CN219834139U - Radio frequency front-end circuit without switch structure - Google Patents
Radio frequency front-end circuit without switch structure Download PDFInfo
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- CN219834139U CN219834139U CN202320970752.5U CN202320970752U CN219834139U CN 219834139 U CN219834139 U CN 219834139U CN 202320970752 U CN202320970752 U CN 202320970752U CN 219834139 U CN219834139 U CN 219834139U
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Abstract
The utility model discloses a radio frequency front-end circuit without a switch structure, which comprises: a transistor, a Cascode transistor, a first switch, a second switch, a resonant inductor, an antenna, and a transformer; one path of the base electrode of the transistor is connected with a first bias voltage through a first switch, and the other path of the base electrode of the transistor is connected with a second bias voltage through a second switch; the collector of the transistor is connected with the emitter of the Cascode tube, and the emitter of the transistor is connected with a resonant inductor, an antenna and a primary coil of a transformer; one end of the resonant inductor is connected with the emitter of the transistor, and the other end of the resonant inductor is grounded; one end of a primary coil of the transformer is connected with an emitter of the transistor, and the other end of the primary coil of the transformer is grounded; the secondary coil of the transformer is connected with the output end of the power amplifier.
Description
Technical Field
The utility model belongs to the technical field of electronic circuit design and wireless communication, and relates to a radio frequency front-end circuit without a switch structure.
Background
Over the past several decades, wireless communication technologies have evolved greatly, and a vast array of wireless communication systems and protocols, GSM, CDMA, WCDMA, TDS-CDMA, CDMA2000, LTE, wiFi, bluetooth, 5G communications, have evolved, driving economic and social advances. As an important component of a wireless communication transceiver system, the performance of the radio frequency front-end increasingly affects the performance of the overall radio frequency transceiver.
The radio frequency front end mainly comprises a Power Amplifier (PA), a Low Noise Amplifier (LNA), a radio frequency switch and the like. In the fields of 5G high frequency and the like, the integration level of the radio frequency front end is high, the power amplifier and the low noise amplifier share the same radio frequency bonding pad, and a radio frequency switch is needed to switch the receiving state and the transmitting state. With the increasing evolution of technology, the performance index requirement of the radio frequency front end is also higher. The lower the insertion loss of the radio frequency switch is, the larger the power which can be pushed out by the transmitting link is, and the higher the linearity and the efficiency are; meanwhile, the noise figure of the receiving link is smaller.
Conventional field effect transistors (MOSFETs) or bipolar transistors (BJTs) have large insertion losses when switched, especially in the high frequency domain or become unacceptable. The Power Amplifier (PA) is arranged behind the Power Amplifier (PA), so that the output power and efficiency of the Power Amplifier (PA) are often influenced, and the output power and efficiency of a transmitter are further influenced; the noise figure of the receiving link is greatly deteriorated when the noise amplifier is placed at the front end of a Low Noise Amplifier (LNA), and key indexes such as signal-to-noise ratio and receiving sensitivity of the receiver are further affected. The conventional switch on the chip has extremely large insertion loss at high frequency, so that impedance conversion is generally performed in a lambda/4 transmission line+switch mode in the high frequency field to optimize the insertion loss of the radio frequency switch. As shown in fig. 1, in order to achieve both the transmit link output power and the receive link noise figure, a switch is often placed at the receiver front end. When the receiver works, the Power Amplifier (PA) is turned off, and because the PA adopts a cascode structure, the collector impedance of a cascode transistor is larger when the receiver is turned off, and the high resistance is easier to realize when the receiver is turned off. When the transmitter is in operation, the Low Noise Amplifier (LNA) is turned off, which requires a high impedance when turned off, but the Low Noise Amplifier (LNA) often adopts a common emitter architecture, so that the high impedance when turned off is difficult to achieve in order to achieve a 50 ohm match with the antenna in the operating state. A lambda/4 transmission line + switch module 100 is added to achieve high resistance. In the receiver operating state, sw_ctrl is low, transistor M1 is off, and the antenna sees low resistance due to the impedance transformation of the lambda/4 transmission line, and the signal is amplified by the base of the transmission line input to M2. In the operating state of the transmitter, sw_ctrl is high, the transistor M1 is turned on, and the antenna detects high resistance due to the impedance transformation of the λ/4 transmission line, and a signal cannot be input to the base of M2 through the transmission line.
Because the module 100 of fig. 1, in which the λ/4 transmission line+switch is added to the front end of the Low Noise Amplifier (LNA), the insertion loss is very large in the high frequency band, which greatly worsens the noise figure of the receiver, and the area of the λ/4 transmission line is large, which greatly affects the area and layout of the radio frequency front end. Therefore, the insertion loss of the radio frequency switch is still kept at 1.5dB or more by adopting the lambda/4 transmission line plus switch module. And the lambda/4 transmission line or its equivalent CLC network occupies a very large area on the chip.
Disclosure of Invention
The utility model aims to: the utility model discloses a radio frequency front-end circuit without a switch structure, which aims to solve the problems that a radio frequency switch deteriorates the noise coefficient of a receiving link and influences the output power of a transmitting link.
The technical scheme is as follows: a radio frequency front-end circuit of a switchless architecture, comprising: a transistor, a Cascode transistor, a first switch, a second switch, a resonant inductor, an antenna, and a transformer;
one path of the base electrode of the transistor is connected with a first bias voltage through a first switch, and the other path of the base electrode of the transistor is connected with a second bias voltage through a second switch; the collector of the transistor is connected with the emitter of the Cascode tube, and the emitter of the transistor is connected with a resonant inductor, an antenna and a primary coil of a transformer;
one end of the resonant inductor is connected with the emitter of the transistor, and the other end of the resonant inductor is grounded;
one end of a primary coil of the transformer is connected with an emitter of the transistor, and the other end of the primary coil of the transformer is grounded;
the secondary coil of the transformer is connected with a power amplifier.
Further, when the radio frequency front end circuit without the switch structure is operated in a transmitting mode, the first switch is turned on, the second switch is turned on, and the first bias voltage is set to a voltage that causes the transistor to assume an off state.
Further, the first bias voltage is a voltage set to cause the transistor to assume an off state, including the first bias voltage being set to 0V.
Further, when the radio frequency front end circuit without the switch structure is operated in the receiving mode, the first switch is closed, the second switch is turned on, and the second bias voltage is set to a voltage that causes the transistor to operate in the linear region.
Further, the second bias voltage is set to a voltage that causes the transistor to operate in a linear region, including the second bias voltage being set to 0.7V.
Further, the power amplifier is a common-base amplifier.
Further, when the radio frequency front-end circuit without the switch structure works in a transmitting mode, the resonance inductor resonates with a parasitic capacitance in a transistor off state.
Further, when the radio frequency front-end circuit without the switch structure works in a receiving mode, the resonance inductance, the parasitic capacitance of the transistor working in a linear region state and the transconductance of the transistor working in a linear region state are in conjugate match with the impedance of the antenna.
Further, the transistor is a field effect transistor.
Further, the transistor is a bipolar transistor.
The beneficial effects are that: compared with the prior art, the radio frequency front end of the utility model does not deteriorate the output power and efficiency of a transmitting link and the noise coefficient of a receiving link; meanwhile, the radio frequency front end of the utility model does not adopt lambda/4 transmission line or CLC network to realize impedance transformation, thereby saving the chip area and facilitating the layout of the chip.
Drawings
FIG. 1 is a conventional RF front-end circuit diagram;
FIG. 2 is a circuit diagram of a RF front end without a switch structure according to the present utility model;
fig. 3 is a circuit diagram of a radio frequency front end with a switch-free structure according to embodiment 2.
Detailed Description
The technical scheme of the utility model is further described with reference to the accompanying drawings and the embodiments.
Example 1:
as shown in fig. 2, this embodiment discloses a radio frequency front-end circuit with a switch-free structure, in which the receiving front-end is based on a common-base amplifier structure, and mainly includes: a transistor M1, a Cascode transistor M2, a first switch S1, a second switch S2, a resonant inductance L1, an antenna ANT, and a transformer B1. One path of the base electrode of the transistor M1 is connected with the first bias voltage VB1 through the first switch S1, and the other path of the base electrode of the transistor M1 is connected with the second bias voltage V through the second switch S2 B2 . The collector of the transistor M1 is connected with the emitter of the Cascode transistor M2, the emitter of the transistor M1 is connected with a resonant inductor L1, an antenna ANT and a primary coil of a transformer B1, one end of the resonant inductor L1 is connected with the emitter of the transistor M1, and the other end of the resonant inductor L1 is grounded. One end of the primary coil of the transformer B1 is connected to the emitter of the transistor M1, and the other end of the primary coil of the transformer B1 is grounded. The secondary winding of the transformer B1 is connected to the output of the PA. The transistors M1 and M2 in this embodiment may be MOS transistors.
When the RF front-end circuit worksIn the emission mode, the first switch S1 is turned on, the second switch S2 is turned off, and the base of the transistor M1 is biased at V B1 This voltage is set around 0V, so that the transistor M1 assumes an off state, where the impedance seen by the antenna end is:
wherein: r is R off Is the impedance of the transistor M1 in the off state, C off Is the parasitic capacitance of the transistor M1 in the off state.
When the RF front-end circuit is operated in the receiving mode, the first switch S1 is closed, the second switch S2 is turned on, and the base of the transistor M1 is biased at V B2 This voltage is set at about 0.7V, and the transistor M1 operates in the linear region, and the impedance seen at the antenna end is:
wherein R is on For the impedance of transistor M1 operating in the linear region, C on Parasitic capacitance g for transistor M1 operating in the linear region m Is the transconductance of transistor M1 operating in the linear regime.
Usually R off Often a very large impedance, R on Can be larger than several kiloohms, and selects proper transistor parameters and transistor bias voltage V B1 And V B2 Resonant inductance L 1 . In the off state, L 1 And C off Resonance, the impedance seen by the antenna end is R which presents high impedance off The signal cannot be delivered to the receiver. In the on state, L 1 、C on And g m The formed network is conjugate matched with the impedance of the antenna, and the signal is input to the emitter of the transistor M1 in the receiver and amplified by the common-base amplifier and the Cascode tube M2.
Therefore, the circuit structure of the embodiment can realize high impedance when being turned off and can realize conjugate matching when being turned on. The switch and lambda/4 transmission line (or its equivalent CLC network) are omitted.
Example 2:
based on embodiment 1, the transistor M1 in the radio frequency front-end circuit of the switchless structure disclosed in embodiment 1 may be replaced by a field effect transistor (MOSFET), see in particular fig. 3.
Claims (10)
1. A radio frequency front-end circuit of a switchless architecture, characterized in that: comprising the following steps: a transistor, a Cascode transistor, a first switch, a second switch, a resonant inductor, an antenna, and a transformer;
one path of the base electrode of the transistor is connected with a first bias voltage through a first switch, and the other path of the base electrode of the transistor is connected with a second bias voltage through a second switch; the collector of the transistor is connected with the emitter of the Cascode tube, and the emitter of the transistor is connected with a resonant inductor, an antenna and a primary coil of a transformer;
one end of the resonant inductor is connected with the emitter of the transistor, and the other end of the resonant inductor is grounded;
one end of a primary coil of the transformer is connected with an emitter of the transistor, and the other end of the primary coil of the transformer is grounded;
the secondary coil of the transformer is connected with a power amplifier.
2. The switch-less rf front-end circuit of claim 1, wherein: when the radio frequency front-end circuit without the switch structure works in a transmitting mode, the first switch is turned on, the second switch is turned on, and the first bias voltage is set to a voltage for enabling the transistor to be in an off state.
3. The switch-less rf front-end circuit of claim 2, wherein: the first bias voltage is a voltage set to cause the transistor to assume an off state, including the first bias voltage being set to 0V.
4. The switch-less rf front-end circuit of claim 1, wherein: when the radio frequency front-end circuit of the switchless structure is operated in the receiving mode, the first switch is closed and the second switch is turned on, and the second bias voltage is set to a voltage that causes the transistor to operate in the linear region.
5. The switch-less rf front-end circuit of claim 1, wherein: the second bias voltage is set to a voltage that causes the transistor to operate in a linear region, including the second bias voltage being set to 0.7V.
6. The switch-less rf front-end circuit of claim 1, wherein: the power amplifier is a common-base amplifier.
7. The switch-less rf front-end circuit of claim 2, wherein: when the radio frequency front-end circuit without the switch structure works in a transmitting mode, the resonance inductor resonates with a parasitic capacitor in the off state of the transistor.
8. The switch-less rf front-end circuit of claim 4, wherein: when the radio frequency front-end circuit without the switch structure works in a receiving mode, the resonance inductance, the parasitic capacitance of the transistor working in a linear region state and the transconductance of the transistor working in a linear region state are in conjugate match with the impedance of the antenna.
9. The switch-less rf front-end circuit of claim 1, wherein: the transistor is a field effect transistor.
10. The switch-less rf front-end circuit of claim 1, wherein: the transistor is a bipolar transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320970752.5U CN219834139U (en) | 2023-04-25 | 2023-04-25 | Radio frequency front-end circuit without switch structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320970752.5U CN219834139U (en) | 2023-04-25 | 2023-04-25 | Radio frequency front-end circuit without switch structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN219834139U true CN219834139U (en) | 2023-10-13 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202320970752.5U Active CN219834139U (en) | 2023-04-25 | 2023-04-25 | Radio frequency front-end circuit without switch structure |
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| Country | Link |
|---|---|
| CN (1) | CN219834139U (en) |
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2023
- 2023-04-25 CN CN202320970752.5U patent/CN219834139U/en active Active
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