TTI TG1000 10 MHz DDS Function Generator internals

[PChi]

In the spirit of 'Don't Turn It On Take It Apart' I lifted the lid of a TTi DDS Function Generator. It's quite nicely done apart from the plastic case.
The main Integrated Circuits are:-
Xilinx XC9572XL CPLD, 72 Macrocells.
NXP P80C32X2BBD 8051 Microcontroller, 256 Byte RAM.
AMIC A29040BL 512Kx 8 Bit Flash Memory.
M5M51008 128 K x 8 bit SRAM.
Analog Devices AD9834 75 MHz Complete DDS.
Analog Devices AD8055 300 MHz Operational Amplifier.
2 x Analog DevicesAD8056A Dual 300 MHz Operational Amplifier.
Analog Devices AD8561 Ultra fast 7 ns Comparator.
Analog Devices AD835A 250 MHz Multiplier.
Linear Technology LTC1257 12 bit Voltage Output DAC.
3 x Texas Instruments TL074 Quad Operational Amplifier.
2 x Texas Instruments TL072 Dual Operational Amplifier.
Texas Instruments 74HC4052 Dual 4-Channel Analog Multiplexor.
Texas Instruments 74HC4051 8-Channel Analog Multiplexor.
Texas Instruments 74HC4053Triple 2-Channel Analog Multiplexor.

[staze]

Any chance you have a higher res image? I'm really interested in those headers... the kind of look like serial connections. =)

[staze]

So, just picked up one of these myself. Attached are some higher res images. =)

I got the unit off eBay, and much like most other TTi equipment, it was pre-set for 230V, which just required removing the 0ohm resistor from Link2, and soldering in wires for Link1 and Link3 (see Voltage Links picture). Powered right up after that.

Of real interest is the header that seems to be for Serial (CORRECTION: This is JTAG). There's another header on the board (right below the transformer) that according to the service manual (which TTi happily provided, but it's for the TG2000) that seems to be for testing.

Also attached is a comparison of a 1khz 3Vpp square wave from the unit, and the calibration square wave built into the DS1052e. Obviously the TG1000 puts out a much cleaner square.

[majki]

I know this is very old thread, but maybe ...

If you still have it could you please take some high res photos about the output stage of this device?
I wonder what kind of output amplifier is used.

The device is capable 20Vpp open circuit, but none of the mentioned high speed op amps are capable to deliver it.

Maybe the LTC1257 is mistype and it is LT1227?

[staze]

Sure. Will try to take some when I get home.

[majki]

Thank you.
I am also curious about the aux out.
The fast comp is probably to generate TTL sync from the waveform, but the sweep marker which can be selected also as aux out is not TTL level. Do they use an analog switch to select from them?

[staze]

Didn't get to this last night, will try tonight.

Thanks.

[staze]

Hopefully these help.

[majki]

Thank you for your effort.

The output amplifier is visible on the second picture. The two small MSOP packages (IC18 and IC19) with hardly visible TI75 ADP marking code.

I guess they are Texas Instrument THS3001:
http://www.ti.com/lit/ds/symlink/ths3001.pdf
Page 29 shows the ADP package marking.

And because the output is 10Vpp to 50 Ohm load (means 20Vpp on the output of the opAms with 100 Ohm load)
the peak current is 100mA.
THS3001 can provide (in worst case) 85mA, so they use two of them in parallel.