FED 9U Analog Characterization

1. FED 9U Analog Characterization Stefanos Dris CERN & Imperial College

2. Motivation • Analog performance of the FED front end electronics. • Match on-FED performance with lab measurements of bare ARx12 modules. • Check functionality of ARx12 matching capacitor switch settings-i.e., do the FED’s front end analog electronics affect what capacitance setting should be used on the ARx12s? Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions

3. Test Setup • For electrical probing measurements, pulse generator set to trigger automatically and continuously. • For pulse reconstruction on the FED, TSC provides synchronous triggers to both the pulse generator and the FED. • FED clock skewed (0-31) in order to reconstruct the incoming pulses. Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions

4. Trigger Setup Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions • Triggers to FED and pulse generator synchronized. • Pulse generator set to output a pulse 2μs after receipt of trigger. • FED capture length = 7μs, hence pulse appears approximately in the middle of capture.

5. FED Front End Analog Electronics Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions • Probing at: • 100Ohm ARx12 output resistor • Differential driver output • Differential input to ADC

6. AOH Input and Output Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions • Input pulses to AOH: • 800mV differential • 1.25V common mode

7. ARx12 Output Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions • Receiver output is similar to what we see in production testing.

8. ARx12 Batch R4 Settling times for all channels of the 10 production test modules of batch R4 NGK supplied bandwidths for all channels of all 420 modules of batch R4 Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions • Receivers mounted on the FED used for these tests comes from ARx12 batch R4. • From lot acceptance testing, and NGK bandwidth data, R4 modules perform best @1000fF. • A few of the first modules of the batch have much lower bandwidths, but these were used for other purposes (mounted on OFEDs).

9. Differential Driver Output Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions • Settles better at 800fF, as opposed to 1000fF. Overshoot in step response of the differential driver IC? • Rise time only slightly worse than ARx12 output pulses.

10. Differential Driver Output Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions • Settles better at 800fF, as opposed to 1000fF. Overshoot in step response of the differential driver IC? • Rise time only slightly worse than ARx12 output pulses.

11. TrimDAC Operation Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions

12. ADC Input Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions • Differential input to ADC almost impossible to probe properly. • Strange offsets seen between measurements on the same C setting, as well as slight changes in amplitude.

13. FED Reconstructed Pulses Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions • Best capacitance setting is 800fF. • Thus, for an ARx12 module showing 1000fF best capacitance setting in the tracker opto lab, the effect of the FED’s front end electronics is to change this best setting to 800fF. • Rise time is a lot worse than in previous stages (~2ns more than at ARx12 output).

14. Linearity • Two non-inverting outputs of the pulse generator used. • Period set to 500ns, 1% duty cycle. • FED set to acquire 280 points, 25ns apart. • Pulse Generator controlled by LabView VI, changes each output’s level to obtain required resultant value. • Level change and FED acquisition done manually, 31 steps from -0.5V to 0.71V. • Measurement took less than a minute. Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions

15. Linearity Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions • Linearity better than 1% for an input range of more than 800mV was achieved, despite the dodgy method. • With a more precise method, the linearity should be at least as good as the result shown here.

16. Conclusions • Best C-setting should be selected taking into account the FED front end analog electronics (up to ADC), not just the optical link components. In this case, the receiver should be set to 800fF, not 1000fF as the production tests would suggest. • More FED channels need to be tested in this manner to see if the ‘change’ in best C-setting is a constant effect. That is, should all ARx12s with best C-setting of 1000fF in the production tests be set to 800fF when mounted on FEDs? • What is the effect of selecting the wrong capacitance setting on the performance of the Tracker? In the last beam test, we wanted to check this by constructing Landau curves for all different capacitance settings, as well as for different sampling points. Motivation Test Setup FED front end electronics Results Linearity test setup Linearity Results Conclusions

17. Impossible is Nothing