High-speed interchip data transmission technology for superconducting multi-chip modules

We have developed an interchip data transmission scheme through passive tra nsmission lines on a multi-chip-module (MCM) carrier and 100-mum solder bum p bonds, In rapid single flux quantum (RSFQ) logic, digital data are in the form of single flux quantum (SFQ) pulses. A reliable scheme for transmissi on of SFQ pulses through non-superconducting solder bumps between chips thr ough a passive MCM substrate is yet to be established. Therefore, we have d evised a scheme that converts SFQ pulses into toggles in a voltage waveform for interchip transmission. Data in the form of SFQ pulses are reconstruct ed from this voltage waveform using a sensitive quantizing pulse receiver. Our objective is to eliminate the need for amplification of the transmitted signal, This is achieved by increasing the receiver sensitivity. However, a sensitive receiver, a de SQUID, may produce more than one SFQ pulse for e ach rising/falling edge of the voltage waveform. A simple circuit, pulse re surrection logic (PRL), is employed to discard any extra SFQ pulses. Togeth er with the sensitive quantizer, the PRL circuit makes our scheme error tol erant, We have demonstrated the receiver operation using 3-mum Nb RSFQ circ uits at frequencies up to 20 GHz.