An accurate current source with on-chip self-calibration circuits for low-voltage current-mode differential drivers

An accurate CMOS current source for current-mode low-voltage differential transmitter drivers has been designed and fabricated. It is composed of binary weighted current mirrors with built-in self-calibration circuits. The proposed self-measurement and calibration circuits can calibrate upon the collective effects of different error contributors due to process, power supply, and temperature variations. The design has been fabricated in standard 0.35-μm CMOS technology. Measurement results show that the differential output voltage can be self-calibrated to ±1% accuracy with 16% reference current variation, 60% power supply variation, or 13% load resistance variation, respectively.