Waveguides for capturing close-proximity electromagnetic radiation transmitted by wireless chips during testing on automated test equipment (ATE)
A test fixture has a flexible plastic cable that acts as a waveguide. The Device-Under-Test (DUT) is a small transceiver and antenna that operate in the Extremely High-Frequency (EHF) band of 30-300 GHz. The size of the DUT transceiver is very small, limiting the power of emitted electromagnetic radiation so that close-proximity communication is used. The envelope for reception may only extend for about a centimeter from the DUT transceiver, about the same size as the test socket. A slot is formed in the test socket very near to the antenna. The slot receives one end of the plastic waveguide. The slot extends into the envelope by the DUT transceiver so that close-proximity radiation is captured by the plastic waveguide. The waveguide has a high relative permittivity and reflective metalized walls so that the radiation may be carried to a receiver that is outside the envelope.
1. A test system for testing a Device-Under-Test (DUT) that emits close-proximity electromagnetic radiation, the test system comprising:
a test socket that holds the DUT during testing;
an interface board electrically connected between a test controller and electrical contacts of the DUT, when the DUT is held in the test socket;
an opening formed in the test socket, the opening extending into an envelope of electromagnetic radiation, the envelope created during testing by a DUT antenna included in the DUT;
a plastic waveguide having a first end inserted into the opening, the first end of the plastic waveguide being placed to receive electromagnetic radiation emitted by the DUT antenna during testing; and
a receiver antenna placed near a second end of the plastic waveguide, wherein the electromagnetic radiation emitted by the DUT antenna during testing is carried by the plastic waveguide to the second end and directed onto the receiver antenna, the second end disposed outside of the envelope.
2. The test system of claim 1 , wherein the envelope is less than 2 centimeters in its longest dimension;
wherein the DUT has a longest dimension that is less than 5 centimeters;
wherein the DUT antenna has a longest dimension that is less than 1 centimeter.
3. The test system of claim 1 , wherein the DUT operates in an Extremely High-Frequency (EHF) region of 30 GHz to 300 GHz;
wherein the electromagnetic radiation emitted from the DUT is EHF radiation having a frequency between 30 GHz and 300 GHz,
wherein the DUT is an EHF transmitter.
4. The test system of claim 3 , wherein the opening is a slot cut into the test socket, the slot sized to receive the plastic waveguide, and wherein the first end of the plastic waveguide is placed within the envelope.
5. The test system of claim 4 , wherein the DUT antenna radiates in an upward direction, wherein the envelope is above the DUT;
wherein the first end of the plastic waveguide is placed above the DUT antenna and facing the DUT to receive the electromagnetic radiation emitted by the DUT antenna during testing.
6. The test system of claim 4 , wherein the test socket further comprises:
a socket base connected to the interface board;
a DUT cavity in the socket base for receiving the DUT during testing;
a socket plunger situated above the socket base, the socket plunger pressing the DUT into the DUT cavity during testing;
wherein the opening is formed in the socket plunger, and when the DUT antenna radiates in an upward direction, the envelope extends into the socket plunger;
wherein the opening is formed in the socket base, and when the DUT antenna has radiates in a downward direction, the envelope extends into the socket base.
7. The test system of claim 6 , wherein the opening is formed horizontally in a side of the socket base, and when the DUT antenna radiates in a horizontal direction, the envelope extends into the side of the socket base.
8. The test system of claim 1 , further comprising:
a transceiver;
wherein the receiver antenna is in the transceiver;
wherein the plastic waveguide directs the electromagnetic radiation emitted by the DUT antenna into the receiver antenna in the transceiver;
wherein the test controller compares data received by the transceiver with a predetermined data pattern, the test controller indicating that the DUT is bad when the received data and the predetermined data pattern mismatch.
9. The test system of claim 8 , wherein the transceiver comprises a known-good transceiver being of a device type intended to be paired with the DUT in an end-user system.
10. The test system of claim 3 , wherein the DUT is a module containing an EHF transceiver integrated circuit (IC) and the DUT antenna.
11. The test system of claim 3 , wherein the DUT is an integrated circuit IC containing an EHF transceiver circuit that is integrated on a same semiconductor substrate with the DUT antenna.