US-12627261-B2 - Amplifying circuit

US12627261B2US 12627261 B2US12627261 B2US 12627261B2US-12627261-B2

Abstract

An amplifying circuit includes a first transistor, a second transistor, and a switching circuit. A control terminal of the first transistor is coupled to an input terminal of the amplifying circuit, and a first terminal of the first transistor is coupled to a first reference end. The input terminal of the amplifying circuit receives a first radio frequency (RF) signal. A first terminal of the second transistor is coupled to a second terminal of the first transistor, and a second terminal of the second transistor is coupled to an output terminal of the amplifying circuit. The output terminal of the amplifying circuit outputs an amplified signal. The first transistor amplifies the first RF signal to generate a second RF signal. The switching circuit performs a switching operation to transmit the second RF signal to one of the first terminal and the control terminal of the second transistor.

Inventors

Chih-Sheng Chen
Yu-Hsuan Chao

Assignees

RICHWAVE TECHNOLOGY CORP.

Dates

Publication Date: 20260512
Application Date: 20221214
Priority Date: 20221202

Claims (19)

1 . An amplifying circuit comprising: a first transistor having a first terminal, a second terminal, and a control terminal, the control terminal of the first transistor being coupled to an input terminal of the amplifying circuit, and the first terminal of the first transistor being coupled to a first reference end, wherein the input terminal of the amplifying circuit is configured to receive a first radio frequency signal; a second transistor having a first terminal, a second terminal, and a control terminal, the first terminal of the second transistor being coupled to the second terminal of the first transistor, and the second terminal of the second transistor being coupled to an output terminal of the amplifying circuit, wherein the output terminal of the amplifying circuit is configured to output an amplified signal; a switching circuit coupled to the second terminal of the first transistor, the first terminal of the second transistor, and the control terminal of the second transistor, wherein the first transistor amplifies the first radio frequency signal to generate a second radio frequency signal at the second terminal of the first transistor, the switching circuit performs a switching operation to transmit the second radio frequency signal to one of the first terminal of the second transistor and the control terminal of the second transistor, wherein the switching circuit comprises: a first inductor coupled between the second terminal of the first transistor and the first terminal of the second transistor; a first switch coupled between the second terminal of the first transistor and the control terminal of the second transistor; and a second switch coupled in parallel with the first inductor.
2 . The amplifying circuit according to claim 1 , wherein the switching circuit further comprises: a first capacitor; and a third switch coupled in series with the first capacitor between the first terminal of the second transistor and a second reference end.
3 . The amplifying circuit according to claim 2 , wherein the switching circuit further comprises: a second capacitor coupled in series with the first switch between the second terminal of the first transistor and the control terminal of the second transistor.
4 . The amplifying circuit according to claim 3 , wherein the first switch and the second switch are respectively controlled by a first control signal and a second control signal to be turned on or turned off, wherein when the first switch is off and the second switch is on, the second radio frequency signal is transmitted through the second switch to the first terminal of the second transistor, and when the first switch is on and the second switch is off, the second radio frequency signal is transmitted through the first switch to the control terminal of the second transistor.
5 . The amplifying circuit according to claim 1 , wherein the first transistor and the second transistor share a direct current.
6 . The amplifying circuit according to claim 4 , wherein when the second radio frequency signal is transmitted to the control terminal of the second transistor, the first inductor presents a high impedance state for the second radio frequency signal, the first capacitor presents a low impedance state for the second radio frequency signal, and the second capacitor presents a low impedance state for the second radio frequency signal.
7 . The amplifying circuit according to claim 6 , wherein when the first switch is on, the first switch presents a low impedance state for the second radio frequency signal; when the second switch is on, the second switch presents a low impedance state for the second radio frequency signal; and when the third switch is on, the third switch presents a low impedance state for the second radio frequency signal.
8 . The amplifying circuit according to claim 4 , wherein the third switch is controlled by a third control signal, the third switch is turned on or turned off according to the third control signal, and when the first switch is turned on, the third switch is turned on, such that the second transistor is coupled to the second reference end via the first capacitor.
9 . The amplifying circuit according to claim 8 , wherein the switching circuit further comprises: a fourth switch, wherein the first terminal of the second transistor, the third switch, the first capacitor, and the second reference end are sequentially coupled, the third switch and the first capacitor are coupled to a node, and the fourth switch is coupled between the node and the control terminal of the second transistor.
10 . The amplifying circuit according to claim 9 , wherein the fourth switch is controlled by a fourth control signal, the fourth switch is turned on or turned off according to the fourth control signal, and wherein when the second switch is turned on, the fourth switch is turned on, such that the control terminal of the second transistor is coupled to the second reference end via the first capacitor.
11 . The amplifying circuit according to claim 4 , wherein the switching circuit further comprises: a first operation resistor coupled between a first terminal and a second terminal of the first switch; and a second operation resistor coupled between a first terminal and a second terminal of the second switch.
12 . An amplifying circuit comprising: a first transistor having a first terminal, a second terminal, and a control terminal, the control terminal of the first transistor being coupled to an input terminal of the amplifying circuit, and the first terminal of the first transistor being coupled to a first reference end, wherein the input terminal of the amplifying circuit is configured to receive a first radio frequency signal; a second transistor having a first terminal, a second terminal, and a control terminal, the first terminal of the second transistor being coupled to the second terminal of the first transistor, and the second terminal of the second transistor being coupled to an output terminal of the amplifying circuit, wherein the output terminal of the amplifying circuit is configured to output an amplified signal; a switching circuit coupled to the second terminal of the first transistor, the first terminal of the second transistor, and the control terminal of the second transistor, wherein the first transistor amplifies the first radio frequency signal to generate a second radio frequency signal at the second terminal of the first transistor, the switching circuit performs a switching operation to transmit the second radio frequency signal to one of the first terminal of the second transistor and the control terminal of the second transistor, the amplifying circuit further comprising: a third transistor having a first terminal, a second terminal, and a control terminal, the first terminal of the third transistor being coupled to the first terminal of the first transistor, the second terminal of the third transistor being coupled to the second terminal of the first transistor, and the control terminal of the third transistor being coupled to the control terminal of the first transistor; and a fifth switch coupled between the first terminal of the first transistor and the first terminal of the third transistor, or coupled between the second terminal of the first transistor and the second terminal of the third transistor, or coupled between the control terminal of the first transistor and the control terminal of the third transistor; or the amplifying circuit further comprising: a fourth transistor having a first terminal, a second terminal, and a control terminal, the first terminal of the fourth transistor being coupled to the first terminal of the second transistor, the second terminal of the fourth transistor being coupled to the second terminal of the second transistor, and the control terminal of the fourth transistor being coupled to the control terminal of the second transistor; and a sixth switch coupled between the first terminal of the second transistor and the first terminal of the fourth transistor, or coupled between the second terminal of the second transistor and the second terminal of the fourth transistor, or coupled between the control terminal of the second transistor and the control terminal of the fourth transistor.
13 . The amplifying circuit according to claim 12 , wherein the control terminal of the first transistor is coupled to a first bias signal end, the first bias signal end is configured to receive a first bias signal, the control terminal of the second transistor is coupled to a second bias signal end, and the second bias signal end is configured to receive a second bias signal.
14 . The amplifying circuit according to claim 13 , further comprising: a first resistor; and a second resistor, wherein the control terminal of the first transistor is coupled to the first bias signal end via the first resistor, and the control terminal of the second transistor is coupled to the second bias signal end via the second resistor.
15 . The amplifying circuit according to claim 3 , further comprising: an intermediate matching network comprising: a second inductor coupled between the second terminal of the first transistor and the control terminal of the second transistor, and coupled in series with the second capacitor; a third capacitor, wherein the first switch and the second capacitor are jointly coupled to a node, and the third capacitor is coupled between the node and a third reference end; and a fourth capacitor coupled between the control terminal of the second transistor and a fourth reference end.
16 . The amplifying circuit according to claim 3 , further comprising: an input matching network coupled to the input terminal of the amplifying circuit; and an output matching network coupled to the output terminal of the amplifying circuit.
17 . The amplifying circuit according to claim 13 , wherein the second terminal of the second transistor is coupled to a first power voltage end and configured to receive a first power voltage signal.
18 . An amplifying circuit comprising: an input terminal configured to receive a first radio frequency signal; an output terminal configured to output an amplified signal; a first transistor having a first terminal, a second terminal, and a control terminal, wherein the control terminal of the first transistor is coupled to the input terminal, and the first terminal of the first transistor is coupled to a first reference end; a second transistor having a first terminal, a second terminal, and a control terminal, wherein the second terminal of the second transistor is coupled to the output terminal; a first inductor coupled between the second terminal of the first transistor and the first terminal of the second transistor; a first switch coupled between the second terminal of the first transistor and the control terminal of the second transistor; a second switch coupled in parallel with the first inductor; a first capacitor; and a third switch coupled in series with the first capacitor, wherein the first capacitor and the third switch are coupled between the first terminal of the second transistor and a second reference end.
19 . The amplifying circuit according to claim 18 , further comprising: a second capacitor coupled in series with the first switch between the second terminal of the first transistor and the control terminal of the second transistor.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims the priority benefits of Taiwanese application no. 111146268, filed on Dec. 2, 2022 and Taiwanese application no. 111146684, filed on Dec. 6, 2022. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification. BACKGROUND Technical Field The disclosure relates to an amplifying circuit. In particular, the disclosure relates to an amplifying circuit that may switch between two different operation modes. Description of Related Art In technical fields, a single-stage or multi-stage amplifying circuit may be used. The single-stage amplifying circuit may meet the requirements for relatively low power consumption, but may provide limited gain. The multi-stage amplifying circuit may provide relatively large gain, but may consume relatively high power. To address the above-mentioned issues, for example, a two-stage amplifier may be used to construct an amplifying circuit. However, in the two-stage amplifier, linearity may be adversely affected during operation. SUMMARY The disclosure provides multiple embodiments of an amplifying circuit, which may switch between at least two different operation modes to achieve better tradeoff among power consumption, gain, and/or linearity. According to an embodiment of the disclosure, an amplifying circuit includes a first transistor, a second transistor, and a switching circuit. The first transistor has a first terminal, a second terminal, and a control terminal. The control terminal of the first transistor is coupled to an input terminal of the amplifying circuit, and the first terminal of the first transistor is coupled to a first reference end. The input terminal of the amplifying circuit is configured to receive a first radio frequency signal. The second transistor has a first terminal, a second terminal, and a control terminal. The first terminal of the second transistor is coupled to the second terminal of the first transistor, and the second terminal of the second transistor is coupled to an output terminal of the amplifying circuit. The output terminal of the amplifying circuit is configured to output an amplified signal. The switching circuit is coupled to the second terminal of the first transistor, the first terminal of the second transistor, and the control terminal of the second transistor. The first transistor amplifies the first radio frequency signal to generate a second radio frequency signal at the second terminal of the first transistor. The switching circuit performs a switching operation to transmit the second radio frequency signal to one of the first terminal of the second transistor and the control terminal of the second transistor. According to another embodiment of the disclosure, an amplifying circuit includes an input terminal, an output terminal, a first transistor, a second transistor, a first inductor, a first switch, a second switch, a first capacitor, and a third switch. The input terminal is configured to receive a first radio frequency signal. The output terminal is configured to output an amplified signal. The first transistor has a first terminal, a second terminal, and a control terminal. The control terminal of the first transistor is coupled to the input terminal of the amplifying circuit, and the first terminal of the first transistor is coupled to a first reference end. The second transistor has a first terminal, a second terminal, and a control terminal. The second terminal of the second transistor is coupled to the output terminal of the amplifying circuit. The first inductor is coupled between the second terminal of the first transistor and the first terminal of the second transistor. The first switch is coupled between the second terminal of the first transistor and the control terminal of the second transistor. The second switch is coupled in parallel with the first inductor. The third switch is coupled in series with the first capacitor. The first capacitor and the third switch are coupled between the first terminal of the second transistor and a second reference end. Based on the foregoing, in the embodiment of the disclosure, the amplifying circuit may be switched between different modes by the switching circuit. As such, depending on requirements, the amplifying circuit may be adaptively switched, for example, may operate in a general mode or a low current mode, accordingly improving the operational efficiency of the amplifying circuit. To make the aforementioned more comprehensible, several embodiments accompanied with drawings are described in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles