Supertex inc. MD2131DB1 MD2131 Ultrasound Beamforming Transmitter Demoboard Introduction General Description The integrated circuit (IC) consists of the CMOS digital logic input circuits, an 8-bit current DAC for the waveform amplitude control, and four PWM current sources. These current sources are constructed with the high speed in-phase and quadrature current switch matrix and the built-in sine and cosine angle-to-vector look-up table. The angular resolution of the vector table is 7.5 degrees per step with a total range of 48 steps. There are four logic input signals to control the inphase and quadrature PWM push-pull current source’s output timing frequency cycle in the burst and waveform envelope. The MD2131DB1 circuit uses two depletion-mode MOSFETs in the push-pull mode to drive the center tapped, wide band, ultrasound output transformer. The two depletion-mode MOSFETs are packaged in a single 5x5mm DFN package. The sources of the MOSFETs are directly driven by the MD2131’s two outputs, whose maximum peak sinking current is up to 3.0A. These current source outputs are controlled by the MD2131’s internal angular vector switch matrix and the in-phase and quadrature PWM input signals. The MD2131 is a high speed, arbitrary waveform, push-pull source driver. It is designed for medical ultrasound imaging and HIFU beamforming applications. It also can be used in NDT, sonar and other ultrasound phase-array focusing beamforming applications. The MD2131’s output stage is designed to drive two depletion mode, high voltage, Supertex DN2625 MOSFETs as a source driver. The MOSFET drains are connected to a center-tapped ultrasound frequency pulse transformer. The secondary winding of the transformer can connect to the ultrasound piezo or capacitive transducer via a cable with a good impendence match. The MD2131 has a high speed serial data interface that quickly updates the data register’s per-scan-line for changing the beamforming phase angles and apodization amplitudes. This MD2131DB1 datasheet describes how the demoboard is to used to generate the ultrasound transmit beamforming waveform with the Gaussian profile, and the adjustable frequency, amplitude and phase angle. It also provides information about how to design a user application circuit and PCB using the Supertex MD2131 and DN2625 devices. All of the MD2131’s logic control signals are generated by two small CPLD programmable logic circuits clocked by an on-board 160MHz crystal oscillator. The CPLD circuits not only generate accurate timing for the high speed PWM control waveforms, but also the serial data and clock to set and change the waveform amplitude DAC and phase angle data registers. The external clock input can be used if the on-board oscillator is disabled. The external trigger input can be used to synchronize the burst waveforms’ launch timing. There are five push buttons for enabling and selecting the output wave- Demoboard Block Diagram +3.3V VCC EXTRG VCCIO EXTRG CPLD EXCLK OSC 160MHz +2.5V JTAG CLKIN DIS Wave Freq Ampl Phase ENA Doc.# DSDB-MD2131DB1 A070114 EN IA QA IB QB SDI SDO SCK CS LD PHO DAC PWR EN +2.5V +5.0V VLL VDD PA MD2131 GND RFB PB +5.0V +3.3V DN2625 +70 to 100V VPP C7 DN2625 T1 1:1:1 JUMP 220pF XDCX 1k LOAD +5.0V +3.3V Supertex inc. www.supertex.com MD2131DB1 possible. The supply voltage bypass capacitors and the MOSFET gate decoupling capacitors should be as close to the pins as possible. The capacitor’s ground pin pads should have low inductance feed-through connections that are connected directly to a solid ground plane. The VDD and VPP supplies can draw fast transient currents of up to 3.5A, so they should be provided with a low impedance bypass capacitor at the chip’s pins. A ceramic capacitor of 0.1 to 1.0µF may be used. Minimize the trace length to the ground plane, and insert a ferrite bead in the power supply lead to the capacitor to prevent resonance in the power supply lines. For applications that are sensitive to jitter and noise and using multiple MD2131 ICs, insert another ferrite bead between VDD, and decouple each chip supply separately. Pay particular attention to minimizing trace lengths and using sufficient trace width to reduce inductance, not only on the supply pins but also on the CA/B and KA/B compensation pins. Very closely placed surface mount components are highly recommended. Be aware of the parasitic coupling from the high voltage outputs to the input signal terminals of MD2131. This feedback may cause oscillations or spurious waveform shapes on the edges of signal transitions. Since the input operates with signals down to 2.5V, even small coupling voltages may cause problems. The use of a solid ground plane and good power and signal layout practices will prevent this problem. Also ensure that the circulating ground return current from a capacitive load cannot react with common inductance to create noise voltages in the input logic circuitry. form frequency, phase angle and amplitude. Four color LEDs indicate the power, chip enable and wave-form parameter selection states. The MD2131DB1 output waveform can be displayed by using an oscilloscope and the high impedance probe at the TP13 test point. It also can use an SMA to BNC, 50Ω, coaxial cable to directly connect to an oscilloscope, with an attenuation of 5:1 if R10 is 200Ω. A cable can also be used to directly drive the user’s transducer. Jumper J4 can be used to select whether or not to connect the on-board equivalent load, which is formed by a 220pF capacitor in parallel with a 1.0kΩ resistor. Circuit Design & PCB Layout The thermal pad at the bottom of the MD2131 package must be connected to the VSUB pin on the PCB. The VSUB is connected to the IC’s substrate. It is important to make sure that the VSUB is well grounded. A proper supply voltage power-up sequence is needed to test the circuit. To prevent any supply voltage polarity reversing, the circuit also has the protection of Schottky diodes D7, D8 and D9. Due to the high current and high current slew rate nature of this common gate, source driven and push-pull circuit topology, the two cascading N-channel MOSFETs need to have very low lead inductance. The DN2625DK6 MOSFET is designed for this application and works seamlessly with the MD2131K7. In particular, a good PCB layout design needs to shorten the traces between the MD2131K7 output pins and DN2625DK6 source pins. It is also necessary to connect all three pairs of pins between them for the high current carrying capacity. Furthermore, because of the high di/dt in the output current of the MD2131, it is also necessary to have the Schottky diodes D5 and D6 from the driver output pins to the +5.0V power supply line as the clamping diodes. Note that the diodes must have enough speed and peak current capability. The RC snubber circuits of R8-C5 and R15-C28 at the output pins can dump the current pulse edge ringing effectively. This MD2131DB1 beamforming demoboard should be powered up with multiple DC power supplies with current limiting functions. The power supply voltages and current limits used in the testing are listed on page 11. There are examples of the MD2131DB1 demoboard input and output waveform and measurements shown in Figures 1 to 9. Output Transformer Design A center tapped wide band ultrasound transformer is needed for the push pull output circuit. The transformer serves at least three functions: the balanced differential to single end RF output transformer; the isolation barrier to the ultrasound probe; and the impedance matching or low pass net work combined with the cable and transducer element. The MD2131 PWM clock may operate at a 40 to 160MHz frequency range, however the wide band transformer only needs to work in the frequency band of the ultrasound being transmitted. Beside the bandwidth consideration, the transformer also needs enough peak current capacity and RF power coupling efficiency to make sure the ferrite magnetic core will not be saturated, have little leakage inductance and will be a small size. PCB designers need to pay attention to some of the connecting traces as high voltage and high speed traces. In particular, low capacitance to the ground plane and more trace spacing need to be applied in this situation. High speed PCB trace design practices that are compatible with operating speed of about 100 to 200 MHz are used for the demo board PCB layout. The internal circuitry of the MD2131 can operate at quite a high frequency, with the primary speed limitation being load capacitance. Because of this high speed, and the high transient currents that result when driving even very small inductive loads, ringing and even oscillations are Doc.# DSDB-MD2131DB1 A070114 2 Supertex inc. www.supertex.com 3 MH2 B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 3 2 J3 EXTRG 2 R7 50 TP2 TP3 CC DD EE FF GG HH II JJ KK LL MM NN MH3 36 40 32 29 28 33 8 38 42 1 41 34 1 MH4 VCC U3 XC9572XL_VQ44 NC1 NC2 NC3 NC4 NC5 37 PH0 DAC PWR MH1 10 TMS 9 TDI2 24 TDO2 11 TCK R2 50 AA 44 2 1 C8 0.1 C7 0.1 C29 0.1 16 23 14 13 22 3 SDI SDO SCK CS LD EN TP20 VCC OUT GND 18 NC9 NC8 20 19 NC7 21 NC6 12 EN C6 0.1 2 X1 FXO-HC73-160 1 4 EN VCC SDI SDO SCK CS LD VCCIO 39 EXTRG CLKIN 43 31 LED1 30 LED2 27 PWR 35 VCC 15 VCC 26 2 3 5 6 7 BB 4 GND 17 GND 25 GND J2 EX = 0 SW1 R1 1k B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 36 40 32 29 28 33 8 38 42 1 41 34 C1 0.1 VLL VCC C31 0.1 R17 33k R22 200 R18 33k R23 200 C D E F G H I J K L M N TP4 TP5 37 B 44 D4 YLW VCC U2 XC9572XL_VQ44 A 4 GND 17 GND 25 GND SW3 10 TMS 9 24 TDI1 TDO1 11 TCK J6 JTAG R3 1k D1 YLW C10 0.1 23 16 R4 1k D2 RED R5 1k D3 GRN D7A D7B VDD LD CS SCK SDO SDI EN EN 21 EN 15 IB 13 QB 14 IA 12 QA C12 0.1 TP21 VLL C24 0.1 R14 200 3 + R27 0 J7 + C33 10 16V U4 2 LM4040 1 (+3.3V) (+5.0V) VCC VGG VDD C32 10 16V VDD TP1 PWR R6 1k TP15 11 SDI TP10 18 SDO TP14 10 SCK TP18 19 CS TP16 20 LD 9 DGND TP6 TP12 TP7 TP9 TP8 C11 0.1 DAC C20 0.1 13 14 VCC U V X Y Z 22 18 IB 20 QB 19 IA 21 QA 12 EN C9 0.1 PH0 1 2 3 4 5 6 1 SW2 C30 0.1 R25 200 R19 33k R24 200 C37 0.1 SW4 2 3 5 6 7 R20 33k SW5 R21 33k R26 200 C35 0.1 1 2 1 39 EXTRG 43 CLKIN 31 NC12 30 NC11 27 NC10 C38 0.1 1 2 6 3 WAV FRE PHASE AMPL ENA 1 2 35 VCC 26 VCC 15 VCC 1 2 4 C2 0.1 C13 27nF C3 0.1 C4 0.1 U1 MD2131K7 C14 27nF VDD D9 B1100-13 R16 49.9k D8A C26 27nF C25 27nF 41 VSUB 4 GND 2 GND 8 VLL VREF 22 RFB 23 6 1 17 AGND 1 2 3 4 5 VDD VDD VDD 16 5 26 7 GND 6 C3A GND 24 C2B 31 3 VDD TP17 TP11 PA 1 R8 1.0 1W M1B DN2625DK6 D5B 7 8 9 10 11 12 C16 0.1 C5 3.3nF VDD C36 1µ 100V (+70 to 100V) VPP C21 27nF C27 0.1 3 VCC C22 0.1 C28 3.3nF R15 1.0 1W 16 15 14 13 34 PB M1A 6 33 PB PB DN2625DK6 32 5 PB 3 D6A D6B 29 GND 27 GND 36 VSUB 35 VSUB 39 PA 38 PA PA 37 D5A C15 27nF C39 0.1 C1B 40 C2A C3B 25 1 2 1 1 KA C1A KB 28 1 6 3 4 4 3 30 2 Doc.# DSDB-MD2131DB1 A070114 6 3 R12 100 1W 1 R9 100 1W 3 2 5 4 1 C34 10 16V 2 OUT1 4 OUT2 7 6 10 OUTPUT 9 J4 + 2 4 R28 0 TP19 C19 220p 250V 1 3 OUT1 T1 EP10_EP13 TP13 U5 ADP3339AKC-2.5RL7 IN C23 0.1 (+3.3V) VGG D2 VPP R11 0 C18 1µ 100V D1 C17 0.1 (+3.3V) VGG 4 3 D8B (+2.5V) VLL R13 1k 1W R10 200 1 3 2 J5 XDCR-A Circuit Schematic 4 J1 EXCLK MD2131DB1 Supertex inc. www.supertex.com MD2131DB1 PCB Layout MD2131DB1 Actual Dimensions: 10.2cm x 7.6cm (4.00” x 3.00”) Doc.# DSDB-MD2131DB1 A070114 4 Supertex inc. www.supertex.com MD2131DB1 MD2131DB1 Input and Output Waveforms Figure 1: The output waveforms of 16-sample/cycle at 10MHz, 135deg, DAC = 255, VPP = 100V, 220pF//1kΩ load. Figure 2: The output waveforms of 8-sample/cycle at 10MHz, 45deg, DAC Range = 4 - 68, VPP = 100V, 220pF//1kΩ load. Doc.# DSDB-MD2131DB1 A070114 5 Supertex inc. www.supertex.com MD2131DB1 Figure 3: The output waveforms of phase angle 0, 15, 30 … 75 deg. Figure 4: The output waveforms of phase angle 0, 45, 90… 255 deg. Doc.# DSDB-MD2131DB1 A070114 6 Supertex inc. www.supertex.com MD2131DB1 MD2131DB1 10MHz Phase Angle Every 15O 360 330 300 270 Degrees 240 210 180 150 120 90 60 30 0 0 4 8 12 16 20 24 28 32 36 40 44 48 Angle Step Figure 5: The phase angle measurements of 10MHz, 15deg/step from 24 traces of 10,000 data points FFT. The maximum MD2131 phase angular resolution is 7.5deg. Figure 6: The 10MHz 16 sample/cycle output waveform and FFT (Math) results at 10MHz and harmonics, 220pF//1.0kΩ load. Doc.# DSDB-MD2131DB1 A070114 7 Supertex inc. www.supertex.com MD2131DB1 Figure 7: Input IA, IB, QA, QB and load waveform of RF 13.3MHz, 12-sample/cycle, 160MHz PWM. Figure 8: Input IA, IB, QA, QB and load waveform of RF 10MHz, 16-sample/cycle, 160MHz PWM. Doc.# DSDB-MD2131DB1 A070114 8 Supertex inc. www.supertex.com MD2131DB1 Figure 9: Input IA, IB, QA, QB and load waveform of RF 8.0MHz, 20-sample/cycle, 160MHz PWM.. Output Waveform Frequency Selection Table Samples / Cycle of Ultrasound Output Waveform Output Frequency 12 s/c 16 s/c 20 s/c Frequency 13.3MHz 10.0MHz 8.0MHz Note: fCLKIN = 160MHz Output Waveform Phase Angle Selection Table Phase Angle Steps (PHASE Button) 0 1 0 (power on, LED1 on) 7.5 ... ... 24 ... ... 180 47 48 352.5 360 Note Output Phase Angle Degree Output Waveform Amplitude Selection Table Amplitude Steps (AMPL Button) 0 1 0 16 Doc.# DSDB-MD2131DB1 A070114 ... ... 8 ... ... 128 (power on, LED2 on) 9 15 16 240 255 Note DAC Register Value Supertex inc. www.supertex.com MD2131DB1 Board Connector and Test Pin Description CPLD Pin # Signal Name Description U2, 3 - 15, 26, 35 VCC CPLD logic power supply +3.3V U2, 3 - 26 VLL CPLD, VCCIO and MD2131 logic power supply +2.5V U2, 3 - 4, 17, 25 GND Logic power ground 0V U2 - 2 WAV Run or stop demo waveform phase U2 - 3 FRE Selecting frequency: 8,10 and 13.3MHz U2 - 5 PHASE Single step phase change, angle stepping:0, 7.5, 15…360 U2 - 6 AMPL Single step amplitude change, DAC stepping: 15, 31…255 U2 - 7 ENA U2 - 18 IA Output signal to MD2131 IA U2 - 19 IB Output signal to MD2131 IB U2 - 20 QA Output signal to MD2131 QA U2 - 21 QB Output signal to MD2131 QB U3 - 31 LED1 Output signal yellow, PH0 LED is on when phase = 0 U3 - 30 LED2 Output signal yellow, DAC LED is on when DAC = 127 U3 - 27 PWR Output signal LED green, indicates +3.3V power supply on U2, 3 - 10 TMS Test mode select of JTAG U2, 3 - 9 TDI Test data in of JTAG, two CPLD in daisy chain U2, 3 - 24 TDO Test data out of JTAG, two CPLD in daisy chain U2, 3 - 11 TCK Test clock of JTAG U2, 3 - 43 CLK CPLD clock input U2, 3 - 39 EXTRG U2, 3 - 12 EN Output signal LED red, indicates MD2131 is enabled U3 - 22 SDI Output signal to MD2131 SDI U3 - 16 SDO Input signal from MD2131 SDO U3 - 23 SCK Output signal to MD2131 SCK U3 - 14 CS Output signal to MD2131 CS U3 - 13 LD Output signal to MD2131 LD All remaining pins Doc.# DSDB-MD2131DB1 A070114 Control MD2131 EN pin External trigger signal input to control waveform timing NC or Reserved 10 Supertex inc. www.supertex.com MD2131DB1 CPLD Programming Connector JTAG Pin # Signal Name Description J6 - 1 TMS Test mode select of CPLD J6 - 2 TDI Test data In of CPLD J6 - 3 TDO Test data out of CPLD J6 - 4 TCK Test clock of CPLD J6 - 5 GND Logic power supply ground 0V for programming only J6 - 6 VCC Logic power supply +3.3V for programming only Test Signal Connector SMA & Jumper Signal Name Description External clock input when on-board oscillator is disabled, or output the clock when it is enabled J1 EXCLK J2 OSC_EN J3 EXTRG External trigger signal input, 0V to 3.3V square wave, 10KHz to 40KHz only J4 Load JP Jumper for on-board RC load to MD2131DB1 high voltage output and XDCR connector J5 XDCR Jumper for on-board oscillator, short = disable, open = enabled MD2131DB1 waveform output, for SMA-cable to oscilloscope, high voltage! 0 to +/-350Vp-p max Power Supply Connector Power Supply Pin # Signal Name Description J7 - 1 VCC J7 - 2 GND J7 - 3 VDD J7 - 4 GND J7 - 5 VPP +3.3V, CPLD control logic supply voltage with current limit to 250mA Ground reference, 0V +5.0V MD2131 positive supply voltages with current limit to 50mA Ground reference, 0V +70 to100V, the high voltage supply with current limit to 30mA Voltage Supply Power-Up Sequence Step Signal Name Description 1 VDD +5.0, MD2131 positive supply voltages 2 VCC +3.3V, MOSFET gate biasing and CPLD control logic supply voltage 3 VPP +70V to 100V, the high voltage supply 4 EN Logic Active Enable logic control, active-high signal to MD2131 1 EN Logic Active Disable logic control, active-high signal to MD2131 2 VPP +70V to 100V, the high voltage supply, off 3 VDD +5.0V, MD2131 positive supply voltages with all input signals LOW, off 4 VCC +3.3, CPLD control logic supply voltage with EN = 0, off Power-Down Doc.# DSDB-MD2131DB1 A070114 11 Supertex inc. www.supertex.com MD2131DB1 MD2131DB1 Bill of Materials Reference Description Manufacturer’s Part Number Manufacturer C1 - C12 Capacitor, 0.1µF, 25V, ceramic, X7R, 0603 ECJ-1VB1E104K Panasonic C13, C14, C15 Capacitor, 0.027µF 50V ceramic, X7R 0603 ECJ-1VB1H273K Panasonic C18, C36 Capacitor, ceramic, 1.0µF 100V X7R 20% 1210 C3225X7R2A105M TDK C19 Capacitor, ceramic, 220pF 200V NP0 0805 ECJ-2YC2D221J Panasonic C32, C33, C34 Capacitor, 10µF 16V ELECT WT SMD UWT1C100MCL1GB Nichicon C5, C28 Capacitor, ceramic, 3300pF, 10%, 100V, X7R, 0603 06031C332KAT2A AVX D1, D4 LED: yellow, diff, 0805, SMD SML-LXT0805YW-TR Lumex D2 LED: red, diff, 0805, SMD SML-LXT0805IW-TR Lumex D3 LED: green, diff, 0805, SMD SML-LXT0805GW-TR Lumex D9 Diode Schottky, 100V, 1.0A, SMA B1100-13 Diodes Inc. D5 - D8 Diode Schottky, dual, 30V, SOT-363 BAT54DW-7 Diodes Inc. M1 Dual depletion 250V 3.0A N-MOSFET, 5x5mm, 8-Lead DFN package DN2625DK6-G Supertex Inc. R1 RES 1.00kΩ 1/16W 1% 0603 SMD ERJ-3EKF1001V Panasonic R2, R7, RES 49.9Ω 1/16W 1% 0603 SMD ERJ-3EKF49R9V Panasonic R3 - R6, R10, R14, R22 - R26 RES 200Ω 1/16W 1% 0603 SMD ERJ-3EKF2000V Panasonic R8, R15 RES 1.0Ω 1W 1% 2512 SMD ERJ-1TRQF1R0U Panasonic R9, R12 RES 100Ω 1W 1% 2512 SMD ERJ-1TNF1000U Panasonic R11, R27 PCB copper short NA NA R13 RES 1kΩ 1W 1% 2512 SMD ERJ-1TYF102U Panasonic R16 RES 49.9kΩ 1/16W 1% 0603 SMD ERJ-3EKF4992V Panasonic R17, R18, R19, R20, R21 RES 33.2kΩ 1/16W 1% 0603 SMD ERJ-3EKF3322V Panasonic R28 PCB copper short NA NA T1 LW = 22µH, 1:1:1 wideband ultrasound pulse transformer 750340727 Würth Electronics U1 IC ultrasound beamforming source driver 5x5mm 40-Lead QFN package MD2131K7-G Supertex Inc. U2, U3 IC CPLD, 72 MCELL, C-Temp, 44-VQFP XC9572XL-5VQ44C Xilinx U4 IC precision reference micropower ref, SOT-23 LM4040DEM3-2.5 National U5 IC voltage regulator, 1.5A, 2.5V, SOT-223 ADP3339AKC-2.5 ADI X1 Oscillator clock, 160.000MHZ, 3.3V, SMD JITO-2-DC3AE-160 FOX Electronics Supertex inc. does not recommend the use of its products in life support applications, and will not knowingly sell them for use in such applications unless it receives an adequate “product liability indemnification insurance agreement.” Supertex inc. does not assume responsibility for use of devices described, and limits its liability to the replacement of the devices determined defective due to workmanship. No responsibility is assumed for possible omissions and inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications refer to the Supertex inc. (website: http//www.supertex.com) Supertex inc. ©2014 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited. Doc.# DSDB-MD2131DB1 A070114 12 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: 408-222-8888 www.supertex.com