Description:FORM – 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
(SEE SECTION 10, RULE 13)

A SYSTEM AND A METHOD FOR POWER CONVERTER SWITCHING FREQUENCY SUPPRESSION

BHARAT ELECTRONICS LIMITED

WITH ADDRESS:
OUTER RING ROAD, NAGAVARA, BANGALORE 560045, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
TECHNICAL FIELD
[0001] The present invention relates generally to DCDC converter switching frequency, more particularly to a system and a method for suppression of power converter switching frequency.
BACKGROUND

[0002] Frequency synthesis by PLL approach finds many application in RADAR and Communication Systems. Lock time, spurious and phase noise are the three important parameters of PLL. As the technology is advancing PLL with less spurious, less lock time and low phase noise are required. Spurious is an undesired signal generated in the device which can be from reference oscillator, PFD, microcontroller clocks or from power supplies, digital circuitry or any nearby component. These spurs when get amplified in the RF circuitry and mix with other components produce in band signals, which may lead to wrong interpretation of data or may degrade system SNR. Identification and suppression of spurious is a critical task.
[0003] A paper titled “PCB layout optimization using external LDO for low EMI”. LDOs are useful since LDOs do not generate switching noise, while synchronous DC-DC buck converters do. Because of this advantage, it is easy for designers to ignore the importance of the system-level PCB layout design. To control EMI at the output terminal of an LDO, the proper PCB layout is essential. This paper evaluates two types of power trace layouts for LDO test benches with a 10-layer stack-up PCB. Time-domain measurement of voltage at the output terminal of an LDO and an acoustic measurement were performed for the evaluation. The voltage drop decreased by 65mV after the layout of the linear regulator output was revised.
[0004] A paper titled “PCB layout modification to change the noise transfer path”. To meet EN55015 regulation, the magnetic field distribution of 20W LED driver was tested by near field probes and spectrum analyzer. According to the tested magnetic strength, the interference sources and transfer paths on the PCB board were identified. Because the interference source cannot be changed, the PCB modification scheme was proposed to change the transfer path for the interference suppression. With the updated PCB layout, the conductive emission test result was dramatically improved to meet EN55015 regulation limit.
[0005] A paper titled “Compact and high density integrated design with high isolation for S-band up-conversion system”. A compact and high density integrated design with high isolation for S-band up-conversion system is presented in this paper. The system has two phase locked 100p(PLL) frequency sources which provide local oscillator(LO) signals for frequency conversion. In order to realize a high isolation design, the circuits of two PLL and mixer were divided into three independent cavities through a 'T' shape crosser. Based on the techniques of vertical via and inner route for PCB multilayer, almost all of the power distribute network was embedded into inner layer, and the system layout realized a compact and high density design at the principle of shortest RF route. A transition structure of CPWG-SL-CPWG was put forward to interconnect the LO signals which can decline the EM couple. The size of the system board is 14.3mm*lS.2mm*1.3mm, which is much smaller than a traditional product. The isolation between two LO from RF output is 82.6 dB, which agree with the simulation well.
[0006] US2009/0072912A1 titled “Oscillator signal generation with spur mitigation in a wireless communication device”. Techniques for generating oscillator signals in a wireless communication device are described. A phase-locked loop (PLL) may be used to generate an oscillator signal for a selected frequency channel. Different PLL settings may be used for the blocks in the PLL for different frequency channels. Different PLL settings may be for different PLL loop bandwidths, different amounts of charge pump current, different frequency equations associated with different sets of high and low divider ratios, different frequency division schemes associated with different prescaler ratios and/or different integer divider ratios, high side or low side injection for a super-heterodyne receiver or transmitter, and/or different Supply Voltages for one or more circuit blocks such as an Oscillator. A suitable set of PLL settings may be selected for each frequency channel Such that adverse impact due to Spurs can be mitigated.
[0007] Here it is suggested to use different supply voltages for different blocks to mitigate the adverse effect of spurs. VCO may be operated at one of multiple possible supply voltages. A low supply voltage may save power whereas a high supply voltage may increase VCO signal swing, which is useful when spurs are located far away from PLL loop bandwidth. Increased voltage swing may then sharpen the transition edges of the VCO signal and reduce the effects due to the spurs.
[0008] US2004/0209578A1 titled “EMI shield for reducing clock jitter of a transceiver”. A transmitter comprises an oscillator, a phase lock loop, a serializer, and an electrical-to-optical converter. The oscillator is enclosed in a metal shield. The metal shield is soldered to a ground ring of the printed circuit board. In one embodiment, the oscillator is Voltage-controlled oscillator. An apparatus and method for reducing clock jitter on a high speed optical transmitter is described. The transmitter comprises an oscillator, a phase lock loop, a serializer, and an electrical-to-optical converter. The oscillator is enclosed in a metal Shield to reduce the clock jitter. In this embodiment, the metal shield is soldered to a ground ring of a printed circuit board.
[0009] There is still a need of a technical solution which solves the above defined problems and provide an improved system and a method for suppression of power converter switching frequency.

SUMMARY
[0010] This summary is provided to introduce concepts related to generally to DCDC converter switching frequency. The invention more specifically involves a system and a method for suppression of power converter switching frequency in the frequency generator module.
[0011] In an embodiment of the present invention, a system to suppress the switching frequency of the power converter in the frequency generator module is disclosed. The system includes a frequency generator unit that generates an L-band signal by locking its phase with an internal reference signal. Further, a control unit generates a control signal and a frequency generator enabler signal to provide to the frequency generator unit. The system further includes a supply unit generates a plurality of supply voltages required by the frequency generator unit and the control unit, wherein the switching frequency from the supply unit is suppressed by 90dBc.
[0012] In another embodiment of the present invention, the frequency generator unit comprises a reference oscillator that provides the internal reference signal. A frequency generator is integrated with a Voltage-Controlled Oscillator (VCO). The frequency generator generates the L-band signal which is locked to the internal reference signal. It further comprises a signal enhancer that amplifies the internal reference signal for providing sufficient level. Further, a frequency selector selects a required output frequency and to reject unwanted signals.
[0013] In another embodiment of the present invention, the supply unit comprises a noise rejector that suppresses unwanted noise in the supply unit from entering the frequency generator module. It further includes a power converter that converts the main supply into a plurality of lower voltages and a power supply ripple purifier that suppresses the switching frequency from the power converter.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[0014] The detailed description is described with reference to the accompanying figures.
[0015] Figure 1 illustrates a detailed block diagram of a frequency generator module, in accordance with an exemplary embodiment of the present invention.
[0016] Figure 2 illustrates a detailed block diagram of the supply unit, in accordance with an exemplary embodiment of the present invention.
[0017] Figure 3 illustrates a detailed block diagram of the control unit, in accordance with an exemplary embodiment of the present invention.
[0018] Figure 4 illustrates a 3D model of the frequency generator module, in accordance with an exemplary embodiment of the present invention.
[0019] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative methods embodying the principles of the present invention. Similarly, it will be appreciated that any flow charts, flow diagrams, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.

DETAILED DESCRIPTION
[0020] The various embodiments of the present invention describe about a system and a method for suppression of power converter switching frequency in the frequency generator module.
[0021] In the following description, for purpose of explanation, specific details are set forth in order to provide an understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these details. One skilled in the art will recognize that embodiments of the present invention, some of which are described below, may be incorporated into a number of systems.
[0022] However, the systems and methods are not limited to the specific embodiments described herein. Further, structures and devices shown in the figures are illustrative of exemplary embodiments of the presently invention and are meant to avoid obscuring of the present invention.
[0023] Furthermore, connections between components and/or modules within the figures are not intended to be limited to direct connections. Rather, these components and modules may be modified, re-formatted or otherwise changed by intermediary components and modules.
[0024] The appearances of the phrase “in an embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
[0025] It should be noted that the description merely illustrates the principles of the present invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present invention. Furthermore, all examples recited herein are principally intended expressly to be only for explanatory purposes to help the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.
[0026] In an embodiment of the present invention, a system and a method for suppression of power converter switching frequency in the frequency generator module is disclosed.
[0027] In another embodiment of the present invention, a system to suppress the switching frequency of the power converter in the frequency generator module is disclosed. The system includes a frequency generator unit that generates an L-band signal by locking its phase with an internal reference signal. Further, a control unit generates a control signal and a frequency generator enabler signal to provide to the frequency generator unit. The system further includes a supply unit generates a plurality of supply voltages required by the frequency generator unit and the control unit, wherein the switching frequency from the supply unit is suppressed by 90dBc.
[0028] In another embodiment of the present invention, the frequency generator unit comprises a reference oscillator that provides the internal reference signal. A frequency generator is integrated with a Voltage-Controlled Oscillator (VCO). The frequency generator generates the L-band signal which is locked to the internal reference signal. It further comprises a signal enhancer that amplifies the L band signal for providing sufficient level. Further, a frequency selector selects a required output frequency and to reject unwanted signals.
[0029] In another embodiment of the present invention, the supply unit comprises a noise rejector that suppresses unwanted noise in the supply unit from entering the frequency generator module. It further includes a power converter that converts the main supply into a plurality of lower voltages and a power supply ripple purifier that suppresses the switching frequency from the power converter.
[0030] Figure 1 illustrates a detailed block diagram of a frequency generator module, in accordance with an exemplary embodiment of the present invention. The frequency generator module 100 includes a frequency generator unit 200, a control unit 400 and a supply unit 300. The frequency generator module 100 receives supply and generates an L-band signal. The frequency generator module 100 includes a frequency generator unit 202 with integrated VCO which generates the L-band signal and this is locked to an internal reference signal. A reference crystal oscillator 201 is used as an internal reference signal. The signal is amplified using a signal enhancer 203 for providing sufficient level. The harmonic of the signal is rejected using frequency selector 204. The control signals required for the frequency generator is provided by the control unit 400.
[0031] Figure 2 illustrates a detailed block diagram of the supply unit, in accordance with an exemplary embodiment of the present invention. The supply unit includes a noise rejecter 301, a power converter 302 and a power supply ripple purifier 303. The different supply voltages required by the frequency generator unit 200 and the control unit 400 are derived from the supply unit 300 as X1 and X2 respectively. A noise rejecter 301 is added in the path of supply in order to suppress any unwanted noise in supply entering module. A power converter 302 is configured to convert the main supply into lower voltages. The power converter saves power and reduces the module heat up. A power supply ripple purifier 303 is added in the path in order to suppress any noise in the supply path.
[0032] Figure 3 illustrates a detailed block diagram of the control unit, in accordance with an exemplary embodiment of the present invention. The control unit 400 is configured to generate the control signal and the frequency generator enabler signal, both the signals are provided to the frequency generator 202 to generate L-Band signal. The reference signal is generated internally and used as reference to the frequency generator 202. The frequency generator 202 comprises of an integrated VCO synthesizer and a loop selector to generate L-band frequency.
[0033] Figure 4 illustrates a 3D model of the frequency generator module, in accordance with an exemplary embodiment of the present invention. In the 3D model of the frequency generator module 100, multiple layer PCB and housing are mounted. PCB 501 is a multiple layer PCB that consists of the frequency generator, the control unit and the supply unit or the supply circuit. The PCB 501 is fixed to the housing 502 using screws. The power converter 302, which is generating switching frequency is placed on the bottom circuit and rest of the circuit on the top side. The power converter 302 is enclosed in the cavity 503 in the housing 502 as shown in the figure to suppress unwanted radiation.
[0034] In another embodiment of the present invention, the frequency generator unit circuit which is the voltage controlled oscillator (VCO) is a very sensitive device. It can absorb any noise in the surrounding and produce it as spurious at the output or as a phase noise degradation. A steady state voltage needs to be to the Vtune of the VCO. In frequency generator, some common spurs are reference spurs, fractional spurs, spurs from power supply and spur due to any nearby component. In the present module, the power supply spurious has been identified and level reduced. The power converter switching frequency can leak from power supply channel may appear as spur in the module output. The method provided in the present invention is used for suppressing power converter switching frequency leakage into VCO output signal. A single PCB with multiple layer is used for suppressing power converter switching frequency leakage into VCO output signal. And in the multiple layer PCB ensuring ground layer in between the layers controls the spurious by bypassing the spur into the ground. The power planes in the PCB are routed in such a way that sufficient isolation from ground is ensured. To isolate the leakage, power converter has been closed by having a cavity in the housing.
[0035] In another embodiment of the present invention, a compact high density frequency generator module is disclosed, wherein the frequency generator module comprises of frequency generator unit, control unit and supply unit. The supply unit supplies voltages to other units and the control unit generates signal required for frequency generator unit. Frequency generator unit generates signal by locking its phase with reference signal. Frequency generator unit along with signal generates unwanted signal, caused by noise in any other section. These unwanted spurious signals to be suppressed. In the present embodiment, noise from supply unit leaked as unwanted spurious, the methods by which this spurious is suppressed is disclosed.
[0036] In another embodiment of the present invention, the compact frequency generator module 100 generates the L-band signal with frequency generator unit 200 along with the control unit 400, where the switching frequency from the supply unit 300 is suppressed by 90dBc (decibels relative to the carrier).
[0037] In another embodiment of the present invention, the frequency generator unit 200 consists of the reference oscillator 201, the frequency generator 202, the signal enhancer 203 and the frequency selector 204 to generate desired frequency out signal.
[0038] In another embodiment of the present invention, the reference signal is generated internally and used as a reference to the frequency generator 202. The frequency generator 202 comprises of the integrated VCO synthesizer and the loop selector to generate L-band frequency. Further, this signal level is amplified by the signal enhancer 203 and the frequency selector 204 is used to select required output frequency and to reject unwanted signals.
[0039] In another embodiment of the present invention, the control unit 400 generates two signals i.e., the control signal and the frequency generator enabler signal which are provided to the frequency generator 202.
[0040] In another embodiment of the present invention, the supply unit 300 consists of the noise rejecter 301 at the input side for eliminating unwanted noise from external source in supply line. The power converter provides different voltages. The switching frequency from the power converter can be leaked and act as a spurious at the frequency generator module 100 output, a power supply ripple purifier is cascaded to provide high rejection for switching frequency from 302. Different voltages are supplied to the reference oscillator 201, the frequency generator 202 and the control unit 400 for the proper operation.
[0041] In another embodiment of the present invention, in order to suppress the switching frequency from the power convertor 302, physical isolation between the supply unit 300 from the frequency generator unit 200 and the control unit 400 in the compact module is provided by mounting devices on the opposite side of the multiple layer PCB.
[0042] In another embodiment of the present invention, in order to avoid the switching frequency leakage to the frequency output, the power converter is encapsulated in a small cavity 503 in the mechanical housing so that radiated spurious gets absorbed by immediate cavity ground wall.
[0043] In another embodiment of the present invention, the frequency generator module 100 is designed using multiple layers of printed circuit board.
[0044] In another embodiment of the present invention, the stack up of the multiple layers PCB includes a plurality signal layer, a reference ground layer and a non-conductive layer in the first layer, the plurality signal layer, the reference ground layer and the non-conductive layer in the second layer and a plurality supply layer and the reference ground layer in the third layer.
[0045] In another embodiment of the present invention, in the layout routing of the multiple layer PCB, the power planes is routed such that the power converter 302 ground connecting layers are not intersected with any of the power planes.
[0046] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the invention.
, Claims:We Claim :
1. A system to suppress a switching frequency of a power converter in a frequency generator module (100), said system comprising:
a frequency generator unit (200) configured to generate an L-band signal by locking its phase with an internal reference signal;
a control unit (400) configured to generate a control signal and a frequency generator enabler signal to provide to the frequency generator unit (200); and
a supply unit (300) configured to generate a plurality of supply voltages required by the frequency generator unit (200) and the control unit (400), wherein the switching frequency from the supply unit (300) is suppressed by 90dBc.

2. The system as claimed in claim 1, wherein the frequency generator unit (200) further comprises:
a reference oscillator (201) configured to provide the internal reference signal;
a frequency generator (202) integrated with Voltage-Controlled Oscillator (VCO), said frequency generator (202) is configured to generate the L-band signal which is locked to the internal reference signal;
a signal enhancer (203) configured to amplify the L band output signal for providing sufficient level; and
a frequency selector (204) configured to select a required output frequency and to reject unwanted signals.

3. The system as claimed in claim 1, wherein the supply unit (300) further comprises:
a noise rejector (301) configured to suppress unwanted noise in the supply unit (300) from entering the frequency generator module (100);
a power converter (302) configured to convert the main supply into a plurality of lower voltages; and
a power supply ripple purifier (303) configured to suppress the switching frequency from the power converter (302).

4. The system as claimed in claim 1, wherein the frequency generator module (100) is designed using multiple layers of a Printed Circuit Board (PCB).

5. The system as claimed in claim 1 and claim 3, wherein the switching frequency from the power converter (302) is suppressed based on the physical isolation between the supply unit (300) from the frequency generator unit (200) and the control unit (400) in the frequency generator module (100) by mounting the units on opposite side of a multiple layer PCB.

6. The system as claimed in claim 3, wherein the power converter (302) is encapsulated in a small cavity (503) in a mechanical housing to avoid switching frequency leakage to the frequency output.

7. The system as claimed in claim 4, wherein stack up of the multiple layers PCB includes a plurality signal layer, a reference ground layer and a non-conductive layer in the first layer, the plurality signal layer, the reference ground layer and the non-conductive layer in the second layer and a plurality supply layer and the reference ground layer in the third layer.

8. The system as claimed in claim 7, wherein the ground layer is in between the layers in the multiple layer PCB to control the spurious by bypassing the spur into the ground and a plurality of power planes in the PCB are routed in such a way that sufficient isolation from ground is ensured.
Dated this 31st day of March, 2023
For BHARAT ELECTRONICS LIMITED
(By their Agent)

D. MANOJ KUMAR (IN/PA-2110)
KRISHNA & SAURASTRI ASSOCIATES LLP