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ECE 477 Design Review Team 2 Fall 2011. Members: Bo Yuan, Yimin Xiao, Yang Yang , Jintao Zhang. Outline. Project overview Project-specific success criteria Block diagram Component selection rationale Packaging design Schematic and theory of operation PCB layout
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ECE 477 Design Review Team 2 Fall 2011 Members: Bo Yuan, Yimin Xiao, Yang Yang, Jintao Zhang
Outline • Project overview • Project-specific success criteria • Block diagram • Component selection rationale • Packaging design • Schematic and theory of operation • PCB layout • Software design/development status • Project completion timeline • Questions / discussion
Project Overview • The project we propose is a digital oscilloscope with playback function that provides almost any function of a typical oscilloscope, such as digital sampling, signal processing, scaling, cursor setting, reconstruction and visualization of signals. Additional features such as recording and replicating signals as a function generator, and write data to external storage (SD card).
Project-Specific Success Criteria • An ability to sample analog voltage signal range from -12 V to 12 V via BNC; • An ability to reconstruct and display the sampled signal on VGA display; • An ability to create user interface and realize basic signal measurements, such as frequency and peak-to-peak voltage; • An ability to store/load the sampled signal to/from external memory; • An ability to replay a stored signal.
Component Selection Rationale • Power Supply: • Using a standard 20 pin-Computer power supply unit. (Easy to use) • Use linear transistor 7805/7905/78M33 to provide low noise signal. Although 5V and 3.3V are available from the power supply, but along with a ripple voltage at 300mV. No significant current will be drawn from +/-5V line, large ripple voltage will be used in driving the analog MUX (+/-12V) and FPGA module (+5V), which has its own on board linear power supply system. • Using a 3V voltage reference for A/D conversion reference.
Component Selection Rationale • Analog circuit: • MAX14752: Analog MUX • Advantage: • Large tolerance (VSS-2 to VDD+2) compare to ADG1414 (VSS-0.3 to VDD+0.3). • Easy to control: Serial bus control, no SPI line require. • Got free sample from MAXIM, ADG1414 cost 8 dollar a piece. • Disadvantage: • High On-Resistance: 60 Ohm and ADG1414 is only 9.5 Ohm (Typ.). • More Pins to MCU: Each require four lines to controller, but ADG1414 is SPI shift register which can be implemented serially.
Component Selection Rationale • INA118: Instrumentation Amplifier • Advantage: low distortion, high tolerance (+/-40V), voltage shift up by Vref(1.5V). • LF411: Output driver op-amp: • Advantage: Low offset, low distortion, high power (capable to drive coaxial wires)
Component Selection Rationale • Digital Circuit: • MCU – STM32F407VG • Sampling rate 2.4 MHz maximum. • Relatively large RAM size (192 KB). • Crystal Clock: • 26MHz Crystal: Allowed maximum external clock. ARM Cortex-M4 will use an internal PLL to generate higher frequency clock up to 168MHz. Secondary clock (32.768KHz) is also laid out on board in case for need of precise clocking. • FPGA – Spartan 3E • VGA support. • Older version of the Spartan series, avoid voltage conversion.
