RS trigger based relaxation oscillator for temperature measurement circuit

Resistance-to-time converter is always used for digital temperature measurement. An reset-set （RS） trigger based, relaxation oscillator based temperature measurement circuit, which is used to convert the change of thermistor sensor into a frequency signal for later processing, has been presented in this article. The RS trigger, which is composed of two inverters designed with distinct logical transition threshold voltages by changing the metal-oxide-semiconductor （MOS） transistor gains, has the same function as the Schmitt trigger in the relaxation oscillator. The advantage of the RS trigger based Schmitt trigger is that it reduces the dependence to supply voltage, chip temperature, and process variation. This temperature measurement circuit has been applied in a clinical thermometer chip that can measure temperature to an accuracy of better than 0.05 ℃ down to 1.1 V battery voltage. It is fabricated in 0.5 μm double metal single poly complementary MOS （CMOS） process.     

弛张振荡器在高精度体温计芯片中的应用

设计了一款基于弛张振荡器的温度测量电路,通过参考/感应振荡器电路,将热敏电阻的阻值变化转变成数字化的频率信号送系统处理。弛张振荡器使用了具有施密特触发器相同功能的RS触发器,降低了芯片对工艺的要求,便于在低电压和宽温度范围正常工作。该温度测量电路被成功地应用于一款便携式电子体温计芯片,芯片采用0.5μm 1.5 V DMSP CMOS工艺,面积为1 250μm×1 260μm,在1.1 V的低电压下测量精度高达0.05°C,工作电流为30μA,待机电流为0.2μA。     

A coupled sawtooth oscillator combining low jitter with highcontrol linearity

A new type of relaxation oscillator is presented that combines excellent control linearity with low timing jitter. By using an alternative for the Schmitt trigger, the jitter caused by threshold level noise can be significantly reduced compared to a conventional relaxation oscillator, under equal conditions of control linearity. Circuits realized in a 0.8-μm CMOS process show a typical measured distortion in the control characteristic of HD₂ = -67 dB and HD₃ = -90 dB (Δf = 500 KHz), without using any feedback linearization techniques. The measured phase noise is -102 dBc/Hz at 10-kHz offset at f_osc = 1.5 MHz (65-ppm rms jitter) for a total supply current of 360 μA     

An optically controllable negative resistance circuit constructed with optocouplers

An optocoupler with a Darlington configuration at the output side can be used as a one port active device with a current-controlled negative resistance by simply connecting the input and output sides in cascade. The author proposes an optically controllable negative-resistance circuit constructed with optocouplers. The breakover voltage and the holding current of the negative-resistance characteristics can be controlled widely with two external light inputs. Hence, the circuit may be applied to optronic functional switching operations. It is demonstrated that an optically controlled relaxation oscillator can be easily constructed using the circuit, and that applications of the relaxation oscillator to a light modulator and an optical Schmitt trigger can be realized by simple circuit configurations.     

一种用于DC-DC转换器的精密振荡器设计

提出了一种用于DC-DC转换器的高频、精密张驰振荡器的设计方法.基于V-i转换器原理,设计了精密电流产生电路;基于基极电流补偿技术,设计了一种结构新颖的比较器门限电压产生电路,从而有效地提高了振荡器频率稳定性和精度.通过外接可调电阻,振荡器可调工作频率为100 kHz～3 MHz,并能同时提供占空比85%的方波信号和用于斜率补偿的锯齿波信号,还具有与外接时钟信号同步振荡的功能.流片测试结果表明该振荡器满足设计指标.     

A high-speed differential CMOS Schmitt trigger with regenerative current feedback and adjustable hysteresis

This paper presents a brief overview of Schmitt triggers and proposes a new differential current-feedback Schmitt trigger. The hysteresis of the proposed Schmitt trigger is generated using regenerative current feedback and can be adjusted by varying the current of the regenerative feedback network. The center of the hysteresis can also be adjusted by varying the common-mode input voltage. The proposed Schmitt trigger has the characteristics of current-mode circuits, making it particularly attractive for low-voltage high-speed applications. The proposed Schmitt trigger has been designed in TSMC-0.18 μm 1.8 V CMOS technology and analyzed using Spectre from Cadence Design Systems with BSIM3V3 device models. Simulation results are presented.     

Design techniques for ASK demodulators of passive wireless microsystems: a state-of-the-art review

This paper presents a brief overview of Schmitt triggers and proposes a new differential current-feedback Schmitt trigger. The hysteresis of the proposed Schmitt trigger is generated using regenerative current feedback and can be adjusted by varying the current of the regenerative feedback network. The center of the hysteresis can also be adjusted by varying the common-mode input voltage. The proposed Schmitt trigger has the characteristics of current-mode circuits, making it particularly attractive for low-voltage high-speed applications. The proposed Schmitt trigger has been designed in TSMC-0.18 μm 1.8 V CMOS technology and analyzed using Spectre from Cadence Design Systems with BSIM3V3 device models. Simulation results are presented.     

Design and Enactment of Diverse Low Power Techniques Based Schmitt Trigger

In the present-day VLSI system, low power design plays a noteworthy role. As we know that, a circuit with higher power consumption can ruin the performance of the system because in the modern world most of the systems are portable. Subsequently, they are functioned by the batteries. Therefore, it is desirable to have a system which operates at lower supply voltages along with maintaining the performance of the system. This low power system can be attained by abating the leakages of the devices up-to an enormous magnitude. In the contemporary VLSI system, a major role is being contributed by the Schmitt trigger circuit. Schmitt trigger is fundamentally a comparator. It is implemented by using a positive feedback. The Schmitt trigger circuit is used in various devices such as buffer, sub-threshold SRAM, sensors and PWM circuit. It is also used in analog to digital converter. The most significant property of the Schmitt trigger is that they provide hysteresis in their voltage transfer curve. Consequently, they provide better noise immunity as compared to their counterparts. Therefore it becomes quite important to enhance the performance of the Schmitt trigger circuit. The power dissipation of the device can be minimized by minimizing the sub-threshold current. The Schmitt trigger circuit is very imperative in producing a clean pulse from the input signal comprising of noise. There are various applications of Schmitt trigger circuit such as in scheming the oscillator circuit, analog to digital converter, function generator, signal conditioning and numerous applications. Thus, it becomes noteworthy to boost its performance by plummeting the leakages and power consumption of the Schmitt trigger circuit. We have realized the Schmitt trigger circuit by the use of FinFET. Therefore, we have got some optimum output in the parameters such as hysteresis width, power consumption and total noise of the Schmitt trigger circuit, but the leakages have been augmented. Thereafter, we have implemented several techniques on the Schmitt trigger circuit to shrink the leakage current, leakage power and other parameters further. We have applied Self Controllable Voltage Level, Adaptive voltage level and MTCMOS technique on the Schmitt trigger circuit using FinFET to further augment the presentation. All the circuits have been simulated in the virtuoso tool of the cadence in 45 nm VLSI domain. We have applied 0.7 V of the supply voltage to perform the simulation and got some tremendous outcome.     

一种温度不敏感频率范围宽的三角波振荡器

本文介绍了一种由双比较器型施密特触发器构成的三角波振荡器电路,它通过对电容恒流充放电产生对称三角波;此电路的优点是其产生的三角波的频率稳定且具有很高的精度,并对温度和电源的变化不敏感;文章最后给出了电路的Hspice仿真结果。     

Differential CMOS Schmitt trigger with tunable hysteresis

This letter presents a new differential Schmitt trigger with tunable hysteresis. The hysteresis is generated using a cross-coupled inverter pair. The amount of hysteresis can be adjusted by varying the current of the symmetrical load. The proposed Schmitt trigger has been designed in TSMC-0.18 μm 1.8 V CMOS technology and analyzed using Spectre from Cadence Design Systems with BSIM3V3 device models. Simulation results demonstrate that the triggering voltage of the Schmitt trigger can be adjusted from 0.95 to 1.35 V approximately.     

利用差频电路实现微电容式传感器检测电路的温漂抑制

介绍了一种本实验室开发的CMOS工艺的电容式传感器的接口电路。重点分析了基于施密特触发器的张弛振荡器接口电路,实现了敏感电容以及参考电容与频率的转换。通过对两频率求差来抑制各种共模干扰。对样片进行了测试,输出频率与理论值基本一致。最后对该电路进行了温漂特性的仿真和测试,验证了差频电路可以将电源波动和温度的影响完全抑制在精度的允许范围内。     

Memristor Based Pulse Train Generator

Russian Microelectronics - The memristor pulse series oscillator based on the Schmitt trigger with a memristor and a capacitor at the input is discussed. It is shown that such circuit provides the...     

A new Schmitt trigger circuit in a 0.13-/spl mu/m 1/2.5-V CMOS process to receive 3.3-V input signals

A new Schmitt trigger circuit, which is implemented by low-voltage devices to receive the high-voltage input signals without gate-oxide reliability problem, is proposed. The new proposed circuit, which can be operated in a 3.3-V signal environment without suffering high-voltage gate-oxide overstress, has been fabricated in a 0.13-/spl mu/m 1/2.5-V 1P8M CMOS process. The experimental results have confirmed that the measured transition threshold voltages of the new proposed Schmitt trigger circuit are about 1 and 2.5 V, respectively. The new proposed Schmitt trigger circuit is suitable for mixed-voltage input-output interfaces to receive input signals and reject input noise.     

Simple approximation for Schmitt trigger characteristics

A formula is proposed for the input-output characteristic of a Schmitt trigger. Using a single parameter, the formula can fit a variety of practical Schmitt trigger characteristics.     

基于神经元MOS器件的施密特触发器设计

为实现施密特触发器低功耗、回差可控,将神经元MOS器件的控阈技术用于施密特触发器的设计中,设计出基于神经元MOS器件的施密特触发器,并且进一步提出了外部可控回差的施密特触发器的设计.通过HSPICE对电路进行模拟,实验表明此设计仅需2个MOS管,功耗降低30%.并且这种通过改变外部电压值调整回差电压大小的方法比以往的方法更为方便实用.     

A Simple Schmitt Trigger Circuit with Grounded Passive Elements and Its Application to Square/Triangular Wave Generator

This paper introduces a new simple Schmitt trigger circuit using a plus-type differential voltage-current conveyor (DVCC+) and only two grounded resistors. The proposed circuit is very simple and enjoys adjustable lower and higher threshold voltages as well as the output saturation levels. The application of the proposed Schmitt trigger circuit to the square/triangular wave generator is also given. Moreover, a current feedback operational amplifier (CFOA)-based square/triangular wave generator is derived from the proposed DVCC+-based circuit. Simulation and experimental results are presented to exhibit the performance of the proposed circuits.     

Novel CMOS Schmitt trigger

A novel CMOS Schmitt trigger circuit has been realised, using only five MOS transistors. The circuit always guarantees hysteresis, even with very large process variations. The switching speed of the new Schmitt trigger is higher, compared to previously reported CMOS Schmitt triggers.     

Wide Voltage Input Receiver with Hysteresis Characteristic to Reduce Input Signal Noise Effect

In this paper, an input receiver with a hysteresis characteristic that can work at voltage levels between 0.9 V and 5 V is proposed. The input receiver can be used as a wide voltage range Schmitt trigger also. At the same time, reliable circuit operation is ensured. According to the research findings, this is the first time a wide voltage range Schmitt trigger is being reported. The proposed circuit is compared with previously reported input receivers, and it is shown that the circuit has better noise immunity. The proposed input receiver ends the need for a separate Schmitt trigger and input buffer. The frequency of operation is also higher than that of the previously reported receiver. The circuit is simulated using HSPICE at 0.35‐μm standard thin oxide technology. Monte Carlo analysis is conducted at different process conditions, showing that the proposed circuit works well for different process conditions at different voltage levels of operation. A noise impulse of (V_CC/2) magnitude is added to the input voltage to show that the receiver receives the correct logic level even in the presence of noise. Here, V_CC is the fixed voltage supply of 3.3 V.     

Subthreshold Schmitt trigger using body-bias technique for ultra low power and high performance applications

Digital subthreshold logic provides extremely low power consumption since the power supplies are kept below the threshold voltage and using the small subthreshold current of MOS transistors to operate. In this paper, a body-bias technique to match the subthreshold currents of both the NMOS and PMOS transistors is explored and a Schmitt trigger circuit employing this bias technique is proposed. Extensive circuit simulations were conducted and the results were compared with standard body bias technique in terms of performance parameters. The simulation results were obtained with 0.18 μm technology parameters. The conclusion is that Schmitt trigger with this body biasing is suitable for high performance and ultra low power applications.