A Digital-Based Virtual Voltage Reference

Abstract

A novel virtual reference concept is introduced in this paper to design accurate, mostly digital, software-defined, process-supply-and-temperature (PVT)-independent voltage references suitable to replace conventional analog reference circuits in present day, low voltage, aggressively scaled, mainly digital integrated systems. The operation and the performance of references based on the proposed approach are tested by computer simulations and experiments carried out on a proof-of-concept, microcontroller-based prototype, reporting a measured thermal drift of 16 in a range from 10 to 100 and a line regulation of 0.15%/V. The advantages in terms of costs and performance of the proposed digital references in comparison with state-of-the-art analog solutions are finally discussed.Index Terms-Digital bandgap circuit, digital-based analog circuits, PVT-independent reference, virtual voltage reference.

All-Digital High Resolution D/A Conversion by Dyadic Digital Pulse Modulation

“…Nonetheless, to get accurate 2 N -level-quantized voltages proportional to a sequence of input codes (i.e. to retrieve the ZOH signal in itself, rather than its baseband component), as often needed in MD/DA AIs [7], the output filter of a DDPM DAC can be designed considering the less stringent quasi-static requirement (12) rather than (17).…”

“…Limiting the analysis, for the sake of simplicity, to a constant input code n (i.e. a periodic DDPM), based on (7) and 9, the error on a DDPM waveform due to power supply fluctuations v dd (t) can be expressed as…”

“…T HE limitations of present-day nano-scale MOS transistors as analog devices [1] have brought an increasing interest towards mostly-digital (MD) [2][3][4][5][6][7][8] and digitally-assisted (DA) [9][10][11][12] analog interfaces (AIs) for present day and future integrated systems. Both MD AIs, where analog signal processing is (almost) completely moved to the digital domain and implemented by synthesizable logic (Fig.1a), and DA AIs, where critical calibration, conditioning, configuration and biasing are managed by a digital unit (Fig.1b), very often rely on accurate monitoring and generation of continuous-inamplitude voltages and currents which require on-chip analogto-digital (A/D) and digital-to-analog (D/A) conversion.…”

“…Analog-to-Digital Converters (ADCs) and Digital-to-Analog Converters (DACs) for MD/DA AIs [13] should be mostlydigital circuits themselves, with a very good static accuracy, intrinsically robust to process variations and mismatch and suitable to be implemented in nanoscale technologies with a minimum overhead in terms of silicon area and power consumption. By contrast, bandwidth and dynamic performance are often not critical [7].…”

A 0.7 V, 2.7 μW, 12.9 ppm/° C over 180° C CMOS subthreshold voltage reference

“…This approach has advantages with respect to power consumption and digital process compatibility, but suffers from TC performance due to the larger non‐linearities of MOSFETs in comparison to bipolar transistors. Alternative modern approaches are utilizing a digital‐based virtual voltage reference , which although promising has a few limitations in terms of area and power consumption due to signal processing requirements.…”