Getting faster bandwidth HervéGrabas Getting faster bandwidth - Hervé Grabas 1
Present bandwith status Limiting factors: Cables Board Bonding wires Input line Sampling capacitance and switch Getting faster bandwidth - Hervé Grabas 2
Cable status Plot of the 3dB cutoff frequency of cable function of length Safe to use cables under 30cm of length Getting faster bandwidth - Hervé Grabas 3
Board status On board measurment with 3Ghz network analyser 2Ghz bandwidth measured with network analyzer Getting faster bandwidth - Hervé Grabas 4
Board + Chip status On board measurment with 3Ghz network analyser 500Mhz bandwidth measured with network analyzer Getting faster bandwidth - Hervé Grabas 5
Board bandwith limitation! Decoupling cap shown here are on the board! Within the actual Psec3 tester board: Getting faster bandwidth - Hervé Grabas 6
Board bandwith limitation! Decoupling cap shown here are on the board! Within the actual Psec3 tester board: Getting faster bandwidth - Hervé Grabas 7
Board bandwith limitation! Decoupling cap shown here are on the board! Within the actual Psec3 tester board: Getting faster bandwidth - Hervé Grabas 8
Board bandwith limitation! Decoupling cap shown here are on the board! Within the actual Psec3 tester board: Getting faster bandwidth - Hervé Grabas 9
Board bandwith limitation! Decoupling cap shown here are on the board! Within the actual Psec3 tester board: 2. The signal returns via gnd on the board through all decoupling cap of all channels and the DAC. Getting faster bandwidth - Hervé Grabas 10
Board bandwith limitation! Decoupling cap shown here are on the board! Within the actual Psec3 tester board: 2. The signal returns via gnd on the board through all decoupling cap of all channels and the DAC. 3. The signal returns through the line to the connector Getting faster bandwidth - Hervé Grabas 11
Board bandwidth fix Future Psec3 tester board: Getting faster bandwidth - Hervé Grabas 12
Board bandwidth fix Future Psec3 tester board: Getting faster bandwidth - Hervé Grabas 13
Board bandwidth fix Future Psec3 tester board: 2. The DAC is RF shielded by an inductance Getting faster bandwidth - Hervé Grabas 14
Board bandwidth fix Future Psec3 tester board: 2. The DAC is RF shielded by an inductance 3. The signal returns via the per-channel dedicated return line (no ground) Getting faster bandwidth - Hervé Grabas 15
Chip on board bandwidth issue Psec3 tester board with chip: Getting faster bandwidth - Hervé Grabas 16
Chip on board bandwidth issue Psec3 tester board with chip: Getting faster bandwidth - Hervé Grabas 17
Chip on board bandwidth issue Psec3 tester board with chip: 2. Due to parasitic capacitive ground coupling in the chip the RF signals illuminate the whole chip Getting faster bandwidth - Hervé Grabas 18
Chip on board bandwidth issue Psec3 tester board with chip: 2. Due to parasitic capacitive ground coupling in the chip the RF signals illuminate the whole chip Getting faster bandwidth - Hervé Grabas 19
Chip on board bandwidth issue Psec3 tester board with chip: 2. Due to parasitic capacitive ground coupling in the chip the RF signals illuminate the whole chip 3. The signal returns via the less inductive ground pads to the connector. Getting faster bandwidth - Hervé Grabas 20
Chip on board bandwidth issue Psec3 tester board with chip: 2. Due to parasitic capacitive ground coupling in the chip the RF signals illuminate the whole chip 3. The signal returns via the less inductive ground pads to the connector. Getting faster bandwidth - Hervé Grabas 21
Chip on board fix Psec3 tester board with chip fixed: Getting faster bandwidth - Hervé Grabas 22
Chip on board fix Psec3 tester board with chip fixed: Getting faster bandwidth - Hervé Grabas 23
Chip on board fix Psec3 tester board with chip fixed: 2. Losses are minimized by having a single specific return path Getting faster bandwidth - Hervé Grabas 24
Package bandwidth & fix With and without bonding wires Getting faster bandwidth - Hervé Grabas 25
Other bandwidth/losses issues? Input line Return line Line dimension:.8µm 3072µm Line resistance: 146 ohms Getting faster bandwidth - Hervé Grabas 26
Where are we limited in bandwidth summary Factors Description Quantization Fix The measurement in itself (cables) The board The bonding wires of package The input line of the chip Total cable size <30 Small cables, loss substraction and calibration Return path grounded 2Ghz Bandpass filter Cutoff freq ~ 1Ghz Flip chip Parasitic capacitance and resistance C ~ 1.5pF R~ 150Ohms Dedicated return path Higher metal level Getting faster bandwidth - Hervé Grabas 27