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AB-PO-HP/gf 31.8.2007
Setup of the 22-bit Delta-Sigma converter, v. 10.1
Objective
The Delta-Sigma 22 bits, a third order modulator originally developed by John
Pett, needs a few starting up adjustments, ageing and setup. It is only carried out once and
the procedure is fully explained here. Further adjustments should not be necessary, but
are replaced by a digital calibration explained elsewhere
Tools required
This procedure requires a 10 Volts reference (Metron PBC), an oscilloscope, a
DVM (8.5 digits type HP 3458), a frequency/counter device, a soldering iron (SMD) and
a set of precision resistors (E24 / 1206, SMD) from 1 to 30 Ohms. Normal lab tools will
help, like screwdrivers and a pot-trimmer. A PC with SLAP running an FGC is
necessary for the evaluation of the 500 kHz/1 MHz output data stream.
Description of the subsystems
There are two PCBs inside the module, the power supply card and the modulator
card. The power supply provides +/-15V for the analog part, +5V for the digital control
and +/-4Vfor the Peltier element. The