Liverpool BeO Forward Hybrid with 12 x ABCDs

Preliminary Results

A Liverpool BeO Forward Hybrid has been populated with 6 x ABCD-N to both sides (12 x ABCDs in total to be readout).
The hybrid and ABCDs addressing format is as follows:

Geographical address is for an Even module.
ABCD geographical addressing is (Top side): M0, S1, S2, S3, S4, S5 (Bottom side): S8, S9, S10, S11, S12, E13

All results presented are with Edge Detect enabled and using Edge Data Compression.
40MHz clock mark-space ratio set to 1:1.
Nominal values of VCC = 3.5V and VDD = 4.0V (measured on hybrid).

Initial results have been obtained with the front-end bias set for the low and high current biasing.
Threshold was scanned from 0mV - 625mV in 2.5mV steps, injected charge was from 1fC to 4fC in steps of 0.5fC.
The results shown are for injected charges of 2fC, 3fC and 4fC in Postscript format.

Results
Low current operating region
Injected Charge (fC) Noise (fC) Gain (mV/fC) Threshold (mV)

2 Noisel2.ps Gainl2.ps Thresl2.ps

3 Noisel3.ps Gainl3.ps Thresl3.ps

4 Noisel4.ps Gainl4.ps Thresl4.ps

**High current operating region**
Injected Charge (fC)	Noise (fC)	Gain (mV/fC)	Threshold (mV)
2	Noiseh2.ps	Gainh2.ps	Thresh2.ps
3	Noiseh3.ps	Gainh3.ps	Thresh3.ps
4	Noiseh4.ps	Gainh4.ps	Thresh4.ps

**Chip Parameters (Low current operating region)**
Parameter	M0	S1	S2	S3	S4	S5	S8	S9	S10	S11	S12	E13
Front-end bias (uA)	73.6	73.6	64.4	73.6	73.6	73.6	64.4	73.6	73.6	73.6	73.6	73.6
Front-end shaper (uA)	18	18	18	18	18	18	18	18	16	16	14	14
Strobe delay (bits)	23	23	23	23	23	23	23	23	23	23	23	23

**Chip Parameters (High current operating region)**
Parameter	M0	S1	S2	S3	S4	S5	S8	S9	S10	S11	S12	E13
Front-end bias (uA)	220.8	211.6	202.4	211.6	211.6	211.6	193.2	211.6	211.6	211.6	211.6	211.6
Front-end shaper (uA)	18	16.8	18	21.6	18	16.8	16.8	18	19.2	16.8	16.8	19.2
Strobe delay (bits)	27	27	27	25	27	27	27	27	27	27	29	27

Summary

The Digital stages on all 12 ABCDs are functioning ok.
The Analogue stage still has a very narrow range for the front-end bias (for either high or low current operating regions).
Noise, Gain and Threshold compare well with the results obtained for the single-sided hybrid.
Noise performance is better when operating in the low current region, < 600 ENC compared to > 625 ENC for high current region.
Improved gain response and reduced spread in the low current region, compare gain of 70mV/fC to 60mV/fC.
Threshold response is 'flat' for nominal injected charges in the low current region.

When operating in the high current region there is increased sensitivity to the chips bias settings, as more chips are turned 'on' this can modify the bias settings of those chips already biased. It thus becomes an iterative process of checking chip performance as more chips are turned 'on' and then maybe having to modify the bias settings on those chips which had already been configured with optimum bias settings.

The Forward Hybrid with 12 x ABCDs has been readout successfully with no obvious degradation in performance when compared to results obtained with a Hybrid with 6 x ABCDs.

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Last modified: 29/10/98