Positioning and orientation communication module based on Beidou No.3 navigation system

Abstract

The utility model discloses a positioning directional communication module based on a Beidou No.3 navigation system, which comprises an element board, an upper shielding frame and a lower shielding frame are respectively arranged on the front side and the back side of the element board, and an upper shielding cover and a lower shielding cover are respectively arranged on the upper shielding frame and the lower shielding frame in a matched manner. A radio frequency module, a baseband processing module, a power supply module and an interface unit module are arranged on the element board; the input end of the radio frequency module is connected with an antenna, the output end of the radio frequency module is connected with the baseband processing module, satellite intermediate frequency signals processed by the radio frequency module are output to the baseband processing module, the baseband processing module is connected with the interface processing module, and the interface processing module outputs the signals to the cross-linking equipment after completing level conversion; the radio frequency module, the baseband processing module and the interface unit module are respectively connected with the power supply module, and the power supply module provides a stable power supply. According to the utility model, the problems of single frequency point supported by the existing positioning and orienting module and low positioning and orienting precision are solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of communication systems and relates to a positioning and orientation communication module based on the Beidou-3 navigation system. Background Art

[0002] The BeiDou-3 satellite navigation system is a global satellite navigation system independently built and operated by my country. It has the characteristics of wide coverage, high service performance and strong signal compatibility. It can provide diversified services such as high-precision position, speed and time information, short message communication, international search and rescue, precise single-point positioning, ground-based augmentation, etc. It has been widely used in transportation, public safety, disaster relief and mitigation, agriculture, forestry, animal husbandry and fishery, urban governance and other fields.

[0003] With the full networking of the Beidou-3 satellite navigation system, the navigation receiver industry has developed in an all-round way. Satellite receivers that can only receive satellite signals at a single satellite frequency, the positioning and orientation modules support a single frequency and have poor positioning, which cannot meet the actual application needs; if multiple navigation boards are used to build a multi-antenna system, the front-end, baseband, and clocks of different boards are independent. Even if synchronization methods are used, errors can easily occur between the clocks, which has a great impact on the positioning and orientation measurement accuracy, resulting in low positioning and orientation accuracy, and a lot of hardware redundancy in the communication modules. Utility Model Content

[0004] The purpose of the utility model is to provide a positioning and orientation communication module based on the BeiDou-3 navigation system, which solves the problems of the existing positioning and orientation modules supporting a single frequency point and low positioning and orientation accuracy.

[0005] The technical solution adopted by the utility model is a positioning and directional communication module based on the Beidou-3 navigation system, which includes a component board, an upper shielding frame and a lower shielding frame are respectively arranged on the front and back sides of the component board, an upper shielding cover and a lower shielding cover are respectively arranged on the upper shielding frame and the lower shielding frame, and a radio frequency module, a baseband processing module, a power module and an interface unit module are arranged on the component board; the input end of the radio frequency module is connected to the antenna, and the output end of the radio frequency module is connected to the baseband processing module, and the satellite intermediate frequency signal processed by the radio frequency module is output to the baseband processing module, the baseband processing module is connected to the interface unit module, and the interface unit module outputs the signal to the cross-linking device after completing the level conversion; the radio frequency module, the baseband processing module and the interface unit module are respectively connected to the power module, and the power module provides a stable power supply.

[0006] The utility model is also characterized in that:

[0007] The input end of the RF module includes antenna interface I and antenna interface II. Antenna interface I is connected to RF unit I. RF unit I includes power division circuit I. Power division circuit I adopts PD1700U03W power divider. The input end IN / SUM of PD1700U03W power divider is connected to antenna interface I and feed circuit I. Power division circuit I divides the satellite signal into two outputs. The two outputs are electrically connected to the frequency division circuit and low noise amplifier circuit respectively. The frequency division circuit and low noise amplifier circuit are connected in series and then connected to filter circuit I and RF chip circuit I in turn.

[0008] The frequency division circuit uses the DP2012-1113-1525 frequency divider. The DP2012-1113-1525 frequency divider includes two frequency division circuits. The frequency division circuit divides the signal into two frequency bands: 0~1.3GHz and 1.5~2.5GHz. The COM PORT of one input end is connected to PORT1 of the PD1700U03W power divider, and the COM PORT is connected to PORT2 of the PD1700U03W power divider; filter circuit I uses filters of model PV2G68F, PV5G75J, PV1G91C, and RSFK2492F. The High-band and Low-band output ends of the frequency division circuit are respectively connected to the INPUT of the filter in filter circuit I. Filter circuit I filters the B1, B2, B3, L1, L2, G1, G2, E5, short message S, and L frequencies, and then outputs them to RF chip circuit I. RF chip circuit I uses RF chip model RX3701.

[0009] Antenna interface II is connected to radio frequency unit II. Radio frequency unit II includes power dividing circuit II. Power dividing circuit II adopts PD1500U03W power divider. Input terminal IN of PD1500U03W power divider is connected to antenna interface II and feeding circuit II. Power dividing circuit II divides the input signal into two paths. Power dividing circuit II is electrically connected to filter circuit II and radio frequency chip circuit II in sequence.

[0010] Filter circuit II uses PV5G75J filter and PV2G68F filter. The output terminals OUT1 and OUT2 of the PD1500U03W power divider are respectively connected to the INPUT of the two filters in filter circuit II. Filter circuit II filters the signal. RF chip circuit II uses RX3701 RF chip. The PV5G75J filter filters out the B1, L1, and G1 frequencies, and outputs them through OUTPUT to RFIN_RX2 of the RX3701 RF chip in RF chip circuit II; the PV2G68F filter filters out the B3, L2, and G2 frequencies, and outputs them through OUTPUT to RFIN_RX3 of the RX3701 RF chip in RF chip circuit II.

[0011] The baseband processing module processes, captures, tracks, and resolves the satellite intermediate frequency (IF) signal output by the RF module, outputting the results to the interface unit module. The baseband processing module includes baseband processing circuitry, which utilizes a baseband chip. RF Chip Circuit I and RF Chip Circuit II in the RF module transmit the output signal to the baseband chip, which is electrically connected to the flash circuit, clock circuit, reset circuit, and storage circuit.

[0012] The flash circuit uses a Flash memory model FM25Q129AI3; the clock circuit uses any one of the crystal resonators model 7RC32768F12UC and T53-Y519-10.00MHZ-B, which provides a stable clock signal for the baseband chip; the storage circuit 26 uses a memory model SCB15H1G160AF.

[0013] The interface unit module includes a TTL circuit, which is electrically connected to the baseband chip, the TTL to RS232 circuit, and the TTL to RS422 circuit respectively; the TTL to RS232 circuit converts the TTL level into the RS232 level, and the TTL to RS422 circuit converts the TTL level into the RS422 level. After completing the level conversion, the data is output to the data interface, and the data interface is connected to the cross-linking device; the TTL to RS232 circuit uses an interface chip model TPT3122EH-QF8R, and the TTL to RS422 circuit uses a chip model MAX3490.

[0014] The power module includes a DCDC circuit and a protection circuit. The output voltage of the DCDC circuit is converted into 3.3V, 1.8V, and 0.8V voltages. The DCDC circuit uses power chips with model numbers SGM6603-5.0YN6G / TR, SGM2036-3.3YUDH4G / TR, SGM2036-1.8YUDH4G / TR, and SGM61031XTDE8G / TR. The protection circuit uses an ESD protection circuit with model number LESDLL3.3CT5G.

[0015] The beneficial effects of the utility model are as follows: the positioning and orientation communication module of the utility model is based on the BeiDou-3 navigation system, and has the functions of multi-frequency positioning and orientation, short message communication, and anti-interference, so that the module has the characteristics of high integration, high positioning accuracy, and strong anti-interference ability. It supports BDS, GPS, GLONASS and GALILEO multiple systems and multiple frequency bands, and meets the needs of different users in diversified and complex environments in actual applications. It also has the advantages of high integration, low power consumption and small size. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1This is a structural diagram of the positioning and directional communication module of the utility model based on the BeiDou-3 navigation system;

[0017] Figure 2 This is a system block diagram of the positioning and directional communication module of the utility model based on the BeiDou-3 navigation system.

[0018] In the figure, 1. lower shielding cover, 2. lower shielding frame, 3. component board, 4. antenna interface I, 5. antenna interface II, 6. upper shielding frame, 7. upper shielding cover, 8. data interface, 9. feeding circuit I, 10. power dividing circuit I, 11. frequency dividing circuit, 12. low noise amplifier circuit, 13. filtering circuit I, 14. RF chip circuit I, 15. RF unit I, 16. feeding circuit II, 17. power dividing circuit II, 18. filtering circuit II, 19. RF chip circuit II, 20. RF unit II, 21. RF module, 22. baseband processing circuit, 23. flash circuit, 24. clock circuit, 25. reset circuit, 26. storage circuit, 27. baseband processing module, 28. DCDC circuit, 29. protection circuit, 30. power supply module, 31. TTL circuit, 32. TTL to RS232 circuit, 33. TTL to RS422 circuit, 34. interface unit module. DETAILED DESCRIPTION

[0019] The present invention will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0020] Example 1

[0021] The utility model is based on the positioning and directional communication module of the BeiDou-3 navigation system, and its structure is as follows Figure 1 As shown, it includes a component board 3, an upper shielding frame 6 and a lower shielding frame 2 are respectively provided on the front and back sides of the component board 3, an upper shielding cover 7 and a lower shielding cover 1 are respectively provided on the upper shielding frame 6 and the lower shielding frame 2, and the upper shielding frame 6, the lower shielding frame 2, the upper shielding cover 7 and the lower shielding cover 1 arranged on both sides of the component board 3 are all used for electromagnetic shielding to prevent the component board 3 from being affected by external electromagnetic interference.

[0022] like Figure 2As shown, a radio frequency module 21, a baseband processing module 27, a power supply module 30, and an interface unit module 34 are provided on the component board 3; the input end of the radio frequency module 21 is connected to the antenna for receiving satellite signals and transmitting short message information, and the output end of the radio frequency module 21 is connected to the baseband processing module 27, and the satellite intermediate frequency signal processed by the radio frequency module 21 is output to the baseband processing module 27, and the baseband processing module 27 is connected to the interface unit module 34. The baseband processing module 27 is used for tracking, solving and processing satellite signals, and outputs the processed data to the interface unit module 34, and the interface unit module 34 outputs the data to the cross-linking device after completing the level conversion; the radio frequency module 21, the baseband processing module 27, and the interface unit module 34 are respectively connected to the power supply module 30, and the power supply module 30 provides a stable power supply.

[0023] Example 2

[0024] Based on Example 1, the input end of the RF module 21 includes antenna interface I4 and antenna interface II5. Antenna interface I4 connects to an antenna that supports both full-band and short-band transmissions, while antenna interface II5 connects to a full-band antenna for short-band transmissions, positioning, speed measurement, and direction finding. Both antenna interfaces I4 and II5 use MCX connectors.

[0025] Antenna interface I4 is connected to radio frequency unit I15. Radio frequency unit I15 includes power division circuit I10. Power division circuit I10 adopts PD1700U03W power divider. Input terminal IN / SUM of PD1700U03W power divider is connected to antenna interface I4 and feed circuit I9. Feed circuit I9 provides stable 5V feed for antenna. Power division circuit I10 divides satellite signal into two outputs. The two outputs are electrically connected to frequency division circuit 11 and low noise amplifier circuit 12 respectively. Frequency division circuit 11 and low noise amplifier circuit 12 are connected in series and then connected to filter circuit I13 and radio frequency chip circuit I14 in sequence.

[0026] The frequency division circuit 11 uses a DP2012-1113-1525 frequency divider. The DP2012-1113-1525 frequency divider includes two frequency division circuits. The frequency division circuit 11 divides the signal into two frequency bands: 0-1.3GHz and 1.5-2.5GHz. The COM PORT of one input end is connected to PORT1 of the PD1700U03W power divider, and the COM of the other input end is connected to PORT2 of the PD1700U03W power divider. PORT is connected to PORT2 of the PD1700U03W power divider; the filtering circuit Ⅰ13 uses filters with model numbers PV2G68F, PV5G75J, PV1G91C, and RSFK2492F. The High-band and Low-band output ends of the frequency division circuit 11 are respectively connected to the INPUT of the filter in the filtering circuit Ⅰ13. The filtering circuit Ⅰ13 filters the B1, B2, B3, L1, L2, G1, G2, E5, short message S, and L frequency points, and then outputs them to the RF chip circuit Ⅰ14. The RF chip circuit Ⅰ14 uses a RF chip with model number RX3701 to realize signal amplification, filtering, down-conversion, and up-conversion.

[0027] The antenna interface II5 is connected to the radio frequency unit II20. The radio frequency unit II20 includes a power division circuit II17. The power division circuit II17 adopts a PD1500U03W power divider. The input end IN of the PD1500U03W power divider is connected to the antenna interface II5 and the feeding circuit II16. The feeding circuit II16 provides 5V feeding for the antenna connected to the antenna interface II5. The power division circuit II17 divides the input signal into two paths. The power division circuit II17 is electrically connected to the filter circuit II18 and the radio frequency chip circuit II19 in sequence.

[0028] The filter circuit II18 uses a PV5G75J filter and a PV2G68F filter. The output terminals OUT1 and OUT2 of the PD1500U03W power divider are respectively connected to the INPUTs of the two filters in the filter circuit II18. The filter circuit II18 filters the signal. The RF chip circuit II19 uses an RX3701 RF chip. The PV5G75J filter filters out the B1, L1, and G1 frequency points, and outputs them from the OUTPUT to RFIN_RX2 of the RX3701 RF chip in the RF chip circuit II19; the PV2G68F filter filters out the B3, L2, and G2 frequency points, and outputs them from the OUTPUT to RFIN_RX3 of the RX3701 RF chip in the RF chip circuit II19; the RF chip circuit II19 amplifies, filters, and down-converts the signal, and outputs the satellite intermediate frequency signal to the baseband processing module 27 for processing.

[0029] Example 3

[0030] On the basis of Example 2, the baseband processing module 27 processes, captures, tracks, and resolves the satellite intermediate frequency signal output by the radio frequency module 21 and outputs the result to the interface unit module 34 . The baseband processing module 27 includes a baseband processing circuit 22, which uses a baseband chip. The RF chip circuit I14 and the RF chip circuit II19 in the RF module 21 transmit the output signal to the baseband chip. The baseband chip is electrically connected to a flash circuit 23, a clock circuit 24, a reset circuit 25, and a storage circuit 26. The flash circuit 23 uses a Flash memory model FM25Q128AI3 for storing software programs running on the baseband chip. The clock circuit 24 uses either a 7RC32768F12UC or a T53-Y519-10.00MHZ-B crystal resonator, which provides a stable clock signal for the baseband chip. The storage circuit 26 uses a SCB15H1G160AF memory model to store target codes such as ephemeris and software protocols.

[0031] Interface unit module 34 includes a TTL circuit 31, which is electrically connected to the baseband chip, a TTL-to-RS232 circuit 32, and a TTL-to-RS422 circuit 33. TTL-to-RS232 circuit 32 converts TTL levels to RS232 levels, while TTL-to-RS422 circuit 33 converts TTL levels to RS422 levels. After completing the level conversion, the data is output to data interface 8, which is connected to the crosslinking device. TTL-to-RS232 circuit 32 uses the TPT3122EH-QF8R interface chip, while TTL-to-RS422 circuit 33 uses the MAX3490 chip.

[0032] The power module 30 includes a DCDC circuit 28 and a protection circuit 29. The output voltage of the DCDC circuit 28 is converted into 3.3V, 1.8V, and 0.8V voltages. The DCDC circuit 28 provides a stable power supply for the RF module 21, the baseband processing module 27, and the interface unit module 34. The DCDC circuit 28 uses power chips with model numbers SGM6603-5.0YN6G / TR, SGM2036-3.3YUDH4G / TR, SGM2036-1.8YUDH4G / TR, and SGM61031XTDE8G / TR. The protection circuit 29 uses an ESD protection circuit with model number LESD11LL3.3CT5G to protect the entire circuit.

[0033] Example 4

[0034] The utility model is a positioning and directional communication module based on the BeiDou-3 navigation system. The upper shielding cover 7 and the lower shielding cover 1 have dimensions of 40.00mm*65.00mm. The module has a compact and reasonable design, high integration, and small size, which can meet the requirements of miniaturization design. The module supports multiple systems and frequency bands of BDS, GPS, GLONASS and GALILEO to meet the needs of different users. It supports multiple functions such as pseudo-range differential RTD positioning, carrier phase differential RTK positioning, high-precision timing, dual-antenna directionality and BeiDou short message communication, which can meet the usage requirements of various scenarios. The dual-antenna directionality accuracy is ≤0.1° / m. It supports single-antenna independent positioning and dual-antenna positioning. It has the ability to resist narrowband interference. The power consumption is low, ≤2.5W.

[0035] The working process of the positioning and directional communication module based on the BeiDou-3 navigation system of the present invention is as follows: the power module 30 is powered on, the radio frequency module 21 receives the satellite signal received by the antenna and performs filtering, amplification, and down-conversion processing, and outputs the satellite intermediate frequency signal to the baseband processing module 27;

[0036] The baseband processing module 27 evaluates and screens satellites based on their elevation angle, carrier-to-noise ratio, pseudorange, etc., and then captures, tracks, and calculates the PVT results. The baseband processing module 27 determines whether it has received short messages from other Beidou users by detecting whether the RF module 21 outputs an S-frequency signal. If so, it immediately outputs the short message information through the interface unit module 34.

[0037] The baseband processing module 27 detects whether the Beidou navigation message sent by the reference station is received through the interface unit module 34. If the data is received and the verification is passed, the baseband processing module 27 uses the Beidou navigation message data of the reference station to correct the observation information calculated by the module, thereby performing differential positioning and outputting the precise positioning result. If the Beidou navigation message is not received or the verification fails, the module continues to output the PVT result and the orientation result.

[0038] The baseband processing module 27 detects the short message information input by the user through the interface unit module 34. If there is any, it encodes the message information and outputs the intermediate frequency signal to the radio frequency module 21. The radio frequency module 21 up-converts and amplifies the intermediate frequency signal and outputs the radio frequency signal through the antenna interface I4, which is radiated by the antenna to complete the Beidou short message communication; repeat the above operation or turn off the power to end the process.

Claims

1. The positioning and directional communication module based on the BeiDou-3 navigation system is characterized by: The component board (3) comprises an upper shielding frame (6) and a lower shielding frame (2) respectively arranged on the front and back sides of the component board (3); an upper shielding cover (7) and a lower shielding cover (1) are respectively arranged on the upper shielding frame (6) and the lower shielding frame (2); a radio frequency module (21), a baseband processing module (27), a power module (30), and an interface unit module (34) are arranged on the component board (3); the input end of the radio frequency module (21) is connected to the antenna, the output end of the radio frequency module (21) is connected to the baseband processing module (27), the satellite intermediate frequency signal processed by the radio frequency module (21) is output to the baseband processing module (27), the baseband processing module (27) is connected to the interface unit module (34), and the interface unit module (34) outputs the signal to the cross-linking device after completing the level conversion; the radio frequency module (21), the baseband processing module (27), and the interface unit module (34) are respectively connected to the power module (30), and the power module (30) provides a stable power supply.

2. The positioning and directional communication module based on the BeiDou-3 navigation system according to claim 1, characterized in that: The input end of the radio frequency module (21) includes an antenna interface I (4) and an antenna interface II (5), the antenna interface I (4) is connected to the radio frequency unit I (15), the radio frequency unit I (15) includes a power division circuit I (10), the power division circuit I (10) adopts a PD1700U03W power divider, the input end IN / SUM of the PD1700U03W power divider is connected to the antenna interface I (4) and the feed circuit I (9), the power division circuit I (10) divides the satellite signal into two outputs, the two outputs are respectively electrically connected to the frequency division circuit (11) and the low noise amplifier circuit (12), the frequency division circuit (11) and the low noise amplifier circuit (12) are connected in series and then connected to the filter circuit I (13) and the radio frequency chip circuit I (14).

3. The positioning and directional communication module based on the BeiDou-3 navigation system according to claim 2, characterized in that: The frequency division circuit (11) uses a DP2012-1113-1525 frequency divider. The DP2012-1113-1525 frequency divider includes two frequency division circuits. The frequency division circuit (11) divides the signal into two frequency bands of 0 to 1.3 GHz and 1.5 to 2.5 GHz. The COM PORT of one input end is connected to PORT1 of the PD1700U03W power divider, and the COM of the other input end is connected to PORT2 of the PD1700U03W power divider. PORT is connected to PORT2 of the PD1700U03W power divider; the filter circuit I (13) uses filters of model PV2G68F, PV5G75J, PV1G91C, and RSFK2492F; the output ends High-band and Low-band of the frequency division circuit (11) are respectively connected to the INPUT of the filter in the filter circuit I (13); the filter circuit I (13) filters the B1, B2, B3, L1, L2, G1, G2, E5, short message S, and L frequency points, and then outputs them to the RF chip circuit I (14); the RF chip circuit I (14) uses a RF chip of model RX3701.

4. The positioning and directional communication module based on the BeiDou-3 navigation system according to claim 3, characterized in that: The antenna interface II (5) is connected to the radio frequency unit II (20), and the radio frequency unit II (20) includes a power dividing circuit II (17). The power dividing circuit II (17) adopts a PD1500U03W power divider. The input end IN of the PD1500U03W power divider is connected to the antenna interface II (5) and the feeding circuit II (16). The power dividing circuit II (17) divides the input signal into two paths. The power dividing circuit II (17) is electrically connected to the filter circuit II (18) and the radio frequency chip circuit II (19) in sequence.

5. The positioning and orientation communication module based on the BeiDou-3 navigation system according to claim 4, characterized in that: The filter circuit II (18) adopts a PV5G75J filter and a PV2G68F filter. The output terminals OUT1 and OUT2 of the PD1500U03W power divider are respectively connected to the INPUTs of the two filters in the filter circuit II (18). The filter circuit II (18) filters the signal. The RF chip circuit II (19) adopts an RX3701 RF chip. The PV5G75J filter filters out the B1, L1, and G1 frequency points, and outputs them from the OUTPUT to the RFIN_RX2 of the RX3701 RF chip in the RF chip circuit II (19). The PV2G68F filter filters out the B3, L2, and G2 frequency points, and outputs them from the OUTPUT to the RFIN_RX3 of the RX3701 RF chip in the RF chip circuit II (19).

6. The positioning and directional communication module based on the BeiDou-3 navigation system according to claim 5, characterized in that: The baseband processing module (27) processes, captures, tracks, and solves the satellite intermediate frequency signal output by the radio frequency module (21), and outputs the result to the interface unit module (34); the baseband processing module (27) includes a baseband processing circuit (22), the baseband processing circuit (22) uses a baseband chip, and the radio frequency chip circuit I (14) and the radio frequency chip circuit II (19) in the radio frequency module (21) transmit the output signal to the baseband chip, and the baseband chip is electrically connected to the flash circuit (23), the clock circuit (24), the reset circuit (25), and the storage circuit (26).

7. The positioning and orientation communication module based on the BeiDou-3 navigation system according to claim 6, characterized in that: The flash circuit (23) uses a Flash memory of model FM25Q129AI3; the clock circuit (24) uses any one of the crystal resonators of model 7RC32768F12UC and T53-Y519-10.00MHZ-B, and the crystal resonator provides a stable clock signal for the baseband chip; the storage circuit (26) uses a memory of model SCB15H1G160AF.

8. The positioning and directional communication module based on the BeiDou-3 navigation system according to claim 7, characterized in that: The interface unit module (34) includes a TTL circuit (31), the TTL circuit (31) is electrically connected to the baseband chip, the TTL to RS232 circuit (32), and the TTL to RS422 circuit (33), respectively; the TTL to RS232 circuit (32) converts the TTL level into the RS232 level, and the TTL to RS422 circuit (33) converts the TTL level into the RS422 level. After the level conversion is completed, the data is output to the data interface (8), and the data interface (8) is connected to the cross-linking device; The TTL to RS232 circuit (32) uses an interface chip of model TPT3122EH-QF8R, and the TTL to RS422 circuit (33) uses a chip of model MAX3490.

9. The positioning and directional communication module based on the BeiDou-3 navigation system according to claim 8, characterized in that: The power module (30) includes a DCDC circuit (28) and a protection circuit (29). The output voltage of the DCDC circuit (28) is converted into 3.3V, 1.8V, and 0.8V voltages. The DCDC circuit (28) uses power chips with models SGM6603-5.0YN6G / TR, SGM2036-3.3YUDH4G / TR, SGM2036-1.8YUDH4G / TR, and SGM61031XTDE8G / TR. The protection circuit (29) uses an ESD protection circuit with a model LESD11LL3.3CT5G.

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