Title :
A 6-b, 4 GSa/s GaAs HBT ADC
Author :
Poulton, Ken ; Knudsen, Knud L. ; Corcoran, John J. ; Wang, Keh-Chung ; Nubling, Randy B. ; Pierson, Richard L. ; Chang, Mau-Chung Frank ; Asbeck, Peter M. ; Huang, R.T.
Author_Institution :
Hewlett-Packard Labs., Palo Alto, CA, USA
fDate :
10/1/1995 12:00:00 AM
Abstract :
A GaAs-AlGaAs heterojunction bipolar transistor (HBT) process was developed to meet the speed, gain, and yield requirements for analog-to-digital converters (ADC´s). The HBT has current gain of over 100 and fT and fMAX of over 50 GHz. A 6-b, 4 GSa/s (4 giga-samples/s) ADC was designed and fabricated in this process. The ADC uses an analog folding architecture, includes an on-chip master-slave track-and-hold (T/H) circuit, and provides Gray-encoded digital outputs. The ADC achieves 5.6 effective bits at 4 GSa/s, a faster clock rate than any noninterleaved semiconductor ADC reported to date. It has a resolution bandwidth (the frequency at which effective bits has dropped by 0.5 b) of 1.8 GHz at 4 GSa/s, higher than any published ADC. The chip operates at up to 6.5 GSa/s. GaAs HBT IC´s are especially prone to high operating temperatures. This led to reliability problems that were overcome by the use of a fast DC thermal simulator written for this project. A SPICE model for self-heating effects is also described
Keywords :
III-V semiconductors; SPICE; aluminium compounds; analogue-digital conversion; bipolar integrated circuits; circuit analysis computing; gallium arsenide; heterojunction bipolar transistors; integrated circuit modelling; integrated circuit reliability; thermal analysis; 1.8 GHz; 50 GHz; 6 bit; GaAs-AlGaAs; Gray-encoded digital outputs; HBT ADC; HBT IC process; SPICE model; analog folding architecture; analog-to-digital converters; fast DC thermal simulator; heterojunction bipolar transistor; onchip master-slave track/hold circuit; reliability; self-heating effects; Analog-digital conversion; Bandwidth; Circuits; Clocks; Frequency; Gallium arsenide; Heterojunction bipolar transistors; Master-slave; SPICE; Temperature;
Journal_Title :
Solid-State Circuits, IEEE Journal of
