A compact low-noise fully differential bandgap voltage reference with intrinsic noise filtering

Abstract

A new architecture for differential bandgap voltage references is presented. The system is based on a switched capacitor amplifier that performs correlated double sampling to cancel offset and reduce flicker noise while maintaining a valid output voltage throughout the clock cycle. The circuit noise is filtered by an intrinsic discrete time low-pass function with tunable cut-off frequency. A prototype designed with 0.18 um CMOS process is described. Preliminary performances are estimated by means of periodic noise analysis carried out with the SpectreRF simulator

Design Techniques for Low-Power and Low-Voltage Bandgaps

“…Figure 6 shows the developed R-BG structure. As a first step, the parameter N = 8 was adopted as a trade-off between minimum current and large ∆V EB (2). This means that ∆V EB = 26 mV•ln(N) = 54 mV, I 1 = 8 × I α •(1+β)/β = 680 nA and R 1 = ∆V EB /I 1 = 81 KΩ.…”

“…Thus, voltage-mode BGs cannot be used, since the natural silicon bandgap voltage of 1.25 V would be higher than the supply. For this reason, to avoid switching structure [1,2], current-mode reverse-BGs (R-BG) are typically used [3][4][5][6][7][8], whose conceptual scheme is shown in Figure 1a. This scheme produces a PVT-independent output voltage V REF by means of the sum of two currents over output resistance R 3 : V T -based (V T = k•T/q) current proportional to absolute temperature (PTAT component, I 1 ) and V EB -based current complementary to absolute temperature (CTAT component, I 2 ).…”