1. ATE Contact Test thru’ Analog Switch

2. Conventional ATE Contact Test
CASE#1
CASE#2
DUT pin is only connected to the ATE on the loadboard
Force current -200ua on the DUT pin
Measure voltage on the DUT pin
DUT pin needs to be connected to the ATE and Support IC as well for other functional testing
Use a mechanical relay to switch between ATE and Support IC
Force current -200ua on the DUT pin
Measure voltage on the DUT pin
ATE_CH-xxx
Rly
Support IC
ATE_CH-xxx
DUT
DUT

3. Relays Advantages Issues Low contact resistance – ~<0.5 ohms
ATEs can easily control them
Higher bandwidth
Issues
Bulky
Expensive
Mounting it and reworking it on the board when surface mounted
Takes real estate on the board

4. Analog Switches Alternate solution to relays are analog switches Pros
Small footprint, one IC can switch many DUT pin
Easy manufacturability and rework
Low cost
High Bandwidth
Issues
Higher ‘ON’ resistance
Pose problem in doing ATE contact test due to their own clamp diodes
Need extra ATE supplies to power them

5. Analog Switches – No Issues
Higher ‘ON’ resistance
With good selection of a switch, this can be tolerated
Need extra ATE supplies to power them
Modern ATEs have many power supplies to power the analog switch
Pose problem in doing ATE contact test due to their own clamp diodes
This can be alleviated by skewing the power supplies of the switch

6. Regular Functional Test
Supporting IC
Regular VDD/VSS
3.3v
Aout-B
DUT
Aout-A
Ain
ATE_CH-xxx
With the analog switch supplies at 3.3v/0.0v, the switch’s Ain pins will connect to either Aout-A or Aout-B and both the clamp diodes on the switch’s pins will act as clamps during functional testing of the DUT thru the ATE or Receiver IC
SEL 0v
Regular IO control voltage for Mux control Vil = 0v Vih=3.3v

7. Contact Test Supporting IC Skewed VDD/VSS DUT
Aout-B
DUT
Aout-A
Ain
ATE_CH-xxx
SEL
With the analog switch supplies at 1.3v/-2.0v, the switch’s Ain pin will be connected to Aout-A and both the clamp diodes of the switch’s pins will be reverse biased during contact test of the DUT pins thru the ATE
-2v
Skewed IO control voltage for Mux control Vil = -2v Vih=1.3v