Designing MRI Equipment

Magnetic resonance imaging (MRI) is a medical imaging technique using radio waves and magnetic fields to create detailed cross-sectional images of internal organs and structures within the body. Widely used in patient analysis and medical diagnosis, MRI often reveals different information about bodily structures than can be visualized using other imaging methods such as X-ray, computed tomography (CT) or ultrasound.

Explore Microsemi's solutions for MRI equipment:

• Component Clocks

• Non-magnetic TVS

• RF PIN Diodes
• RF MosFETS
• Power Modules
• FPGAs and SoCs
• SiC Diodes/FETs
• PCIe Switches
• Ethernet PHYs

Microsemi offers key technologies and services as part of its portfolio to deliver smaller, smarter and more reliable solutions for your medical imaging applications. Our portfolio for MRI equipment designs includes:

• Rubidium Component Clocks: 50% lower power, smallest form factor and highest accuracy over temperature
• Power and RF Discretes: Including SiC Diodes/FETs, discretes and power modules , non-magnetic TVS, RF pin diodes, and RF MosFETs.
• FPGAs and SoCs: Non-volatile, SEU immune, low power, small form factor and secure

Microsemi is well-known for its high-reliability, high-performance solutions. Our medical solutions portfolio is aligned to help you deliver innovative implantable device therapies, diagnostics and monitoring solutions enabling better patient care and quality of life. Contact your local Microsemi sales office today to find the right technologies and products for your medical imaging design needs.

Component Clocks: RF Oscillators for MRI Equipment

Magnetic resonance imaging (MRI) equipment requires a local reference oscillator, in order to serve as a source for all the RF components in the multiple MRI circuit boards. Microsemi's Rubidium MAC (Miniature Atomic Clock) is ideal for medical imaging applications to serve as this local reference oscillator.

Rubidium MAC Advantages for MRIs

• MRIs require an accurate and a stable reference source
• Low power consumption and size help reduce the footprint
• Better accuracy reference results in less frequent calibration of the customer system

Feature	MAC	Traditional Rubidium
Size	Smaller	Larger
Power	5 W @ 25ºC	~10W : ~2X MAC
Frequency Stability	No hops & pops	Hop & pops
TEMPCO	Better	Worse
Accuracy (10 MHz)	<0.0005 Hz	<0.0005 Hz

Ready to learn more? Contact your local Microsemi sales office today to find the right technologies and products for your medical imaging design needs.

SiC Diodes/FETs for MRI Power Conversion

Silicone Carbide (SiC) Schottky Diodes and MosFETs offer superior dynamic and thermal performance over conventional silicon power diodes and MosFETs. The table below summarizes the advantages of SiC vs Si power discretes.

Characteristics	SiC vs. Si	Results	Benefits
Breakdown Field	10x Higher	Lower On-Resistance	Higher efficiency
Band Gap	3x Higher	Higher operating temperature	Improved cooling
Thermal conductivity	3x Higher	Higher power density	Higher current capabilities
Positive Temperature coefficient	-	Self regulation	Easy paralleling
Temperature Independent switching behavior	-	Stable high temperature performance	Lower losses
Almost no Reverse Recovery charge	-	Lower switching losses Higher switching capabilities	Higher performance

Microsemi SiC Schottky Diode Advantages

• Superior Passivation Technology: leads to higher reliability. Microsemi thin film passivation applied in the wafer fab vs. competitors’ spin on passivation applied post wafer fab.
• Patented Technology: Junction barrier structure has a lower VF than any equivalent die size (due to larger Schottky area and buried P-Wells).

Microsemi SiC MosFETs Advantages

• Best in Class R_DS(on) vs Temperature: leads to lower switching losses as well as stability over the complete operating temperature range.
• Longest Short Circuit Withstand Rating: highest simple easy control circuit design

Microsemi also manufactures SiC Schottky Diode Modules and SiC MosFET Modules, which allow higher integration and lower time to market.

SiC Documentation

•  SiC Products Brochure

Ready to learn more? Contact your local Microsemi sales office today to find the right technologies and products for your medical imaging design need

Power Modules

Microsemi's Power Modules products are a great fit for several MRI subsystems, including Gradient Amplifiers (phase leg IGBTs, as well as buck or boost), AC rectifier Bridges (Diode modules) and high power liner regulators (MOSFET modules). To select the best Microsemi Power Module for MRI power sub-systems, please chose from the selection tables below.

Chopper & Phase Leg IGBT Modules

VCES (V)	IGBT type	IC (A) Tc=80C	VCE(on) (V) at rated IC	Package	NTC	BOOST	BUCK	PHASE LEG
1200	NPT FAST	300	3.2	SP6	option	APTGF300DA120G	APTGF300SK120G	APTGF300A120G
		300	3.2	D3	option	APTGF300DA120D3G	APTGF300SK120D3G	APTGF300A120D3G
	TRENCH 4	90	1.85	SP1	YES	APTGL90DA120T1G	APTGL90SK120T1G	APTGL90A120T1G
		180	1.85	SP3	YES	N/A	N/A	APTGL180A120T3AG
		325	1.85	D3	option	APTGL325DA120D3G	APTGL325SK120D3G	APTGL325A120D3G
		475	1.85	D3	option	APTGL475DA120D3G	APTGL475SK120D3G	APTGL475A120D3G
		700	1.85	D3	option	APTGL700DA120D3G	APTGL700SK120D3G	N/A
	TRENCH 4 FAST	100	2.05	SP3	YES	N/A	N/A	APTGLQ100A120T3AG
		400	2.05	SP6	YES	N/A	N/A	APTGLQ400A120T6G

IGBT Module Technology Selection

Technology	Module code	600V	650V	1200V	Switching losses	Conduction losses	Hard switching	Soft Switching
NPT FAST	APTGFxxxx	150°C	N/A	150°C	low	Very high ~3.0V	<50kHz	<100kHz
NPT MOS8	APTGRxxxx	N/A	N/A	150°C	low	High ~2.5V	<50kHz	<100kHz
TRENCH4	APTGLxxxx	N/A	175°C	175°C	Medium	Moderate ~1.8V	<40kHz	<80kHz
TRENCH4 FAST	APTGLQxxxx	N/A	175°C	175°C	Moderate	Medium ~2.0V	<50kHz	<100kHz

Standard Recovery Rectifier Modules

Prefix	Circuit	VRRM	IF	Package
MSD = 30mm height MSDM = Low Profile SM2-1 = 22mm SM3-1 = 17mm		800V 1200V 1600V 1800V	30A to 50A	SM1
			52A to 75A	SM2-1 SM2
			100A to 200A	SM3-1SM3
MKSD			36A to 120A
				SD1
MSAD
			165A to 200A	SD2
MSCD

Single and Dual MOSFET Modules for Linear Regulators

VDSS(V)	MOSFET type	RDS(on) (mΩ)	Shunt resistor (mR)	Package	NTC
100	MOS 5	9	4.4	SP1 or SP3	YES	APTML10UM09R004T1AG	APTML102UM09R004T3AG
200		18	10		YES	APTML20UM18R010T1AG	APTML202UM18R010T3AG
500	MOSFET  LINEAR	90	20		YES	APTML50UM90R020T1AG	APTML502UM90R020T3AG
600		125	20		YES	APTML60U12R020T1AG	APTML602U12R020T3AG
1000	MOS 4 LINEAR	600	20		YES	APTML100U60R020T1AG	APTML1002U60R020T3AG

Non Magnetic TVS: Data Integrity in MRIs

Data lines are susceptible to transient surges, and TVS arrays are typically used to suppress these transient surges. In MRIs (large magnetic field) the material used to construct TVS arrays can also be affected, reducing their effectiveness. Traditional TVS Arrays use the copper alloy A194 to make leads stiffer, which is unacceptable in harsh magnetic environments. Microsemi's Non-Magnetic TVS arrays use a different alloy, with 0% iron content, and full compatibility with MRIs. In order to deal with the inherent higher flexibility of the non-magnetic alloy, compared to Iron, Microsemi's non-Magetic TVS arrays use a QFN143 package, which is 100% compatible with the traditional SOT143. In a QFN143 package, the epoxy case prevents the leads from bending. All USBQNM504xxx TVS Arrays support 500W (8/20us pulse), protecting a single line.

Non-Magnetic TVS array selection table

Product	Marking	Max Stand off Voltage, Vwm(V)	Min Breakdown Voltage, Vbr V(BR)  @1mA	Max Clamping Voltage, Vcl(VC)@1A	Max Clamping Voltagge, Vcl(VC)@5A	Max Standby Current, Id(ID)@Vwm	Max Capacitance C(pF) @0V&1MHz	Max Temperature Coefficienct of Vbr. alphavbr (αV(BR)	Type
USBQNM50403E3	N03	3.3	4.0	8.0	11	200	3	-5	Unidirectional
USBQNM50405E3	N05	5.0	6.0	10.8	12	40	3	1	Unidirectional
USBQNM50412E3	N12	12.0	13.3	19.0	26	1	3	8	Unidirectional
USBQNM50415E3	N15	15.0	16.7	24.0	32	1	3	11	Unidirectional
USBQNM50424E3	N24	24.0	26.7	43	57	1	3	28	Unidirectional
USBQNM50403CE3	N03C	3.3	4.0	8.0	11	200	3	-5	Bidirectional
USBQNM50405CE3	N05C	5.0	6.0	10.8	12	40	3	1	Bidirectional
USBQNM50412CE3	N12C	12.0	13.3	19.0	26	1	3	8	Bidirectional
USBQNM50415CE3	N15C	15.0	16.7	24.0	32	1	3	11	Bidirectional
USBQNM50424CE3	N24C	24.0	26.7	43	57	1	3	28	Bidirectional

All USBQNM504xxx TVS Arrays support 500W (8/20us pulse), protecting a single line.

Ready to learn more? Contact your local Microsemi sales office today to find the right technologies and products for your medical imaging design needs.

RF PIN Diodes for MRI

Radio-frequency (RF) coils, known also as RF resonators and
RF probes, are essential components in a MRI system. PIN diodes are used as switching elements in MRI coil switches. Selecting the right PIN diodes for your MRI coils plays a key role in the quality of the resultant MRI images. Microsemi's leading RF PIN diode portfolio is engineered to meet your equipment design needs.

Volume/Bird Cage Coils: Switching Diodes

End ring resonant/anti-resonant Switching Diodes

Product	MRI Usage	notes
HUM2020	1.5T: 32 diodes/body coil 3.0T:64 diodes/body coil 7.0T: 64+ depending on design For diode choice, see the MRI PIN Diodes Selection Guide	Low Magnetic not required
HUM3004		Low Magnetic not required
HUM4020		Low Magnetic not required

Surface Coils: Receive Array PIN Diodes

Loop Array or Strip Array: 4 channels and N x 4 channels

Product	Usage	Notes
UM7201	Depends on design. 4-16 diodes/array For diode choice, see the MRI PIN Diodes Selection Guide	Low Magnetic (for >1.5T)
UM9601		Low Magnetic (for >1.5T)
UM9701		Low Magnetic (for >1.5T)
UM9989AP		Low Magnetic
UM9995		Low Magnetic
UMX5601		Ultra Low Magnetic
UMX5101		Ultra Low Magnetic
MPS2R10-606		SP2T Switch

Transmit/Receive Control Boards

Product	MRI Usage	Notes
UM4001	T/R Control Circuits 16 diodes/machine (typical) For diode choice, see the MRI PIN Diodes Selection Guide
UM4301		Low Magnetic not required
UM7301		Low Magnetic not required
UM7101		Low Magnetic not required
UM6201		Low Magnetic not required

Receiver Protection Circuits

Product	MRI Usage	Notes
UM9989	RF Receive circuits (not in 'Bore") 2 diodes/channel 2-16 channels depending on design For diode choice, see the MRI PIN Diodes Selection Guide	Low Magnetic not required
UM7201		Low Magnetic not required

MRI RF PIN Diodes Application Notes

•  Analysis of NMR/MRI Coils using PIN Diode Switches

RF MosFETs for Magnetic Resonance Imaging

In MRIs, the Larmor Frequency determines the choice of the RF MosFET used in the RF amplifier, according to the MRI field strength.

MRI RF Amplifier MosFET Selection Table

MRI Field Strength	Larmor frequency of the 1H molecule	P/N	Freq Max	Output Power	Package	Pinout
1.0T	42.56MHz	ARF468AG	45MHz	300W	TO-264	Main
		ARF468B/G	45Mhz	300W		Alternate
1.5T	64.00MHz	ARF460AG	65MHz	150W	TO-247	Main
		ARF460BG		150W		Alternate
		ARF477FL	100Mhz	400W	Custom 8-pin 1.5x0.57
3.0T	128.00MHz	ARF475FL	150Mhz	450W	Custom 8-pin 1.5x0.57	Main
		ARF476FL	150Mhz	450W		Alternate
		ARF479

MRI RF RF Amplifier MosFET Application Notes

•  ARF475FL, 128 MHz Pulse Amplifier in a 3T MRI application

Ready to learn more? Contact your local Microsemi sales office today to find the right technologies and products for your medical imaging design needs.

FPGAs in Medical Imaging

FPGAs find their usage across most of the medical imaging functions in a wide range of medical equipment’s such as CT Scans, MRIs, 3D Ultrasounds and X-Ray machines. Microsemi’s SoCs and FPGAs with their unique differentiating factors provide an ideal solution for medical applications such as Human Machine Interface (HMI), displays, frame grabbing, video capture and Image processing.

Microsemi FPGA Differentiating Factors in Medical Imaging

• Reliability with Non-Volatile Memory
• Safety/security heritage
• Low power, instant-on
• Long life cycles
• No external configuration device required

FPGA Medical Imaging Functions

• Human Machine Interface  (HMI)
• Display control
• Video capture / Frame grabbing
• Thermal infrared imaging
• System control
• Analytics

For more information on FPGA based Imaging/Video solutions visit Imaging/Video

Medical Imaging FPGA Application Briefs

• AC369: FPGA Solutions for Ultrasound
• AC370: FPGA Solutions for 4D Imaging-based Therapy

Solectrix SXoM-SF2 is a high performance, low power, secure and ultra-compact DSP SOM solution based on SmartFusion2 SoC FPGA devices is ideally suited for medical imaging application due to its DSP and high-speed PCIe streaming.

Ready to learn more? Contact your local Microsemi sales office today to find the right technologies and products for your medical imaging design needs.

Feature

MAC

Traditional Rubidium

Size

Smaller

Larger

Power

5 W @ 25ºC

~10W : ~2X MAC

Frequency Stability

No hops & pops

Hop & pops

TEMPCO

Better

Worse

Accuracy (10 MHz)

<0.0005 Hz

<0.0005 Hz

Characteristics

SiC vs. Si

Results

Benefits

Breakdown Field

10x Higher

Lower On-Resistance

Higher efficiency

Band Gap

3x Higher

Higher operating temperature

Improved cooling

Thermal conductivity

3x Higher

Higher power density

Higher current capabilities

Positive Temperature coefficient

-

Self regulation

Easy paralleling

Temperature Independent switching behavior

-

Stable high temperature performance

Lower losses

Almost no Reverse Recovery charge

-

Lower switching losses

Higher switching capabilities

Higher performance

V_CES (V)

IGBT type

I_C (A) Tc=80C

V_CE(on) (V) at rated I_C

Package

NTC

BOOST BUCK PHASE LEG

1200

NPT FAST

300

3.2

SP6

option

APTGF300DA120G

APTGF300SK120G

APTGF300A120G

300

3.2

D3

option

APTGF300DA120D3G

APTGF300SK120D3G

APTGF300A120D3G

TRENCH 4

90

1.85

SP1

YES

APTGL90DA120T1G

APTGL90SK120T1G

APTGL90A120T1G

180

1.85

SP3

YES

N/A

N/A

APTGL180A120T3AG

325

1.85

D3

option

APTGL325DA120D3G

APTGL325SK120D3G

APTGL325A120D3G

475

1.85

D3

option

APTGL475DA120D3G

APTGL475SK120D3G

APTGL475A120D3G

700

1.85

D3

option

APTGL700DA120D3G

APTGL700SK120D3G

N/A

TRENCH 4 FAST

100

2.05

SP3

YES

N/A

N/A

APTGLQ100A120T3AG

400

2.05

SP6

YES

N/A

N/A

APTGLQ400A120T6G

Technology Module code 600V 650V 1200V Switching losses Conduction losses Hard switching Soft Switching NPT FAST APTGFxxxx 150°C N/A 150°C low Very high
~3.0V <50kHz <100kHz NPT MOS8 APTGRxxxx N/A N/A 150°C low High
~2.5V <50kHz <100kHz TRENCH4 APTGLxxxx N/A 175°C 175°C Medium Moderate
~1.8V <40kHz <80kHz TRENCH4 FAST APTGLQxxxx N/A 175°C 175°C Moderate Medium
~2.0V <50kHz <100kHz Prefix Circuit V_RRM I_F Package MSD = 30mm height
MSDM = Low Profile
SM2-1 = 22mm
SM3-1 = 17mm    800V
1200V
1600V
1800V  30A to 50A  SM1 52A to 75A SM2-1 SM2 100A to 200A SM3-1SM3  MKSD     36A to 120A     SD1  MSAD   165A to 200A  SD2   MSCD  

VDSS(V)

MOSFET type

RDS(on) (mΩ)

Shunt resistor (mR)

Package

NTC

   

100

MOS 5

9

4.4

SP1 or SP3

YES

 APTML10UM09R004T1AG

 APTML102UM09R004T3AG

200

18

10

YES

 APTML20UM18R010T1AG

APTML202UM18R010T3AG

500

MOSFET  LINEAR

90

20

YES

APTML50UM90R020T1AG

APTML502UM90R020T3AG

600

125

20

YES

 APTML60U12R020T1AG

APTML602U12R020T3AG

1000

MOS 4 LINEAR

600

20

YES

APTML100U60R020T1AG

APTML1002U60R020T3AG

Product Marking Max Stand off Voltage, Vwm(V) Min Breakdown Voltage, Vbr V_(BR)
 @1mA Max Clamping Voltage, Vcl(V_C)@1A Max Clamping Voltagge, Vcl(V_C)@5A Max Standby Current, Id(I_D)@Vwm Max Capacitance C(pF) @0V&1MHz Max Temperature Coefficienct of Vbr. alphavbr (α_V(BR) Type USBQNM50403E3 N03 3.3 4.0 8.0 11 200 3  -5 Unidirectional USBQNM50405E3 N05 5.0  6.0  10.8  12  40  3  1  Unidirectional USBQNM50412E3 N12 12.0  13.3  19.0  26 1  3  8  Unidirectional USBQNM50415E3  N15 15.0  16.7  24.0  32  1  3  11  Unidirectional USBQNM50424E3  N24 24.0  26.7  43  57  1  3  28  Unidirectional USBQNM50403CE3 N03C 3.3 4.0 8.0 11 200 3  -5 Bidirectional USBQNM50405CE3  N05C 5.0  6.0  10.8  12  40  3  1  Bidirectional USBQNM50412CE3 N12C 12.0  13.3  19.0  26 1  3  8  Bidirectional USBQNM50415CE3  N15C 15.0  16.7  24.0  32  1  3  11  Bidirectional USBQNM50424CE3  N24C 24.0  26.7  43  57  1  3  28  Bidirectional Product MRI Usage notes HUM2020 1.5T: 32 diodes/body coil
3.0T:64 diodes/body coil
7.0T: 64+ depending on design
For diode choice, see the MRI PIN Diodes Selection Guide Low Magnetic not required HUM3004 Low Magnetic not required HUM4020 Low Magnetic not required Product Usage Notes UM7201 Depends on design.
4-16 diodes/array
For diode choice, see the MRI PIN Diodes Selection Guide  Low Magnetic (for >1.5T) UM9601 Low Magnetic (for >1.5T) UM9701 Low Magnetic (for >1.5T) UM9989AP Low Magnetic UM9995 Low Magnetic UMX5601 Ultra Low Magnetic UMX5101 Ultra Low Magnetic MPS2R10-606 SP2T Switch Product MRI Usage Notes UM4001  T/R Control Circuits
16 diodes/machine (typical)
For diode choice, see the MRI PIN Diodes Selection Guide
     UM4301 Low Magnetic not required UM7301 Low Magnetic not required UM7101 Low Magnetic not required UM6201 Low Magnetic not required Product MRI Usage Notes UM9989 RF Receive circuits (not in 'Bore")
2 diodes/channel
2-16 channels depending on design
For diode choice, see the MRI PIN Diodes Selection Guide Low Magnetic not required UM7201 Low Magnetic not required MRI Field Strength Larmor frequency of the 1H molecule P/N Freq Max Output Power Package Pinout 1.0T 42.56MHz ARF468AG 45MHz 300W TO-264 Main ARF468B/G 45Mhz 300W Alternate 1.5T 64.00MHz ARF460AG
65MHz 150W TO-247 Main ARF460BG 150W Alternate ARF477FL 100Mhz 400W Custom
8-pin 1.5x0.57   3.0T 128.00MHz ARF475FL 150Mhz 450W Custom
8-pin 1.5x0.57 Main ARF476FL 150Mhz 450W Alternate ARF479