that the output signal exceeds, in the positive direction, a first reference level that is a level of the high-potential power line or a level that is more stable than the level of the high-potential power line and a second comparator for outputting a signal for turning on the second switching element when detecting that the output signal exceeds, in the negative direction, a second reference level that is a level of the low-potential power line or a level that is more stable than the level of the low-potential power line.

### Claim 11

(canceled)