scholarly journals A VCO-Based CMOS Readout Circuit for Capacitive MEMS Microphones

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4126 ◽  
Author(s):  
Andres Quintero ◽  
Fernando Cardes ◽  
Carlos Perez ◽  
Cesare Buffa ◽  
Andreas Wiesbauer ◽  
...  

Microelectromechanical systems (MEMS) microphone sensors have significantly improved in the past years, while the readout electronic is mainly implemented using switched-capacitor technology. The development of new battery powered “always-on” applications increasingly requires a low power consumption. In this paper, we show a new readout circuit approach which is based on a mostly digital Sigma Delta ( Σ Δ ) analog-to-digital converter (ADC). The operating principle of the readout circuit consists of coupling the MEMS sensor to an impedance converter that modulates the frequency of a stacked-ring oscillator—a new voltage-controlled oscillator (VCO) circuit featuring a good trade-off between phase noise and power consumption. The frequency coded signal is then sampled and converted into a noise-shaped digital sequence by a time-to-digital converter (TDC). A time-efficient design methodology has been used to optimize the sensitivity of the oscillator combined with the phase noise induced by 1 / f and thermal noise. The circuit has been prototyped in a 130 nm CMOS process and directly bonded to a standard MEMS microphone. The proposed VCO-based analog-to-digital converter (VCO-ADC) has been characterized electrically and acoustically. The peak signal-to-noise and distortion ratio (SNDR) obtained from measurements is 77.9 dB-A and the dynamic range (DR) is 100 dB-A. The current consumption is 750 μ A at 1.8 V and the effective area is 0.12 mm 2 . This new readout circuit may represent an enabling advance for low-cost digital MEMS microphones.

2012 ◽  
Vol 2012 (HITEC) ◽  
pp. 000245-000252 ◽  
Author(s):  
Bruce W. Ohme ◽  
Mark R. Larson

Initial test results have been previously reported for a high-temperature (225°C) 12-bit analog-to-digital converter (HTADC12) fabricated using a production high-temperature silicon-on-insulator (SOI) CMOS process and assembled in hermetically sealed ceramic packages (ref. 1). Reliability test results for the HTADC12 are presented including parametric and functional test results from 1500 hours of dynamic life test at 250°C as well 1000 temperature cycles from −65°C to 200°C. Results of post-stress wirebond, and die bond testing are also provided.


Electronics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 137 ◽  
Author(s):  
Bo Gao ◽  
Xin Li ◽  
Jie Sun ◽  
Jianhui Wu

The features of high-resolution and high-bandwidth are in an increasing demand considering to the wide range application fields based on high performance data converters. In this paper, a modeling of high-resolution hybrid analog-to-digital converter (ADC) is proposed to meet those requirements, and a 16-bit two-step pipelined successive approximation register (SAR) analog-to-digital converter (ADC) with first-order continuous-time incremental sigma-delta modulator (ISDM) assisted is presented to verify this modeling. The combination of high-bandwidth two-step pipelined-SAR ADC with low noise ISDM and background comparator offset calibration can achieve higher signal-to-noise ratio (SNR) without sacrificing the speed and plenty of hardware. The usage of a sub-ranging scheme consists of a coarse SAR ADC followed by an fine ISDM, can not only provide better suppression of the noise added in 2nd stage during conversion but also alleviate the demands of comparator’s resolution in both stages for a given power budget, compared with a conventional Pipelined-SAR ADC. At 1.2 V/1.8 V supply, 33.3 MS/s and 16 MHz input sinusoidal signal in the 40 nm complementary metal oxide semiconductor (CMOS) process, the post-layout simulation results show that the proposed hybrid ADC achieves a signal-to-noise distortion ratio (SNDR) and a spurious free dynamic range (SFDR) of 86.3 dB and 102.5 dBc respectively with a total power consumption of 19.2 mW.


Symmetry ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 165
Author(s):  
Shouping Li ◽  
Yang Guo ◽  
Jianjun Chen ◽  
Bin Liang

This paper presents a foreground digital calibration algorithm based on a dynamic comparator that aims to reduce comparator offset and capacitor mismatch, as well as improve the performance of the successive approximation analog-to-digital converter (SARADC). The dynamic comparator is designed with two preamplifiers and one latch to facilitate high speed, high precision, and low noise. The foreground digital calibration algorithm provides high speed with minimal area consumption. This design is implemented on a 12-bit 30 MS/s SARADC with a standard 0.13 μm Complementary Metal Oxide Semiconductor (CMOS) process. The simulation Nyquist 68.56 dB signal-to-noise-and-distortion ratio (SNDR) and 84.45 dBc spurious free dynamic range (SFDR) at 30 MS/s, differential nonlinearity (DNL) and integral nonlinearity (INL) are within 0.64 Least Significant Bits (LSB) and 1.3 LSB, respectively. The ADC achieves an effective number of bits (ENOB) of 11.08 and a figure-of-merit (FoM) of 39.45 fJ/conv.-step.


2014 ◽  
Vol 23 (05) ◽  
pp. 1450057
Author(s):  
SAHAR SARAFI ◽  
KHEYROLLAH HADIDI ◽  
EBRAHIM ABBASPOUR ◽  
ABU KHARI BIN AAIN ◽  
JAVAD ABBASZADEH

This paper presents an analog-to-digital converter (ADC), using pipelined successive approximation register (SAR) architecture. The structure which is a combination of SAR-ADC and pipelined ADC benefits from each of their advantages. A new synchronization method is proposed to improve the pipelined SAR-ADC's speed. The proposed method reduces the total conversion without limiting the ADC performance. To evaluate the proposed method a 10-bit 100 MS/s is designed in 0.5 μm CMOS process technology. According to the obtained simulation results, the designed ADC digitizes a 9-MHz input with 54.19 dB SNDR while consuming 57.3 mw from a 5-V supply.


2012 ◽  
Vol 457-458 ◽  
pp. 1122-1128
Author(s):  
Yue Hong Gong ◽  
Min Luo ◽  
Jian Guo Ma

In this paper, a 12 bits pipeline ADC (analog to digital converter) based on digitally assisted backend correction is described and behaviorally modeled in Verilog-A language. The Verilog-A model is simulated with Cadence Spectre simulator. In the traditional use of pipeline ADC, the for-end sample and hold amplifier occupies the most power consumption. To decreases the system power consumption, open-loop amplifier is used in the first residual amplify circuit between first and second stage sub-ADC. To correct the nonlinear error introduced by the open-loop amplifier, backend digitally correction is applied.


Author(s):  
Pradeep Kumar ◽  
Amit Kolhe

This paper describes the design and implementation of a Low Power 3-bit flash Analog to Digital converter (ADC). It includes 7 comparators and one thermometer to binary encoder. It is implemented in 0.18um CMOS Technology. The presimulation of ADC is done in T-Spice and post layout simulation is done in Microwind3.1. The response time of the comparator equal to 6.82ns and for Flash ADC as 18.77ns.The Simulated result shoes the power consumption in Flash ADC as is 36.273mw .The chip area is for Flash ADC is 1044um2 .


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