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 应用科技  2018, Vol. 45 Issue (3): 35-39  DOI: 10.11991/yykj.201708007 0

### 引用本文

LIAO Luwei, FENG Quanyuan. All-MOS voltage reference for passive tag[J]. Applied Science and Technology, 2018, 45(3), 35-39. DOI: 10.11991/yykj.201708007.

### 文章历史

All-MOS voltage reference for passive tag
LIAO Luwei, FENG Quanyuan
Institute of Microelectronics, Southwest Jiaotong University, Chengdu 611756, China
Abstract: The traditional reference source has a large power consumption and territory area, therefore, it is inapplicable for the design of the passive tag in the ultrahigh RFID technology. A voltage reference source with low voltage, low power consumption, without operational amplifier and constituted by all-MOS tube was designed, a new all-MOS tube reference core circuit was proposed. The temperature property is excellent. A pre-stabilized voltage circuit was added, the traditional design of operational amplifier was abandoned and the PSRR was increased. Simulation results showed that, at the typical supply voltage of 1.5V, the output of voltage reference was 619mV and the static power consumption was 1.8 μW; at 1.5 V~5 V, the voltage reference changed by 22 μV, the linear regulation rate was 4.9 μV/V; at low frequency, the PSRR was as high as −102 dB; within the scope of −20℃~120℃, the temperature coefficient was 6.2 ppm/℃. The proposed design is especially applicable for the chip of the ultrahigh RFID tag requiring low cost and low power consumption.
Key words: voltage reference    RFID tag    passive tag    power supply rejection ratio (PSRR)    linear regulation rate    temperature coefficient    low voltage    low power consumption

1 亚阈值基准原理分析 1.1 传统亚阈值基准结构

 ${I_{{\rm{DS}}}} = \mu {C_{{\rm{OX}}}}V_{\rm{T}}^2\frac{W}{L}\exp (\frac{{{V_{{\rm{GS}}}} - {V_{{\rm{TH}}}}}}{{m{V_{\rm{T}}}}})$ (1)

 ${V_{{\rm{GS}}}} = {V_{\rm{T}}}\ln (\frac{{{I_{{\rm{DS}}}}}}{{\mu {C_{{\rm{OX}}}}V_{\rm{T}}^2}}\frac{L}{W}) + {V_{{\rm{TH}}}}$ (2)

 ${V_{{\rm{GS1}}}} - {V_{{\rm{GS2}}}} = {V_{\rm{T}}}\ln \frac{{{\eta _2}}}{{{\eta _1}}}$

 ${I_{{\rm{BIAS}}}} = \frac{{{V_{\rm{T}}}\ln ({\eta _2}/{\eta _1})}}{{{R_1}}}$ (4)

M3处于饱和区，其VGS

 ${V_{{\rm{GS_3}}}} = {V_{_{{\rm{TH}}}}} + \sqrt {\frac{2}{{\mu {C_{{\rm{OX}}}}{\eta _3}}}\frac{{\lambda {V_{\rm{T}}}\ln n}}{{R1}}}$

 ${V_{{\rm{REF}}}} = {V_{{\rm{TH}}}} + \sqrt {\frac{2}{{\mu {C_{{\rm{OX}}}}{\eta _3}}}\frac{{\lambda {V_{\rm{T}}}\ln n}}{{{R_1}}}} + \frac{{\lambda {V_{\rm{T}}}\ln n}}{{{R_1}}}{R_2}$ (6)

MOS管的阈值电压可近似为线性负温度系数[11]，即式(4)第一项为负温度项，后两项均为正温度项，因此可以得到温度系数较小的基准电压源。但是片上电阻和电子迁移率μ都有一定的温度特性，使得传统亚阈值基准电压的温度系数很难把控，同时片上电阻消耗大量的版图面积。

1.2 全MOS基准核心电路设计

M3的导通电阻为

 ${R_{{\rm{on_3}}}} = \frac{1}{{\mu {C_{{\rm{OX}}}}{\eta _3}({V_{{\rm{GS_7}}}} - {V_{{\rm{TH}}}})}}$ (7)

 ${I_{{\rm{BIAS}}}} = \mu {C_{{\rm{OX}}}}{\eta _3}({V_{{\rm{GS7}}}} - {V_{{\rm{TH}}}}){V_{\rm{T}}}\ln \frac{{{\eta _2}}}{{{\eta _1}}}$ (8)

M7的栅源电压关于偏置电流的表达式为

 ${V_{{\rm{GS_7}}}} = {V_{{\rm{TH}}}} + \sqrt {\frac{{2{I_{{\rm{DS}}}}}}{{\mu {C_{{\rm{OX}}}}{\eta _7}}}}$ (9)

 ${I_{{\rm{BIAS}}}} = \frac{{4\mu {C_{{\rm{OX}}}}\eta _3^2}}{{{\eta _7}}}{[{V_{\rm{T}}}\ln \frac{{{\eta _2}}}{{{\eta _1}}}]^2}$ (10)

 ${V_{{\rm{GS_7}}}} = {V_{{\rm{TH}}}} + \frac{{4{\eta _3}\ln ({\eta _2}/{\eta _1})}}{{\sqrt {{\eta _7}} }}{V_{\rm{T}}}$

M5和M6栅源电压差值为

 ${V_{{\rm{GS_5}}}} - {V_{{\rm{GS_6}}}} = {V_{\rm{T}}}\ln ({\eta _6}/{\eta _5})$

 \begin{aligned}{V_{{\rm{REF}}}} = & {V_{{\rm{GS7}}}} - {V_{{\rm{GS6}}}} + {V_{{\rm{GS5}}}} = \\& {V_{{\rm{TH}}}} + \frac{{4{\eta _3}\ln ({\eta _2}/{\eta _1})}}{{\sqrt {{\eta _7}} }}{V_{\rm{T}}} + {V_{\rm{T}}}\ln \frac{{{\eta _6}}}{{{\eta _5}}}\end{aligned} (13)

 $\frac{{\partial {V_{{\rm{REF}}}}}}{{\partial T}} = \beta + [\frac{{4{\eta _3}\ln ({\eta _2}/{\eta _1})}}{{\sqrt {{\eta _7}} }} + \ln \frac{{{\eta _6}}}{{{\eta _5}}}]\frac{k}{q}$

2 基准源系统设计

2.1 启动电路

2.2 预稳压电路设计

 ${i_{14}} = {g_{{\rm{ds14}}}}({v_{{\rm{dd}}}} - {v_{{\rm{pre}}}})$

 ${i_{14}} = \frac{{{v_{{\rm{pre}}}}}}{{{r_{{\rm{eq}}}}}} = {g_{{\rm{ds14}}}}({v_{{\rm{dd}}}} - {v_{{\rm{pre}}}})$ (16)

 $\frac{{{v_{{\rm{dd}}}}}}{{{v_{{\rm{pre}}}}}} = \frac{1}{{{r_{{\rm{eq}}}}{g_{{\rm{ds}}14}}}} + 1 = K$

3 仿真分析