Disclosure of Invention
Aiming at the defects brought by the electrostatic discharge channel in the prior art, the invention provides the single-pole double-throw radio frequency switch, a novel radio frequency switch circuit structure is adopted, and a bidirectional diode is bridged at two ends of a capacitor of the electrostatic discharge channel, so that a chip is ensured to introduce a small parasitic effect while carrying out electrostatic protection, and the impedance matching performance and the linearity of the channel are improved.
The specific implementation content of the invention is as follows:
the invention provides a single-pole double-throw radio frequency switch which is provided with an ANT antenna input port, wherein a TX-ANT channel, an ANT-RX channel and an electrostatic discharge channel are connected with the ANT antenna input port; the TX-ANT channel and the ANT-RX channel both comprise a series branch knot and a parallel branch knot;
the input port of the ANT antenna is respectively connected with the series branches of the TX-ANT channel and the ANT-RX channel, and then connected with the corresponding parallel branches through the respective connected series branches to lead out the corresponding TX port and RX port;
the series branch of the TX-ANT channel comprises n series transistors, and the parallel branch of the TX-ANT channel comprises m series transistors; the series branch of the ANT-RX channel comprises m series transistors, and the parallel branch of the ANT-RX channel comprises n series transistors; the gates of the transistors in the series branch of the TX-ANT channel and the parallel branch of the ANT-RX channel are connected with a logic control level VC; the grid electrodes of the transistors of the parallel branch of the TX-ANT channel and the series branch of the ANT-RX channel are connected with a logic control level NVC; the amplitude of the logic control level VC is equal to that of the logic control level NVC, and the phase difference is 180 degrees;
the static leakage channels are provided with three groups, the output end of each group of static leakage channels is grounded, the input ends of one group of static leakage channels are lapped on an ANT antenna input port, the input ends of one group of static leakage channels are lapped on a TX port, and the input ends of one group of static leakage channels are lapped on an RX port;
the electrostatic discharge channel comprises a transistor M1-a transistor Mk, wherein k groups of transistors are connected in series through the source and the drain of each transistor; the value of k is equal to the larger of the value m and the value n;
a capacitor C is respectively connected to the source electrode of the transistor M1 and the drain electrode of the transistor Mk in a bridging mode; two diode groups connected in parallel are lapped at two ends of each capacitor C; one diode group comprises a plurality of diodes with the same direction, and the inter-group directions of two groups of diode groups corresponding to one capacitor C are opposite;
the gates of the transistors M1 and Mk are connected with a logic control low level VC 1;
the input end of the capacitor C connected to the source of the transistor M1 is the input end of the electrostatic discharge channel, and the output end of the capacitor C connected to the drain of the transistor Mk is the output end of the electrostatic discharge channel.
In order to better implement the present invention, the serial branch of the TX-ANT channel is provided with n transistors, i.e., a transistor M11-a transistor M1n, the n transistors are connected in series through the source and the drain of each other, the source of the transistor M11 is connected to the ANT antenna input port, and the drain of the transistor M1n is connected to the parallel branch of the TX-ANT channel
N +1 transistor constant voltage resistors R1, n transistor stabilizing resistors R2 and n level stabilizing resistors Rb are arranged in the series branch of the TX-ANT channel;
n-1 transistor constant voltage resistors R1 are respectively lapped between the source and the drain of the transistor M11-the transistor M1n, and two transistor constant voltage resistors R1 are respectively lapped on the source of the transistor M11 and the drain of the transistor M1 n; then n +1 transistors of the serial branch of the TX-ANT channel are connected with equal voltage resistors R1 in an overlapping mode;
the n transistor stabilizing resistors R2 are respectively and correspondingly lapped on the grid electrodes of the transistor M11-the transistor M1n and then are connected with a logic control level VC;
the n level stabilizing resistors Rb are grounded and correspondingly connected to the body ends of the transistor M11 and the transistor M1n respectively.
In order to better realize the invention, the parallel branch of the TX-ANT channel is provided with m transistors, namely a transistor N11 and a transistor N1m, wherein the m transistors are connected in series through the source and the drain of each other and then connected in parallel and lapped on the TX-ANT channel through the drain of a transistor N11;
m transistor constant-voltage resistors R1, m transistor stable resistors R2 and m level stable resistors Rb are arranged in parallel branches of the TX-ANT channel;
the m transistor constant voltage resistors R1 are correspondingly lapped on the source and the drain of one transistor of the transistors N11-N1 m respectively;
the m transistor stabilizing resistors R2 are correspondingly lapped on the grid electrode of one transistor from the transistor N11 to the transistor N1m respectively and then are connected with a logic control level NVC;
m of the level stabilizing resistors Rb are grounded and then respectively and correspondingly connected to the body terminal of one of the transistors N11-N1 m.
In order to better implement the present invention, a fixed resistor R3 is further disposed in the parallel branch of the TX-ANT channel, the fixed resistor R3 is grounded and then connected to the source of the transistor N1m, and the resistance of the fixed resistor R3 is 50 ohms.
In order to better implement the present invention, the serial branch of the ANT-RX channel is provided with M transistors M21-M2M, the M transistors are connected in series through their sources and drains, the source of the transistor M21 is connected to the ANT antenna input port, the drain of the transistor M2M is connected to the parallel branch of the ANT-RX channel
M +1 transistor constant voltage resistors R1, m transistor stabilizing resistors R2 and m level stabilizing resistors Rb are arranged in the series branch of the ANT-RX channel;
m-1 transistor constant voltage resistors R1 are respectively lapped between the source and the drain of the transistor M21-the transistor M2M, and two transistor constant voltage resistors R1 are respectively lapped on the source of the transistor M21 and the drain of the transistor M2M; then m +1 transistors of the serial branch of the ANT-RX channel are connected with equal voltage resistors R1 in an overlapping mode;
the M transistor stabilizing resistors R2 are respectively and correspondingly lapped on the grid electrodes of the transistor M21-the transistor M2M and then are connected with a logic control level VC;
m level stabilizing resistors Rb are grounded and correspondingly connected to the body terminals of the transistor M21-the transistor M2M respectively.
In order to better implement the invention, the parallel branch of the ANT-RX channel is provided with N transistors, namely a transistor N21 and a transistor N2N, wherein the N transistors are connected in series through the source and the drain of each other and then connected in parallel on the ANT-RX channel through the drain of a transistor N21;
n transistor constant voltage resistors R1, n transistor stable resistors R2 and n level stable resistors Rb are arranged in parallel branches of the ANT-RX channel;
the N transistor constant voltage resistors R1 are correspondingly lapped on the source and the drain of one transistor of the transistors N21-N2N respectively;
the N transistor stabilizing resistors R2 are correspondingly lapped on the grid electrode of one transistor from the transistor N21 to the transistor N2N respectively and then are connected with a logic control level NVC;
the N level stabilizing resistors Rb are grounded and respectively connected to the body terminal of one of the transistors N21-N2N.
In order to better implement the present invention, a fixed resistor R3 is further disposed in the parallel branch of the ANT-RX channel, the fixed resistor R3 is grounded and then connected to the source of the transistor N2N, and the resistance of the fixed resistor R3 is 50 ohms.
In order to better implement the invention, further, each electrostatic discharge channel is further provided with k +1 transistor equal-voltage resistors R1, k transistor stabilizing resistors R2 and k level stabilizing resistors Rb;
k-1 transistor constant voltage resistors R1 are respectively lapped between the source and the drain of the transistor M1-transistor Mk, and two transistor constant voltage resistors R1 are respectively lapped on the source of the transistor M1 and the drain of the transistor Mk;
k transistor stabilization resistors R2 are respectively and correspondingly lapped on the grid electrodes of the transistors M1-Mk and then are connected with a logic control low level VC 1;
k level stabilizing resistors Rb are grounded and correspondingly connected to the body ends of the transistors M1 and Mk respectively.
In order to better implement the present invention, the ANT-RX channel is further provided with two capacitors C1, and two capacitors C1 are respectively disposed at a side of the ANT-RX channel connected to the ANT antenna input port and at a side of the RX port.
In order to better implement the present invention, the TX-ANT channel is further provided with two capacitors C1, and two capacitors C1 are respectively disposed on a side of the TX-ANT channel connected to the ANT antenna input port and a side of the TX port.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) the electrostatic discharge channel is connected with the bidirectional diode at two ends of the capacitor in a bridging manner, so that a small parasitic effect is introduced while the chip is subjected to electrostatic protection, and the impedance matching performance and linearity of the channel are improved;
(2) the influence of the electrostatic discharge channel on the impedance matching and the linearity of the channel is solved, and the stability of the chip is improved;
(3) the structure of the invention ensures that the voltage differences born by the transistor source and drain electrodes stacked by the serial branch and the parallel branch are equal and are both lower than the breakdown voltage of the transistor process, thereby improving the stability of the circuit.
Detailed Description
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and therefore should not be considered as a limitation to the scope of protection. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Example 1:
the embodiment provides a single-pole double-throw radio frequency switch, as shown in fig. 1 and fig. 2, which is provided with an ANT antenna input port, and a TX-ANT channel, an ANT-RX channel and an electrostatic discharge channel are connected to the ANT antenna input port; the TX-ANT channel and the ANT-RX channel both comprise a series branch knot and a parallel branch knot;
the input port of the ANT antenna is respectively connected with the series branches of the TX-ANT channel and the ANT-RX channel, and then connected with the corresponding parallel branches through the respective connected series branches to lead out the corresponding TX port and RX port;
the series branch of the TX-ANT channel comprises n series transistors, and the parallel branch of the TX-ANT channel comprises m series transistors; the series branch of the ANT-RX channel comprises m series transistors, and the parallel branch of the ANT-RX channel comprises n series transistors; the gates of the transistors in the series branch of the TX-ANT channel and the parallel branch of the ANT-RX channel are connected with a logic control level VC; the grid electrodes of the transistors of the parallel branch of the TX-ANT channel and the series branch of the ANT-RX channel are connected with a logic control level NVC; the amplitude of the logic control level VC is equal to that of the logic control level NVC, and the phase difference is 180 degrees;
the static leakage channels are provided with three groups, the output end of each group of static leakage channels is grounded, the input ends of one group of static leakage channels are lapped on an ANT antenna input port, the input ends of one group of static leakage channels are lapped on a TX port, and the input ends of one group of static leakage channels are lapped on an RX port;
the electrostatic discharge channel comprises a transistor M1-a transistor Mk, wherein k groups of transistors are connected in series through the source and the drain of each transistor; the value of k is equal to the larger of the value m and the value n;
a capacitor C is respectively connected to the source electrode of the transistor M1 and the drain electrode of the transistor Mk in a bridging mode; two diode groups connected in parallel are lapped at two ends of each capacitor C; one diode group comprises a plurality of diodes with the same direction, and the inter-group directions of two groups of diode groups corresponding to one capacitor C are opposite;
the gates of the transistors M1 and Mk are connected with a logic control low level VC 1;
the input end of the capacitor C connected to the source of the transistor M1 is the input end of the electrostatic discharge channel, and the output end of the capacitor C connected to the drain of the transistor Mk is the output end of the electrostatic discharge channel.
The working principle is as follows: fig. 2 shows a schematic diagram of an electrostatic discharge channel at a port, wherein a capacitor C is connected to an input port and an output port of the channel, respectively, and the other end of the capacitor is connected to a core circuit of the electrostatic discharge channel formed by stacking n transistors. Two bidirectional diodes are bridged at two ends of the capacitor C to be used as discharge channels, and two diodes are cascaded in each direction. The core circuit of the electrostatic discharge channel is formed by stacking n MOS transistors, wherein two resistors R1 are connected between the drain and the source of the transistor M1, so as to ensure that the dc levels between the drain and the source of the transistor are equal during normal operation. The source of M2 is connected to the drain of M1, and two resistors R1 are connected between the drain and source of transistor M2, similar to transistor M1. By analogy, the drain electrode of the transistor Mn-1 is connected with the source electrode of the Mn, and two resistors R1 are bridged between the drain electrode and the source electrode of the Mn, so that the voltage difference between the drain electrode and the source electrode of all the transistors in the series branch section is equal, and the problem that the transistors are burnt out due to overlarge voltage difference between the drain electrode and the source electrode of one transistor to cause chip failure during static electricity discharge is avoided. The gates of the transistors M1-Mn are connected with a resistor R2 with a large resistance value, the other end of the resistor R2 is connected with a logic control low level VC1 of the series branch circuit, so that the transistors are in a conducting state, and when the static electricity of the input port is large, the charges are discharged to the ground through the diode.
Example 2:
in this embodiment, on the basis of the above embodiment 1, in order to better implement the present invention, as shown in fig. 1 and fig. 2, the serial branch of the TX-ANT channel is provided with n transistors, i.e., a transistor M11 and a transistor M1n, the n transistors are connected in series through their sources and drains, the source of the transistor M11 is connected to the ANT antenna input port, and the drain of the transistor M1n is connected to the parallel branch of the TX-ANT channel
N +1 transistor constant voltage resistors R1, n transistor stabilizing resistors R2 and n level stabilizing resistors Rb are arranged in the series branch of the TX-ANT channel;
n-1 transistor constant voltage resistors R1 are respectively lapped between the source and the drain of the transistor M11-the transistor M1n, and two transistor constant voltage resistors R1 are respectively lapped on the source of the transistor M11 and the drain of the transistor M1 n; then n +1 transistors of the serial branch of the TX-ANT channel are connected with equal voltage resistors R1 in an overlapping mode;
the n transistor stabilizing resistors R2 are respectively and correspondingly lapped on the grid electrodes of the transistor M11-the transistor M1n and then are connected with a logic control level VC;
the n level stabilizing resistors Rb are grounded and correspondingly connected to the body ends of the transistor M11 and the transistor M1n respectively.
Furthermore, a parallel branch of the TX-ANT channel is provided with a transistor N11-a transistor N1m which are m transistors in total, and the m transistors are connected in series through the source and the drain of each other and then connected in parallel and lapped on the TX-ANT channel through the drain of the transistor N11;
m transistor constant-voltage resistors R1, m transistor stable resistors R2 and m level stable resistors Rb are arranged in parallel branches of the TX-ANT channel;
the m transistor constant voltage resistors R1 are correspondingly lapped on the source and the drain of one transistor of the transistors N11-N1 m respectively;
the m transistor stabilizing resistors R2 are correspondingly lapped on the grid electrode of one transistor from the transistor N11 to the transistor N1m respectively and then are connected with a logic control level NVC;
m of the level stabilizing resistors Rb are grounded and then respectively and correspondingly connected to the body terminal of one of the transistors N11-N1 m.
Furthermore, a fixed resistor R3 is further arranged in the parallel branch of the TX-ANT channel, the fixed resistor R3 is connected with the source of the transistor N1m after being grounded, and the resistance value of the fixed resistor R3 is 50 ohms.
Further, the series branch of the ANT-RX channel is provided with M transistors of M21-M2M, the M transistors are connected in series through the source and the drain of each other, the source of the transistor M21 is connected with the ANT antenna input port, and the drain of the transistor M2M is connected with the parallel branch of the ANT-RX channel
M +1 transistor constant voltage resistors R1, m transistor stabilizing resistors R2 and m level stabilizing resistors Rb are arranged in the series branch of the ANT-RX channel;
m-1 transistor constant voltage resistors R1 are respectively lapped between the source and the drain of the transistor M21-the transistor M2M, and two transistor constant voltage resistors R1 are respectively lapped on the source of the transistor M21 and the drain of the transistor M2M; then m +1 transistors of the serial branch of the ANT-RX channel are connected with equal voltage resistors R1 in an overlapping mode;
the M transistor stabilizing resistors R2 are respectively and correspondingly lapped on the grid electrodes of the transistor M21-the transistor M2M and then are connected with a logic control level VC;
m level stabilizing resistors Rb are grounded and correspondingly connected to the body terminals of the transistor M21-the transistor M2M respectively.
Furthermore, the parallel branch of the ANT-RX channel is provided with N transistors, namely a transistor N21 and a transistor N2N, the N transistors are connected in series through the source and the drain of each other and then connected in parallel and lapped on the ANT-RX channel through the drain of the transistor N21;
n transistor constant voltage resistors R1, n transistor stable resistors R2 and n level stable resistors Rb are arranged in parallel branches of the ANT-RX channel;
the N transistor constant voltage resistors R1 are correspondingly lapped on the source and the drain of one transistor of the transistors N21-N2N respectively;
the N transistor stabilizing resistors R2 are correspondingly lapped on the grid electrode of one transistor from the transistor N21 to the transistor N2N respectively and then are connected with a logic control level NVC;
the N level stabilizing resistors Rb are grounded and respectively connected to the body terminal of one of the transistors N21-N2N.
Furthermore, a fixed resistor R3 is further arranged in the parallel branch of the ANT-RX channel, the fixed resistor R3 is connected with the source of the transistor N2N after being grounded, and the resistance value of the fixed resistor R3 is 50 ohms.
Furthermore, each electrostatic discharge channel is also provided with k +1 transistor constant voltage resistors R1, k transistor stabilizing resistors R2 and k level stabilizing resistors Rb;
k-1 transistor constant voltage resistors R1 are respectively lapped between the source and the drain of the transistor M1-transistor Mk, and two transistor constant voltage resistors R1 are respectively lapped on the source of the transistor M1 and the drain of the transistor Mk;
k transistor stabilization resistors R2 are respectively and correspondingly lapped on the grid electrodes of the transistors M1-Mk and then are connected with a logic control low level VC 1;
k level stabilizing resistors Rb are grounded and correspondingly connected to the body ends of the transistors M1 and Mk respectively.
Further, the ANT-RX channel is further provided with two capacitors C1, and two capacitors C1 are respectively disposed on a side of the ANT-RX channel connected to an ANT antenna input port and a side of an RX port.
Further, the TX-ANT channel is further provided with two capacitors C1, and the two capacitors C1 are respectively disposed on one side of the TX-ANT channel connected to the ANT antenna input port and one side of the TX port.
The working principle is as follows: a transistor constant voltage resistor R1 is lapped between the drain and the source of the transistor to ensure that the direct current level between the drain and the source of the transistor is equal during normal operation;
the transistor stabilizing resistor R2 adopts a resistor with a larger resistance value, the resistance value is about dozens of K omega, 60K omega can be selected, and the access of a large resistance value R2 avoids the breakdown of the gate oxide layer capacitor of the transistor due to higher fluctuation generated by controlling a logic level, and improves the stability of the series branch, the parallel branch and the electrostatic discharge channel.
The level stabilizing resistor Rb is grounded and then connected with the body end of the transistor in an overlapping mode, and the direct-current level of the body end is guaranteed to maintain a certain potential.
The setting of the resistor R3 is fixed to ensure that when the channel is closed, the impedance matching between the port and the external rf circuit is achieved.
Other parts of this embodiment are the same as those of embodiment 1, and thus are not described again.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications and equivalent variations of the above embodiments according to the technical spirit of the present invention are included in the scope of the present invention.