The Electronics Shop group can design, develop, construct, and test large quantities of various analog/digital instrumentation to stringent specifications. Nanovolts to kilovolts and millihertz to a gigahertz are the ranges covered. Over 300 pieces of quality commercial electronic test equipment ( mostly Hewlett Packard and Tektronix, some Wavetek, Keithley, and Fluke ) is available for loan to internal research groups. Commercial electronic test equipment is repaired inexpensively.
Chithra Kurup ---- Electronic Design Engineer
- Low noise design
- PC Board design (surface mount or thru-hole) using microwave techniques to yield low radiation and crosstalk
- Computerized PC Board layout using PCAD or PADS
- Comprehensive electronic CAD software is routinely used. ie. Analog/Digital mixed mode circuit simulator (SPICE) , System simulator, Data maniupulator/plotter, Symbolic and numerical math packages.
- Mechanical package (card cage etc.) design and assembly
- Use of Contract Manufacturers for large quantity assembly work. (Testing done internally)
- Novel circuit development
- Reliably triggering, age stable pulse width, 10 nsec recovery time, low cost, ECL One Shot
- Low noise, wideband, high voltage short circuit proof output, Piezzo driver composite op-amp amplifier
Sample of Completed Jobs
One year's activities
A busy fiscal year output was 1200 PC boards of seven types assembled and tested; a total of 8600 low noise wideband pulse processing/detection channels. Eleven card cages ( 5 types ) and 17 Power Supply Boxes (+/- 5V @ 350-750 watts DC out/box) designed, assembled, and tested. Power cables ( 50 amp capacity ) with connectors designed and assembled. Two hundred high speed (2-3 nsec risetime) photomultiplier tube bases were assembled and tested. PC board circuits developed by Electronic Shop in previous year(s). Four PC boards were laid out and three in the prior year. All electronics meet FNAL safety specifications. Semi-automatic test equipment was designed and developed with layout and construction of six ( two types ) chamber simulating wideband pulse distribution PC boards. Formal detailed test procedures were generated. Student labor was used extensively. The electronics comprise three jobs as follows.
- Wire/Drift Chamber Electronics - Four chambers used on KTEV experiment at FNAL
- Pre-amp Board ( 150 boards ): 16 channels/board, 90 MHz bandwidth ( risetime 4 nsec )/ channel, 670 na rms effective input noise, analog balanced outputs to drive 110 ohm twisted pair cables
- Amplifier and Discriminator Board ( 150 boards ): 16 channels/board, balanced inputs, discriminator threshold externally adjustable, discriminator outputs fed to ECL One Shots and subsequently to balanced line drivers that send out 55nsec pulses.
- KTEV Regenerator Electronics - used on KTEV experiment at FNAL
- Pre-amp Board ( 40 boards ): 5 channels/board, Photomultiplier tube low noise, wideband ( dc-150 MHz ) amplifier-limiter with complex dual pole-zero shaping, pulse trailing edge long tail compensation, and coaxial cable pre-compensation for 400 feet RG-58U.
- Amplifier Board (40 boards ): 5 channels/board, Wideband ( dc-200MHz ) amplifier. Boards with cable yielded pulses recovering within 1/2 % of peak amplitude within 20 nsec up to 100X overload
- Straw Chamber Electronics - Five chambers used on a Hadron Spectrometer Detector at CEBAF
- Termination Board ( 375 boards ): 16 channels/board, Impedance terminates and couples dc high voltage to straw. Recieves and distributes to straws, pulses used to test electronics.
- Readout Board ( 375 boards ): 16 channels/board, Amplifies and discriminates straw outputs, sending discriminator outputs to One Shots. For cost and instrumentation reduction, channel position information is encoded in One Shot pulse width ( suggested by Electronics Shop personnel ). Two independent groups of eight One Shots', each of the eight One Shots with a different closely controlled pulse width (+/- 1.5 nsec), outputs are logically OR'ed. Individually, both OR'ed signals are passed through individual balanced line drivers. The drivers outputs are attenuated prior to coupling to twisted pair cables to preclude excessive radiated feedback signals to straws which could cause non-linear oscillations. Pulse amplitude restoration board ( 50 boards ): Amplifies Readout Board outputs and retransmits balanced ECL format.
Designed and developed wire and straw chamber and KTEV regenerator electronics.
Modeled, developed, and/or built or manufactured analytical laboratory instruments electronics as follows:
- Scanning Tunneling Microscope ( STM ) Electronics - Assembled and wired two sets of electronics comprising seventeen PC boards. Designed, assembled, and wired main chassis, card cage, and electrometer pre-amp chassis. Redrew and clarified schematics. Designed, wired, and assembled cabling for a low noise grounding system. Modeled and simulated the STM non-linear feedback control loop in an attempt to improve performance. In collaboration with a graduate student a method for a noise cancellation technique was conceived and a patent disclosure was generated.
- Photo Absorption Chemical Detection Subsystem - A Photo-detector/electrometer with mounting assembly was designed, constructed, and tested
- Atomic Force Microscope Electronics - A pre-amp and differential amplifier was built and tested
- Auger/Esca Electron Energy Spectrum Analyzer Electronics - Designed and developed electronics comprising two rack size boxes containing power supplies and voltage dividers. Overall System Block Diagrams were generated to facilitate interconnecting complex grounding systems to achieve low noise.
- Modify a Perkin-Elmer ion gun controller to increase power capability
- Layout a diamond medium, particle detector PC board
Designed and/or developed:
- Computer controlled data acquisition system including software
- Multi-featured stand alone dual digital ramp generator
- Switchable wideband power buffer array consisting of 40 channels driving 5 volt 100 nsec risetime pulses into 50 ohm loads
- 500V @ 1a and a 500V @ 2a power supplies
- ECL pulse step delay/channel identifier/data compressor: 7 boards constructed, 64 channels/board in, 8 pulse data pairs out, balanced inputs and outputs
- High power pulse generator
- Intersite trigger using microwave link