Design and performance of the Elefant Digitizer IC for the BaBar Drift Chamber

A 250,000 transistor full custom integrated circuit for the readout of drift chamber signals has been developed, produced and characterized. The `Elefant' (ELEctronics For Amplitude 'N Timing) Digitizer IC is designed to measure both the charge and the single electron time of arrival of sense wire signals from the BaBar drift chamber. By combining a FADC (Flash Analog-to-Digital Converter) and a TDC (Time-to-Digital Converter) for each channel, the digitizer IC can be optimized and simplified, to achieve the physics goals required of the drift chamber while reducing the per channel costs of the electronics. The Elefant IC also implements portions of the BaBar Trigger protocols to simplify the connection of the chip to the rest of the BaBar detector. Each IC contains eight complete independent channels. The circuit has been implemented in a 0.8 μm triple metal CMOS process and fabricated in production quantity to fully instrument the BaBar Drift Chamber and are now in operation. Performance results of the IC will be presented.