InP-HBT optoelectronic integrated circuits for photonic analog-to-digital conversion

A monolithically integrated optical receiver and a 4-bit flash analog-to-digital converter, all in InP HBT technology, have been implemented. The optical receiver converts an incoming optical pulse train into an electronic signal and is functional up to 10 Gsps. The electronic input 4-bit flash ADC achieves 3.8 effective bits at low input frequency and 2.1 effective bits at Nyquist input frequency when sampled at 10 Gsps. A 4-bit version has 2.8 effective bits at low-input frequency and 2.4 effective bits at Nyquist-input frequency when sampled at 10 Gsps. The 4-bit ADC operates up to 18 Gsps where it has 1.7 effective bits at Nyquist-input frequency.