M niknejad and b boser 13 hypothetical band gap vbe

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Unformatted text preview: ati, JSSC 7/2001, pp. 1076 curvature corrected CMOS bandgap reference EECS 240 Lecture 8: References © 2006 A. M. Niknejad and B. Boser 13 Hypothetical Band-Gap • VBE has a tempco of -2 mV/°C. If we add this to a multiple of the thermal voltage with positive tempco of 0.085 mV /°C, we can achieve temperature independence. EECS 240 Lecture 8: References © 2006 A. M. Niknejad and B. Boser 14 “CMOS” Bandgap EECS 240 Lecture 8: References © 2006 A. M. Niknejad and B. Boser 15 Bandgap Performance [Nicollini] Supply [Tham] [Malcovati] +/- 5V 3V 1V 6.2V 1.24V 0.54V 24mV 20mV 15ppm/oC 85ppm/oC 7.5ppm/oC 86dB 80dB @ 10kHz 40dB @ 500kHz 212ppm/V at DC 4.8mW 1mW 92µW Output voltage Accuracy (σ) TCF PSRR Power dissipation EECS 240 Lecture 8: References © 2006 A. M. Niknejad and B. Boser 16 Constant gm Reference ωu ∝ g m1 = EECS 240 Lecture 8: References gm CL 1 R © 2006 A. M. Niknejad and B. Boser 17 Reference Distribution • Single shared reference • Current distribution: – Many wires – Increase power dissipation • Voltage distribution: – Susceptible to mismatch – use large VGS in distribution network – Careful supply routing to avoid poor PSRR – Avoid loops in analog supply EECS 240 Lecture 8: References © 2006 A. M. Niknejad and B. Boser 18...
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