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New Low-Voltage Low-Power Voltage Reference Circuit

IP.com Disclosure Number: IPCOM000211204D
Publication Date: 2011-Sep-27
Document File: 5 page(s) / 123K

Publishing Venue

The IP.com Prior Art Database

Abstract

A new low-voltage low-power voltage reference circuit is presented in this paper. It can generate a reference voltage with lower current consumption (<1uA) at low power supply voltage from 0.8V to 2.0V using only MOS transistors. The proposed circuit uses less current branches and doesn’t use large resistors and OPA, therefore it saves on current and area.

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New Low-Voltage Low-Power Voltage Reference Circuit

Abstract  -A new low-voltage low-power voltage reference circuit  is presented in this paper. It can generate a reference voltage with lower current consumption (<1uA) at low power supply voltage from 0.8V to 2.0V using only MOS transistors.  The proposed circuit uses less current branches and doesn’t use large resistors and OPA, therefore it saves on current and area.

Body

•          What problem does the proposed circuit solve 

   The proposed circuit can generate a reference voltage with lower current consumption (<1uA) at low supply voltage from 0.8V to 2.0V using only MOS transistors.  The reference voltage is insensitive to temperature, process corner and supply voltage.  The proposed voltage reference circuit uses less current branches and doesn’t require large resistors and OPA, therefore it has reduced current consumption and requires less area.

   The proposed circuit can solve the following problems, which maybe encountered in a low voltage reference circuit design:

      (1)When process doesn’t provide NPN bipolar; if using MOS transistor instead of bipolar transistor, the large threshold voltage variation due to process corner leads to significant variation of reference voltage.

      (2) Low power supply reference circuit may require more current branches.

      (3) Low power supply reference circuit may need very large resistors (larger than 1M ohms) to decrease current consumption;

      (4) Low power supply reference circuit may require a complex circuit architecture, which usually requires an OPA.

•          What is the solution of the proposed circuit

The reference voltage provided by the proposed circuit is based on the difference of gate-source voltage (ΔVgs) between high threshold NMOS and low threshold NMOS, which are operating in the sub-threshold range.  The circuit configuration is shown in Fig.1.

      For NMOS working in the sub-threshold range, the relation of drain current Id and gate-source voltage Vgs meets Eq.1 when drain-source voltage Vds>3*kT/q,  

         

         

      where ξ,I0 is constant, Vth is threshold voltage.

      For a high threshold NMOS M1 and a low threshold NMOS M1A, which are operating in the sub-threshold range, if their drain currents are equal, the difference between their Vgs can be derived from Eq.1,

As shown in Eq.2, VthM1-VthM1A has a stable negative temperature coefficient in different process corners.  By choosing appropriate transistor ratios (PM1A/PM1), the positive and negative temperature coefficients can be compensated for to achieve a ΔVgs with zero-temperature coef...