# US 2021/0242838 A1 · Amplifier

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2021/0242838 A1
- Document ID: US20210242838A1
- Status: Published application
- Kind: A1
- Application number: 17/049,901
- Filed: 2019-02-08
- Published: 2021-08-05
- Earliest claimed: 2018-05-11
- Assignees: Sony Semiconductor Solutions Corporation
- Applicants: Sony Semiconductor Solutions Corporation
- Inventors: KAZUMASA NISHIMURA; MASAHIRO ICHIHASHI; MASAYUKI KATAKURA; KENYA KONDOU; TETSUYA TASHIRO; BOYANG HAO; KOUZI TSUKAMOTO
- Web page: https://patentgrep.com/patent/US20210242838A1

## CPC

- H03F 1/223: {with MOSFET's}
- H03F 3/211: {using a combination of several amplifiers (H03F3/60 takes precedence)}
- H03F 3/187: in integrated circuits
- H03F 3/347: in integrated circuits
- H04N 25/617: for reducing electromagnetic interference, e.g. clocking noise
- H04N 25/618: for random or high-frequency noise
- H04N 25/78: Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters
- H03F 1/301: {in MOSFET amplifiers (H03F1/303, H03F1/305, H03F1/308 take precedence)}
- H03F 1/302: {in bipolar transistor amplifiers (H03F1/303, H03F1/305, H03F1/307 take precedence)}
- H03F 3/16: with field-effect devices
- H03F 3/72: Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
- H03F 2200/18: the bias of the gate of a FET being controlled by a control signal
- H03F 2200/429: Two or more amplifiers or one amplifier with filters for different frequency bands are coupled in parallel at the input or output
- H03F 2200/432: Two or more amplifiers of different type are coupled in parallel at the input or output, e.g. a class D and a linear amplifier, a class B and a class A amplifier
- H03F: AMPLIFIERS
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

To easily adjust a gain of an amplifier. An applied input signal is input to a gate terminal of a first transistor, and a current depending on the applied input signal flows through the first transistor. A load section is connected to a drain terminal of the first transistor. A gate terminal of a second transistor is connected to the load section, and a current depending on a change in a voltage of the drain terminal of the first transistor flows through the second transistor. A source terminal of the first transistor and a drain terminal of the second transistor are connected in common to a first resistance, and the current from the first transistor and the current from the second transistor flow through the first resistance. A third transistor supplies a current approximately equal to the current of the second transistor. The current supplied by the third transistor is output from an output end.

## Claims

### Claim 1

An amplifier, comprising:
an input end to which an input signal is applied;
a low-frequency amplifier circuit that includes
a first transistor having a gate terminal to which the applied input signal is input, the first transistor being a transistor through which a current depending on the applied input signal flows,
a load section that is connected to a drain terminal of the first transistor,
a second transistor of which a gate terminal is connected to the load section, the second transistor being a transistor through which a current depending on a change in a voltage of the drain terminal of the first transistor flows,
a first resistance to which a source terminal of the first transistor and a drain terminal of the second transistor are connected in common, the first resistance being a resistance through which the current from the first transistor and the current from the second transistor flow, and
a third transistor that supplies a current approximately equal to the current of the second transistor;
a high-frequency amplifier circuit that includes
a constant current circuit,
a fourth transistor that is connected in series to the input end and the constant current circuit, the fourth transistor being a transistor through which a bias current from the constant current circuit flows,
a first capacitor that is connected in parallel to the constant current circuit and causes an alternating current signal from among the input signal to flow into the fourth transistor, and
a fifth transistor that forms a current mirror circuit with the fourth transistor and supplies a current depending on the current flowing through the fourth transistor; and
an output end from which the current supplied by the third transistor and the current supplied by the fifth transistor are output.

### Claim 2 (depends on 1)

The amplifier according to claim 1, further comprising
a second resistance that is connected to the output end and converts the output current into voltage.

### Claim 3 (depends on 1)

The amplifier according to claim 1, wherein
the low-frequency amplifier circuit further includes
a second capacitor that is connected between the input end and the gate terminal of the first transistor, and
a bias circuit that supplies a bias voltage to the gate terminal of the first transistor.

### Claim 4 (depends on 1)

The amplifier according to claim 1, wherein
the load section is formed of a constant current circuit.

### Claim 5 (depends on 1)

The amplifier according to claim 1, wherein
the constant current circuit of the high-frequency amplifier circuit is formed of a current mirror circuit that causes a current depending on the current flowing through the third transistor to flow, and
the third transistor supplies the current to the output end via the high-frequency amplifier circuit.

### Claim 6 (depends on 1)

The amplifier according to claim 1, wherein
the low-frequency amplifier circuit further includes a sixth transistor that is connected to the first transistor in a cascode arrangement.

### Claim 7 (depends on 6)

The amplifier according to claim 6, wherein
the low-frequency amplifier circuit further includes a second constant current circuit that supplies a bias current to the first transistor.