The Effect of Technology Scaling on Power Dissipation in Analog Circuits

Abstract

A general approach for Power Dissipation estimates in Analog circuits as a function of Technology scaling is introduced. It is shown that as technology progresses to smaller dimensions and lower supply voltages, matching dominated circuits are expected to see a reduction in power dissipation whereas noise dominated circuits will see an increase. These finds are applied to ADC architectures like Flash and Pipeline ADC's and it is shown why Pipeline ADC's survive better on a high, thick-oxide supply voltage whereas Flash ADC's benefit from the technology's thinner oxides. As a result of these calculations an adaptation to the most popular Figure-of-Merit (FOM) for ADC's is proposed.

Towards Power Centric Analog Design

“…These analyses of power consumption in analog circuits were further developed by Enz and Vittoz [11]. Later, Bult [12] and Annema et al [13] looked into the effect of scaling on analog power consumption, an analysis which Bult then developed into a more comprehensive analysis of analog power consumption [14]. More recently, Sundström et al, presented a quantitative analysis of the lower bounds of the power consumption of analog-to-digital converters [15].…”

“…Bult [14] used the same scheme as this one, but extended it to include more circuit specifications. He showed that not only thermal noise, but also 1/f noise and circuit matching will put demands on the capacitance.…”

“…Power consumption can be understood in terms of a minimum capacitance requirement, and the current required driving that capacitance. The capacitance is given by technology, thermal noise, 1/f -noise, and matching (in terms of offset or gain matching) [14,15,16]. And the current is controlled by this minimum capacitance, combined with the requirements on speed (in terms of bandwidth, sampling rate or slew rate), settling accuracy, and distortion (in terms of second order or third order distortion with or without feedback) [14,15].…”

“…Therefore it is very difficult to formulate a general description of the power consumption of analog circuits. Still, we believe that the descriptions above, together with the ideas formulated in [14], could be the first elements of such a general description, although many aspects of analog circuits are left to be investigated.…”

“…We also need to understand the power cost for linearity improvement through feedback or other circuit tricks. Matching requirements are sometimes quite expensive in power, particularly regarding offset [14]. Therefore we need compensating techniques, as offset compensation, offset and gain calibration, etc., and we need to understand the power cost for such techniques.…”