Difference between revisions of "Bias Card RevD to RevE changes"

From MCEWiki
Line 6: Line 6:
 
: Vah or 10V supply is not used by Rev. F cards anymore. The reference voltage for the DACs is generated from pVa or 6.2V supply instead.
 
: Vah or 10V supply is not used by Rev. F cards anymore. The reference voltage for the DACs is generated from pVa or 6.2V supply instead.
 
: Vah is used in Rev. D cards to provide the reference voltage for the DACs.
 
: Vah is used in Rev. D cards to provide the reference voltage for the DACs.
 
; Faster Bias lines
 
:In order to allow fast switching of the 32 regular biases (<1MHz), the output opamp (U10) is replaced with a faster opamp and the 10kHz output filter is removed (compared to Rev. D). This allows Rev. F cards to be used for switching SQ2FB lines at row-visit rate.
 
  
 
; Software considerations
 
; Software considerations

Revision as of 11:34, 22 October 2012

Low-noise Bias lines
Low noise bias lines are meant to be used as TES bias lines. Bias Card Rev. E provides 12 independent bipolar low-noise bias lines (LN_BIAS) in addition to the 32 regular biases. The 12th low-noise bias is what was called det_bias in Rev. D cards. Rev. D cards shared a DAC between two outputs called Heater and det_bias.
Note that the low-noise bias line in Rev. D was unipolar with 0 to +5V range, while low-noise bias lines in Rev. F are bipolar from -5V to +5V. At powerup, the output voltage is 0V, equivalent to an input pattern of 0x8000.
10V supply
Vah or 10V supply is not used by Rev. F cards anymore. The reference voltage for the DACs is generated from pVa or 6.2V supply instead.
Vah is used in Rev. D cards to provide the reference voltage for the DACs.
Software considerations
To make the 12 bias lines commandable, set $hw_rev["bc"] = "revE" (or greater) in mce.cin . This will add a op_xor entry in mce.cfg file to make a 2's complement interpretation of values entered so that wb bc2 bias 0 is aligned with 0V and wb bc2 bias 32767 with +5V.
in experiment.cfg, set hardware_fast_sq2 accordingly
Firmware consideration
The FPGA pins assigned to control lines for ln_bias DACs are not compatible with Rev. D nor Rev. F cards. Therefore, special RevE firmware is needed to be able to excercise ln_bias DACs (bias command).