IBM CLC-CAPT-PCASM manual Operation of Data Capture Board

			BPF
		FILTERED
		SIGNAL
		SOURCE
					OPTIONAL
					CLOCK SOURCE
+5V
VCC	VCC		Clock	Ain	CLK
(2A)						10-16dBm
					Optional
	GND	Data
			Data		TTL
		Capture			Oscillator
		Board		ADC
	Serial I/O		Power	Evaluation
				Board

64P I/O

CONNECTOR

To PC Serial

COMM PORT #1 or #2

Hardware

1.CLC3790093 Data Capture Board (CLC-CAPT-PCASM)

2.CLC Evaluation Board. Several ADC products can be evaluated with this system. Currently, the choices are the CLC5956 (12-bit 65MSPS ADC), or the CLC5958 (14-bit 52MSPS ADC). Each product has a unique evaluation board (CLC5956PCASM or CLC5958PCASM) which plugs into the data capture board.

3.Personal Computer. An IBM-Compatible PC running Windows® 95, Windows® 98, or Windows® NT. The PC should have an available serial port capable of operating at 115,200 baud. These ports are usually labeled and referred to as COM1 and COM2. The captured data is stored in a file on the PC to allow custom analysis.

4.Serial Cable. A standard serial interface cable is provided. This cable connects the data capture board to the PC.

5.Power Supply. The data capture board requires a single +5V supply. This power is applied at connector J3. A 2-amp supply will provide enough current for the evaluation board and the data cap- ture board. Note that the power for the evaluation board is provided from the data capture board through the 64-pin connector J1.

6.Input signal. You can provide any type of input signal that you feel is appropriate to your system testing. The data analysis software provided with the data capture board is oriented toward analysis of single tone sinewave inputs. Our recommendation for high purity, low phase noise reference signal sources is the Hewlett Packard HP8644B synthe- sizer. It provides an excellent input stimulus for evaluating ADC performance.

7.Bandpass or lowpass filter. Even with a good sinewave source, you will need to filter out the har- monics of the signal source. A bandpass filter also enables filtering of the wideband noise of the refer- ence source. As an example, Allen Avionics (Mineola, NY) passive filters are used for most of our converter testing.

8.Clock Source. If you wish to test the ADC with a fixed clock frequency, you may install a standard TTL oscillator in the socket provided on the evaluation board. Otherwise, you will need to provide a low phase noise sinewave or square wave clock source at the appropriate SMA connector on the evaluation board. An amplitude of 10 to 16dBm is recommended. Here, again, the HP 8644B is a good choice.

Software

1.National Semiconductor Software. All of the required software is provided on a CD-ROM. To install the software now, insert the CD-ROM into your computer and follow the directions. The default installation copies all of the files to a directory called “c:\nsc”. The data capture software is called “capture.exe”.

2.Matlab. A copy of Matlab version 5.1 or later is required to operate the analysis routines. If you sim- ply wish to capture data to a file on your PC and pro- cess the data with your own analysis software, then you will not need Matlab. For more information about Matlab, please see their website at http:// www.mathworks.com.

3.Matlab script files. The Matlab script files for data analysis are located in the “c:\nsc\mfiles” directory. These script files are run from the Matlab command prompt.

Documentation

The CD-ROM includes all of the following documentation, with the most current versions available on our website at http:// www.national.com:

1.CLC5956 data sheet

2.CLC5958 data sheet

3.Data Capture Board User’s guide (this document).

Additional information is included on other products and their evaluation boards. If you are evaluating the Diversity Receiver Chip Set, please refer to Section III of this manual.

Operation of Data Capture Board

When evaluating the performance of an ADC, the data capture board has two main modes of operation. In the first mode, data is captured from the evaluation board under test at the full sample rate of the ADC. A contigu- ous set of 32k data samples is captured into a FIFO memory on the board, and then this data is moved over to the PC at a slower rate. The data set is stored in a file on the hard drive for later analysis. The data is stored in an ASCII file in exactly the format that it is output from the converter. For the CLC5956, the two’s complement 12-Bit data is stored as numbers ranging from 0 to 4095. In the case of the 14-bit ADC5958, the two’s complement data ranges from 0 to 16383. Each value is terminated with a carriage return, hexadecimal 0D. Note that the two’s

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