PGA-625 fixture box with buses
PGA-625 fixture box (left) with 3 Chassis (right)

What are buses?

Buses are the pathways that create the connection between a drive resource and a pin in the switch matrix. The number of buses allows multiple drive types and settings to be available to the switch matrix and the DUT.

In electrical terminology, a bus is a conductor in which signals travel both ways. In curve tracing, we source and sense the signal through the buses. Bus configurations determine the applications of the curve tracer. However, your device’s pin count will determine the curve trace model.

 

Pin Counts 

Our automatic curve tracers come in a range of configurations scaled to meet your needs. They scale in two directions; pin count and the number of buses.

To make your decision, most users only need to answer a couple of questions:

    1. What is the largest device you plan to test in your lab?
    2. Do you want to be able to power up the device to measure IDD or curves in the powered state?
      • If so, how many voltages will your device need to power up?

The pin count you need ultimately determines the curve tracer. See below for common configurations.

For the MT Century, 100 pins are the standard pin count. The MT Century uses a cable set with a 100-pin connector which is compatible with many low pin DUT boards. We developed the 950 series fixture with Mini and Extended Mini cards as the primary fixture for the MT Century. Dedicated R1 or R4 DUT boards can replace the 950 series but limits test abilities to your specified applications.

950 series benchtop test fixture for curve tracing and curve tracers
950 Series
R1 DUT board for curve tracer
R1 DUT Board
R4 DUT Board for curve tracing
R4 DUT Board with R1 back

The MultiTrace has a flexible and wide range of pin counts:

216 pins are the lowest pin count on the MultiTrace which uses a PGA-625 fixture box with integrated drive bus connections and jumper matrix.

324 pins are available only on the MultiTrace. When configured as a 324-pin curve tracer, the PGA-625 fixture is an 18x18 array.

432 pins are available on the MultiTrace.  When configured on the PGA-625 fixture box, the pins form a 21x21 array with 9 pins depopulated from the lower right. These pins are easily remapped on the built-in jumper matrix for a larger pin count.

625 pins are the largest pin count for the MultiTrace. The PGA-625 fixture box is configured to the full 25x25 array. 625 pins are also available on the MegaTrace if you are expecting to expand the pin count later.

The MegaTrace supports larger pin counts:

MegaTrace Octopogo Interface with Test Socket + Adjustable Lid
1,080 pins are available on the MegaTrace with two options of interfaces: the Octopogo™ or the Large Format Breakout Board. The MegaTrace is commonly configured with the Octopogo™. With the Octopogo™, you cannot expand larger than 1152-pin count. You will need the Large Format Breakout Board for further expansion or larger pin counts.

Universal breakout board for curve tracing
MegaTrace Large Format Breakout Board for 2160 Pin Count

2,160 pins are available only on the MegaTrace with the Large Format Breakout Board. This configuration is the largest curve tracer RTI has to offer.

Bus Configurations

Our curve tracers share the same internal architecture and are available with 2, 4 or 6 bus configurations across the full range of pin count available. Within a curve tracer, each pair of buses is integrated with a common set of drives. Increasing the number of drives will increase the number of buses.

2 buses are paired with 4 SMU supplies we call drives. Two precision drives are connected to the switch matrix input and your device is connected to the output.  Pins can be grounded, or curve traced. The primary application for this configuration is Unpowered Curve Tracing, but other custom setups are possible. Contact us to discuss customization.

4 buses are paired with 8 SMU supplies we call drives. This allows connection of power and ground, plus one logic level and a power source. This setup is capable of powered curve tracing, IDD measurements as well as unpowered curve tracing, but is limited to a single VDD voltage.

6 buses are paired with 8 SMU supplies we call drives. This allows connection of power and ground, plus one logic level and a power source. This setup is capable of powered curve tracing, IDD measurements as well as unpowered curve tracing, but is limited to two or four VDD voltages.

Below is a diagram of the 2 Bus configuration with connections to pins, cards, and fixture box.

2 Bus Diagram

Curve Tracer Configurations

MT Century: A compact benchtop curve tracer that supports 96, 100 or 108 pins depending on the fixture connected to it. 

    • The MT-Century is a fully automated version of our manual switch boxes and is compatible with the same fixtures. Users of switch boxes often upgrade to the MT Century.
    • The MT Century is a benchtop instrument and consists of a single AT sized chassis along with a drive bus breakout box and compact fixture such as the 950 series.

MultiTrace: The original curve tracer and supports 216, 324, 432, and 625 pins depending on the array setup. Other pin counts are available within the 216-625 pin range. Contact us to discuss customization.

    • Consists of a PGA-625 fixture box with a ZIF socket in a 25x25 pin configuration.
    • The MultiTrace is a benchtop instrument and is typically one to three AT sized chassis along with the PGA-625 fixture box and associated cables. The DUT board is plugged into the ZIF socket for testing.

MegaTrace: Our largest curve tracer capable of supporting 625 to 2,160 pins. 1,080 pins are the most common size. Other pin counts are available within the 625-2160 pin range. Contact us to discuss customization.

    • The MegaTrace has two options of interfaces: the Octopogo™ interface or the Large Format Breakout Board. The MegaTrace is commonly configured with the Octopogo™. With the Octopogo™, you cannot expand larger than 1152-pin count. You will need the Large Format Breakout Board for further expansion or for larger pin counts.
    • The MegaTrace is a cart-sized instrument and is self-contained including the PC controller. The DUT board plugged into the top of the curve tracer’s interface.
    • Remote cable fixtures are available for Fault Isolation

What are drives?

Drives are what we call the power supplies that do all the work.

All drives in our curve tracers are 4 quadrant Source Measure Units (SMU), meaning they can source or measure positive and negative voltages and currents.

The drives have multiple operating modes that allow use as a current source, voltage source or curve tracer source, and are programmable to the full resolution of 16-bit A/D and D/A channels.

Most drives have a range of +/-15V and +/-1A. But some drives have a range of +/-100V and +/-100mA.

Current measurement accuracy depends on settings, especially the series resistor selection. Measurements as low as 1nA are possible on most drives.

Whether a drive is connected to a switch matrix input or not depends on the bus configuration:

    • 2 bus configurations have 4 SMU Drives
    • 4 and 6 bus configurations have 8 SMU Drives (chart of specs below)

 

Drive Type Spec Ranges 2 bus 4 bus 6 bus
Precision drive +/-15V and +/-1A 8 series resistors 2 1 1
Power Drive +/-15V and +/-1A 1 series resistor 1 2 2
High Voltage drive +/-100V and +/-100mA. 5 series resistors 1 2 2

Contact us for detailed technical specs.