Compression and decompression of stimulus and response waveforms in automated test systems

Abstract

An automated test system for a device under test (DUT) compresses the stimulus waveform before transferring it to a storage device or over a data transfer interface. The compressed stimulus waveform data are decompressed, and if required converted to analog form, then applied as a stimulus to the DUT. In response, the DUT produces a response waveform. The response waveform is compressed before transferring it to a storage device or over a data transfer interface. If the response waveform is analog, it is converted to digital before compression. The compressed waveform is decompressed for further analysis or display by a host computer. Features of the response waveform can be calculated from the compressed or uncompressed waveform data. Several configurations that include compression and decompression of stimulus and/or response waveforms in test systems are described.

1 . In a test system for a device under test (DUT) that includes a host processor, the host processor providing a stimulus waveform to a stimulus interface coupling the host processor to an input of the DUT, a device output interface connected to an output of the DUT and a response interface coupling the host processor to the device output interface, a method for sending a response waveform to the host processor from the DUT, wherein the response waveform is generated by the DUT in response to the stimulus waveform, the method comprising:
 receiving the stimulus waveform at the input of the DUT from the stimulus interface;   at the device output interface:
 receiving the response waveform from the output of the DUT;
 compressing a plurality of samples of the response waveform to form compressed response waveform data; 
 transferring the compressed response waveform data to the response interface; 
 
   at the host processor:
 retrieving the compressed response waveform data from the response interface; and 
 decompressing the compressed response waveform data to form a decompressed response waveform. 
   
   
   
       2 . The method of  claim 1 , wherein the response waveform is an analog response waveform, the step of receiving the response waveform further comprising:
 converting the analog response waveform to a digital form to produce the plurality of samples of the response waveform.   
   
   
       3 . The method of  claim 1 , wherein at least one of the step of compressing and the step of decompressing is performed in accordance with a control parameter. 
   
   
       4 . The method of  claim 1 , wherein the step of compressing operates in one or more compression modes, including at least one of a lossless compression mode and a lossy compression mode. 
   
   
       5 . The method of  claim 1 , wherein the response interface comprises a data storage device, including but not limited to at least one of a memory and a computer-readable medium, the step of transferring further comprising storing the compressed response waveform data in the data storage device and the step of retrieving further comprising retrieving the compressed response waveform data from the data storage device. 
   
   
       6 . The method of  claim 1 , wherein the response interface comprises a data transfer interface, including but not limited to at least one of a bus, a cable and a network, the step of transferring further comprising transferring the compressed response waveform data via the data transfer interface and the step of retrieving further comprising receiving the compressed response waveform data from the data transfer interface. 
   
   
       7 . The method of  claim 1 , further comprising:
 measuring a feature of at least one of the response waveform, the compressed response waveform data and the decompressed response waveform.   
   
   
       8 . The method of  claim 1 , wherein the stimulus waveform is an analog stimulus waveform, the host processor providing a plurality of stimulus waveform samples to the stimulus interface, the method further comprising:
 converting the stimulus waveform samples to the analog stimulus waveform, wherein the analog stimulus waveform is provided to the input for the step of receiving.   
   
   
       9 . In a test system for a device under test (DUT), an apparatus for transferring a response waveform from the DUT to a host processor in the test system, the DUT having an input and an output, wherein the DUT responds to a stimulus waveform received at the input to produce the response waveform at the output, wherein the stimulus waveform is provided by the host processor, comprising:
 a stimulus interface coupled to the host processor and the input of the DUT to provide the stimulus waveform to the DUT;   a device output interface coupled to receive the response waveform from the output of the DUT;   a response compressor coupled to the device output interface and compressing a plurality of samples of the response waveform to form compressed response waveform data;   a response interface coupled to receive the compressed response waveform data from the response compressor; and   a response decompressor coupled to receive the compressed response waveform data from the response interface and decompressing the compressed response waveform data to form a decompressed response waveform provided to the host processor.   
   
   
       10 . The apparatus of  claim 9 , wherein the response waveform is an analog response waveform, the device output interface further comprising:
 an analog-to-digital converter coupled to receive the analog response waveform from the output of the DUT and converting the analog response waveform to a digital form to produce the plurality of samples of the response waveform.   
   
   
       11 . The apparatus of  claim 9 , wherein at least one of the response compressor and the response decompressor operates in accordance with a control parameter. 
   
   
       12 . The apparatus of  claim 9 , wherein the response compressor operates in one or more compression modes, including at least one of a lossless compression mode and a lossy compression mode. 
   
   
       13 . The apparatus of  claim 9 , wherein the response interface comprises a data storage device, including but not limited to at least one of a memory and a computer-readable medium. 
   
   
       14 . The apparatus of  claim 9 , wherein the response interface comprises a data transfer interface, including but not limited to at least one of a bus, a cable and a network. 
   
   
       15 . The apparatus of  claim 9 , wherein the device under test, the device output interface and the response compressor are adapted to be implemented in a self-testing system for the device under test, wherein the self-testing system is coupled to provide the compressed response waveform data to the response interface. 
   
   
       16 . The apparatus of  claim 10 , wherein the device under test, the device output interface, including the analog-to-digital converter, and the response compressor are adapted to be implemented in a self-testing system for the device under test, wherein the self-testing system is coupled to provide the compressed response waveform data to the response interface. 
   
   
       17 . The apparatus of  claim 9 , wherein the stimulus waveform is an analog stimulus waveform, the host processor providing a plurality of stimulus waveform samples to the stimulus interface, the stimulus interface further comprising:
 a digital-to-analog converter to convert the stimulus waveform samples to the analog stimulus waveform provided to the input of the DUT.