A methodology for the offset simulation of comparators achim graupner zmd ag, dresden this paper introduce a method allows the circuit designer to more fully explore the design space and. Improved performance of dynamic latched comparator for ptl clock gating circuit dinesh kumar ghoghia. Closedloop simulation method for evaluation of static offset in discretetime comparators a. Offset associated with a specific amp can be cancelled by storing it in series with either the input or the output of that stage offset can be cancelled by adding a pair of auxiliary inputs to the amplifier and storing the offset on capacitors connected to the aux.
Springer series in advanced microelectronics, vol 50. Characterizing isf in simulation and measurement fig. The proposed procedure is based on a closedloop algorithm which forces the input. Summary last lecture university of california, berkeley. Offset if operating as a sense amplifier or a comparator, the strongarm latch must achieve a sufficiently small inputreferred offset voltage. The nominal fullscale is related to the supply and the accuracy is set by the comparator offset uncertainty. In this thesis, different comparator architectures and offset calibration techniques will be described, analyzed and compared. The proposed offset calibration technique can greatly reduce the. Some comparators are clocked and only provide an output after the. Latched comparator eecs instructional support group. Cmos comparators 1 performance characteristics a comparator detects if its input voltage or current is higher or lower than a reference level. A comment on how to find the offset of an amplifiercomparator, part a. Design and analysis of double tail comparator using.
Lowpower cmos clocked comparator with programmable. Output of a comparator without hysteresis showing multiple transitions near threshold time s. Effect of apparent offset in discretetime comparators. Design of lowoffset voltage dynamic latched comparator. Closedloop simulation method for evaluation of static offset. Simulations show that this novel dynamic latch comparator designed in 0. Simulation results of comparator parameter value voltage gain 2000 offset voltage 2. Im trying to model a comparator circuit we had to build for a lab in my electronics and circuits course using an opamp and potentiometer.
Use this utility to find the optimum resistors for hysteresis circuit from the resistor sequence. The paper is organized in 5 sections, in section ii we present the resistive divider comparator 3 static operation and input offset voltage, while in. As explained in the previous section, the precharge action of ss 14 in figure 1b keeps m 36m off initially, thereby reducing their offset contribution. An analysis of latched comparator offset due to load capacitor mismatch, ieee trans. Murmann, an analysis of latch comparator offset due to load capacitor mismatch. The comparator can handle the input voltage within railtorail range and is capable of working in temperature range from. Its output is a large voltage which is assumed to represent a digital 1 or 0 level. Tanner software pre layout simulationis used for simulation. But i encounter problem when i want to simulate a clocked comparator using hspice. Ii existing comparators clocked regenerative comparators have. Simulation results show that the offset voltage was easily reduced by 41% while maintaining the same silicon area. I couldnt get the dc transfer characteristics of an output voltage. Analyses and design strategies for fundamental enabling.
An ultralow voltage comparator with improved comparison time. Comparator using an op amp not simulating properly. Tanner eda environment is used for the design and simulation for the comparator circuits. The output switches goes low or high when the signal input crosses the reference voltage. Understanding highspeed signals, clocks, and data capture.
This paper presents a simulation based method for evaluating the static offset in discretetime comparators. The comparator is intended to be employed in an onchip energy harvester system with minimized quiescent current consumption. Vcm proposed comparator the proposed comparator using a new dynamic offset cancellation technique is shown in figure4 and figure5 shows its transient response obtained from simulation. Conventionally, to decrease the offset voltage, a preamplifier has been utilized. A small step signal is applied to the comparator at time. See the complete profile on linkedin and discover hayks. A magnitude digital comparator is a combinational circuit that compares two digital or binary numbers consider a and b and determines their relative magnitudes in order to find out whether one number is equal, less than or. An ultra lowvoltage railtorail comparator for onchip. As a result, offset voltage can be reduced or cancelled with proper transistor sizingmatching during the design process against mismatch and process variation.
To reduce the simulation time during the offset evaluation, we have developed a closedloop method based on a binary search algorithm which shows a fast convergence to the actual comparator threshold. If i were to simulate for offset voltage of a normal comparator, the simulation works fine. A simulation method for accurately determining dc and dynamic offsets in comparators. Noiseaware simulation based sizing and optimization of clocked comparators. Simple highresolution bargraph display architecture uses. A methodology for the offsetsimulation of comparators. Boxandwhisker plot showing monte carlo simulation results for nor and nand.
Engineering strategic research program under r263000a02731. Abstractthis paper addresses an offsetcompensated com. Design of high speed and low offset dynamic latch comparator in. These are usually a reference voltage and a signal from a sensor. Cmos comparators 15 the clock feedthrough from s1 and s2 causes the rising of two equivalent offset voltages, v os,1 and v os,2 at the input of a 1 and a 2. A comparative analysis of high speed dynamic comparator in. Table 1 simulation results on evaluation with varying comparator transistor size. Keywords dynamic comparator, monte carlo method, voltage offset. The table based on simulation results of comparator is shown in table1. Hspice simulation software is used for design and analysis of the dynamic comparator circuits in the above. A low offset dynamic comparator with morphing amplifier. Comparators often employ some hysteresis or some clever clocking scheme to reduce power dissipation or offset. The proposed comparator will be low power comparator compared to all comparator mentioned here.
Probability is 0 of having the initial offset be exactly 0 dynamic comparator will always make a decision but, if the offset is sufficiently close to 0, it may take a long time to make a. The comparator relies on the very high open loop gain of the op amp. Offsetcompensated comparator with fullinput range in. Analysis and design of high speed low power comparator in. Depending on the nature, functionality and inputs, comparators are classified. Offsetcompensated comparator with fullinput range in 150nm fdsoi cmos3d technology. Im designing a double tail dynamic comparator using cadence 180nm technology. Dynamic comparators are widely used in the design of highspeed adcs.
Design and analysis of double tail comparator using adiabatic logic. Here is a waveform you could use to check the offset of a clocked comparator. Figure 5 clocked comparator ltv model characterizing comparator isf using cadence the method for characterization of a comparators isf can be found in 2. We apply a small step to the comparator input at time. Circuitlab is an inbrowser schematic capture and circuit simulation software tool to help you rapidly design and analyze analog and digital. Comparator offset measurement by integrator veriloga model. Design and simulation of a high speed cmos comparator 77 the double tail comparator offers a large current in the regenerative stage for fast re generation and enables less current in the input differential stage to reduce offset. Double tail comparator is a clocked regenerative comparator mostly used due to the ability of fast decisions making because of. Comparison of the proposed comparator with existing double tail comparator is performed and the. Differential reference m7, m8 operate in triode region preamp gain 10 input buffers suppress kickback. Lewisgray dynamic comparator was analyzed using the balanced method and redesigned to minimize its offset voltage. How can someone find out resolution of comparator in cadence.
Closedloop simulation method for evaluation of static. Pdf noiseaware simulationbased sizing and optimization. Abstractthis paper presents a simulationbased method for evaluating the static offset in. How to simulate the offset of the clocked comparator. A study on comparator and offset calibration techniques in. This erratic transitioning near the threshold would cause the valve or motor to be turned on and off multiple times during the critical transition. I want to use a cmos dynamic latch based comparator for my design.
Study of different types of analog comparator topologies. Pdf analyses of static and dynamic random offset voltages in. A clocked comparator is a circuit element that makes decision. A study on the offset voltage of dynamic comparators.
A clocked comparator model based on the isf bandwidth is found from the fourier transform of the isf. Download limit exceeded you have exceeded your daily download allowance. Hi everyone, i am designing a high speed clocked comparator. A bandgap voltage reference is one of the core functional blocks in both analog and digital systems. Design and simulation of a high speed cmos comparator. In this we will simulate all types mentioned types of comparators and analyze them on the basis of different characteristics of comparator like. Comparators are important elements in modern mixed signal systems. But im some difficulties of determining input referred offset.
An analysis on the delay of the comparator will presented. Wang, xilu, a low offset dynamic comparator with morphing amplifier 2017. Understanding highspeed signals, clocks, and data capture by ian king, applications engineer no. This page is a web application that design a comparator circuit with hysteresis. A simulation method for accurately determining dc and. Now i want to simulate for offset voltage using hspice. It consists of double tail latched comparator, offset cancellation capacitors. Offset voltage is the main limitation of designing a dynamic latch comparator. A comment on how to find the offset of an amplifier. Furthermore, consider that the comparator output could be used to control a motor or valve. Depending on applications, an extra driver may be needed to generate vcm. Analysis and design of a lowvoltage lowpower doubletail comparator introduction the comparator compares the voltages that appear at their inputs and outputs a voltage representing the sign of the net difference between them. View hayk dingchyans profile on linkedin, the worlds largest professional community. Analysis and design of high speed low power comparator in adc 1abhishek rai, 2b ananda venkatesan.
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