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New Power Saving Design Method for CMOS Flash ADC. Institute of Computer, Communication and Control, Circuits and Systems, July 2004 IEEE 班級 :積體碩一 姓名 :黃順和 學號 : 95662009. outline. 1. Introduction 2. Proposed Method 3. Simulation Results 4. Conclusions 5. References. Introduction.
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New Power Saving Design Method for CMOS Flash ADC Institute of Computer, Communication and Control, Circuits and Systems, July 2004 IEEE 班級 :積體碩一 姓名 :黃順和 學號 :95662009
outline • 1. Introduction • 2. Proposed Method • 3. Simulation Results • 4. Conclusions • 5. References
Introduction • The flash ADC has very high data conversion speed, low-resolution and large chip area along with large power dissipation. • The 2n-1 comparators in flash ADC also cost too large area and lead much power consumption. • we got an idea from bisection method to let only half of comparators working in every clock cycle for reducing the power consumption.
Proposed Method • we use a comparator-based inverter Inv along with an NOMS and a PMOS as switches. • Vin < Vref/2, the upper half of thermometer codes will be set all 0. • Vin > Vref/2, the lower half of thermometer codes will be set all 1.
Simulation Results • The simulations are made in the same condition, that are, input sine-wave signal operating at 20MHz along with Vp-p,=2V,Vref=2V, clock rate at 200MHz, and power supply on 3.3V. • the power consumptions are 71.72mW and 40.75mW from the traditional ADC and our proposed ADC. • Their linearity is well controlled with in ±1LSB.
Conclusions • Our proposed circuit needs only a comparator-based inverter along with an NMOS and a PMOS as switches • The power saving of near 50% matches our prediction that shows the encourage. • The chip size is about 1.4*1.6mm2 in 0.35μm technology and the chip layout is shown in Fig.
References • [1] P. C. S. Scholtens and M. Vertregt, ”A 6-b 1.6-Gsampleh flash ADC in 0.18 pm CMOS using averaging termination,” IEEE Journal of Solid-state Circuits, Vol. 37, Dec. 2002, pp.1599-1609 • [2] Yoo Jincheol, Lee Daegyu, Choi Kyusun and Kim Jongsoo, ”A power and resolution adaptive flash analog-to-digital converter,” International Symposium on Low Power Electronics and Design, Aug. 2002, pp. 233-236. • [3] J. Terada, Y. Matsuya, F. Morisawa and Y.Kado, “8-mW, 1-V, 100-Msps, 6-bit A/D Converter using a trans-conductance latched comparator,” Proceedings of the Second IEEE Asia Pacific Conference on ASIC, Aug. 2000, pp.53-56