Article key explains multichannel answer collects design consideration of the system with data, and focusing at passing compositive multichannel answer with the input ADC solution answers a space to suffer be restricted to apply (if light is sent and receive implement, can apparel IoT of net of couplet of medical treatment equipment, content and other portable instrument) these technical challenges. Does the solution of low power comsumption that the article offers use compositive formula does multichannel answer use an input 4 passageways / 8 passageways, 16, 250 KSPS PulSAR? ADC AD7682/AD7689, its offer 2.39mm of 2.39mm × dimensions of chip of small-sized brilliant round class is enclosed (WLCSP) , can save 60% above board space, can solve tall passageway density and batteries power supply well the challenge of portable system, have agile configuration and high accuracy property at the same time.
Multichannel answer collects a system with data
The schism sheet passageway that much passageway data collects a system to use different type normally or compositive multichannel answer use and the imitate signal catenary of synchronous sampling comes with of all kinds sensor (what if temperature, pressure, oscillatory sensor is reached,be based on applied requirement is other a lot of. For example: many inputs passageway answer is used to an ADC, each passageway all uses a sampling to maintain amplifier, and many inputs passageway answer is used to an ADC, so that,each passageway all uses an ADC synchronous to each passageway sampling. The first kind of circumstance uses successive to approach normally model (SAR) modulus converter (ADC) , if pursue,1 is shown. It can save power comsumption of quite a few, space and cost, the input end of each passageway may need low fight mix fold filter, its passageway switch and order and ADC changeover time are correct and synchronous. The 2nd kind of circumstance is shown 2 times like the graph, realizable takes in and send out in large quantities rate wants to divide the passageway with synchronous sampling to count, but what still can keep constant between sampling passageway is phasic. If the graph is shown 3 times, certain application asks every passageway uses special amplifier and ADC synchronous to the input sampling, protect phasic information in order to raise the sampling rate of every passageway, cost is board area and power comsumption can increase. Synchronous sampling ADC is used at checking monitoring of line of equipment, power and control of polyphase electric machinery automatically normally, these application ask each passageway says rate with be being swallowed higher successive sampling, in order to protect the phasic concern between the passageway, realize accurate instantaneous to measure.
Graph 1. Simplify much passageway data collects signal catenary — the first kind of circumstance
Graph 2. Simplify much passageway data collects signal catenary — the 2nd kind of circumstance
Graph 3. Simplify much passageway data collects signal catenary — the 3rd kind of circumstance
The ADC amount that the crucial dominant position that multichannel answer uses depends on every passageway needing is less, space, power comsumption and cost are consequently lower. However, multichannel answer takes in and send out in large quantities with systematic realizable rate is equal to onefold ADC to take in and send out in large quantities rate is divided connect number of channels with sampling. SAR ADC is had low defer and dynamic power comsumption and take in and send out in large quantities rate proportionate is inherent advantage. They are commonly used at the passageway answer with the framework, special agree with detect and monitoring function. Light is sent and receive implement the multichannel that module uses answer collect a system to need tall passageway density with data, can apparel small measure of requirement of medical treatment equipment and low power comsumption, the signal that comes from many sensor needs monitoring, many input passageway answer to be used individual or many ADC. One of main challenges that multichannel answer collects a system with data are, when the input switch arrives when below one passageway, it needs to answer the pace that approachs full span range to receive an input quickly, in order to make set-up time or the problem that string together faze is minor change. The multichannel that the introduction is based on SAR framework below answer send and receive with Yu Guang with input ADC implement and can apparel the concrete example of electronic equipment, explained among them why the good choice that AD7689 is this kind of application.
Light is sent and receive implement
100Gbps light is sent and receive implement the market will welcome growth opportunity 10 years in future, because it supports light of high speed be concerned with,transmit. Light is sent and receive implement crucial challenge is the signal that collect and processes wider bandwidth, or it is with lower power comsumption in less space answer with many inputs passageway. Send and receive now implement be in the light of long-range application design at first, dimension, power comsumption and cost structure restricted his to be in the use in net of more sensitive to cost city land with certain boundaries. Net of city land with certain boundaries includes: Metropolis area 500 Km comes to 100 Km of core of 1000 Km, metropolis 500 Km and metropolis receive 100 Km to apply below. Because competition of net of city land with certain boundaries is intense, dimensional excessive price is quite high, make be of exceptional importance of circuit card density, accordingly, of the radial road card of inferior cost or lesser dimension it is more and more important to application of be concerned with to insert the module that receive form.
In optical network, raise 100 Gbps from 10 Gbps as the bit rate of every passageway or taller, element of fiber-optic blame ideal can reduce signal quality badly, affect its to transmit function. Cause light when fiber-optic blemish noise, nonlinear effect and abreaction when waiting for adverse effect, long-distance optical network also can produce technical challenge. To answer these major challenges, a lot of 40 Gbps and 100 Gbps light are sent and receive implement technology of manufacturer use be concerned with will support taller data rate the join, biggest cover limits and longer distance, exceed long-distance network requirement with getting used to city land with certain boundaries to be mixed remotely, remotely. Format of signal of general can integrated multistage mixes technology of be concerned with be concerned with detects, use double polarization, orthogonality and phase shift key to accuse (DP-QPSK) optimizes signal modulation, restrain the fiber-optic effect when taller data rate thereby, make 100 Gbps is transmitted in economically go up with the technology feasible. Next generation 100 Gbps (reach above) data rate light is sent and receive implement will beg lower power comsumption and smaller size, so that increase passageway density, save space, power comsumption and cost considerably. According to specific requirement, the passageway number of optical system is in normally 8 to 64 between. To PCB design personnel character, component is placed and walk along line wiring to become important, especially system of tall passageway density.
Graph 4 showed those who connect consumed module to simplify block diagram, include ITLA of emitter, receiver, miniature among them (compositive and adjustable humorous laser component) collect parts of an apparatus with data. Graph 5 showed miniature ITLA simplify block diagram, it is parts of an apparatus of laser of tuning of electron of a kind of broadband, use at controlling fast wavelengh switch. Emitter includes Mach-Zehnder driver and modulator, control of in order to gives the extent that shoots laser or strength. Multichannel answer is used in control and monitoring a function normally with input ADC, so that to coming from light module is mixed,the data of the many passageways of miniature ITLA undertakes digitlization.
Graph 4. Smooth module simplifies block diagram
Graph 5. Miniature is compositive and adjustable humorous laser component simplifies block diagram
With can apparel style of the equipment life that monitor is asked for
Graph 6 showed the model can apparel the brief block diagram of electronic equipment. Contemporary can apparel electronic equipment is compositive a variety of sensor will monitor human body accurately in real time a variety of biology index. They offer agile user interface to be used at data storage, transmit data computer of individual smartphone, flat or notebook computer through Wi-Fi. This kind of equipment uses impedance of biology potential, biology or smooth sensor to get degree of saturation of oxygen of rate of concerned heartbeat, breath, blood (the information that a variety of life style such as SpO2) collect. Acoustical sensor uses the information that collects concerned blood pressure and dietary activity, temperature sensor is used measure temperature. The inertial motion sensor that is based on MEMS (accelerometer) with will dog daily body activity. The signal that comes from different sensor needs to undertake imitate signature manages, next multichannel answer uses ADC. According to systematic requirement, certain signal still may need to undertake synchronous sampling. ADC undertakes digitlization to these signal subsequently, processor or small controller undertake to its later period is handled finally, extraction concerns the information of all sorts of physiology index.
Graph 6. Can apparel electronic equipment simplifies block diagram
Electrocardiogram (activity of the heart that monitor is used on ECG) tradition, this is monitored to physiology and the heart is diagnosed crucial. However, intelligence can apparel sensor of systematic use light and biology impedance sensor, appearance of custody of supportive general heartbeat is compositive to wrist watch, wrist is taken or the activity is tracked implement etc can apparel in electronic equipment.
In optical system, the surface of infra-red transmittance skin that twinkles quickly, photoelectricity detector measures the light that blood red cell absorbs. Imitate front recuperates this faint signal digitlizes his, use photoelectricity pulse wave next (PPG) technology undertakes an aftertreatment, wait for the information of a variety of physiology variable in order to extract about rate of heartbeat, breath and SpO2.
Compare with the technical photograph such as light, the power comsumption of biology impedance sensor wants low much, can extend time of batteries add boat consequently. Impedance sensor can use biology to measure breathing rate or skin impedance. Through electrode general skin of infuse of signal of a sine (body is organized) , measure, digitlize and the small electric current that the aftertreatment has shed, unscramble all sorts of physiology signal accurately thereby, if breathe electrical conductivity of rate, skin or lobar seeper,wait.
These equipment need are tall compositive degree, price of very sensitive, tall sex is compared, the efficient, batteries power supply in can loading tiny module solution. They must monitor a variety of physiology variable reliably accurately, the bogus that can restrain motion to arise better at the same time resembles and external ambient conditions, otherwise true signal may be flooded by noise, bring about reading not accurate. Accordingly, ADC must have good noise performance, often had used sampling or all be worth a law to improve integral trends range. The target inputs frequency paragraph be arrive from DC 250 Hz, so ADC sampling rate is close to several KSPS.
Compositive multichannel answer with the input 4 passageways / 8 passageways, 16, 250 KSPS ADC
AD7682/AD7689 is the compositive multichannel with bannerer industry answer with the input 4 passageways / 8 passageways, 16, 250 KSPS SAR ADC, use ADI company to only craft of M CMOS of 0.5 μ is made. Compositive 4 passageways / 8 passageways are low multichannel answer uses string of faze implement the adjacent that introduce does not match minimum between the path, support ordinal sampling. The in-house 2.5 V that these ADC allow to choose ultralow temperature to float or 4.096 V nicety are exterior and fiducial voltage source, fiducial voltage source or exterior amortize are fiducial voltage source, piece on the internal temperature model of ADC of temperature sensor monitoring is worth. Such need not exterior component, save PCB area and BOM cost considerably. The buy inside these ADC alignment of a passageway implement, use at one by one or didymous scanning passageway, internal temperature sensor can repeat make can or ban with. Compatible SPI, MICROWIRE, QSPI mixes its agile serial number interface other figure lead plane. The user can configure register 14 times to choose all sorts of option through interior, sensor of source of the passageway number that includes to want sampling, fiducial voltage, temperature and passageway alignment implement. Read after changing mode, changeover take mode and the changeover whole journey that contain or do not contain busy instruction to read take pattern, this interface allows to carry out 4 lines type to read an operation. AD7682/AD7689 suits application of tall passageway density very much, send and receive solely for example implement, can apparel medical treatment equipment and other use at nicety to detect the portable instrument with monitoring.
Graph 7 showed AD7689 uses what passageway data collects a system at a many to simplify block diagram, its provide the agile configuration option that uses easily and nice performance. It can be solved turn the complex design issue related to set-up time with passageway switch, alignment, save design time.
Graph 7. Block diagram of AD7689 representative application (did not show all join are mixed go Ou)
Use application to much passageway, multichannel answer, some designs personnel uses bumper of low output impedance to handle multichannel answer to use implement the reactive influence that inputs end (depend on what use take in and send out in large quantities rate) . The input bandwidth of SAR ADC (tens of MHz) the input bandwidth with ADC driver (tens of going to hundreds MHz) frequency of prep above sampling, and be needed to input signal bandwidth to arrive in tens of Hz normally hundreds KHz limits. Accordingly, according to systematic requirement, multichannel answer is used implement input end may need only the limit low connect RC to fight mix fold filter to eliminate the signal that does not need (mix fold) , prevent its retrace to arrive in target bandwidth, restrict noise thereby and ease set-up time problem. The RC filter value that each input passageway uses should accept or reject under the basis the relation chooses meticulously (because be restricted too much to take,increase lack fidelity) : Capacitance relatively congress conduces to attenuation multichannel answer is used implement reactive influence, but the phasic abundant of class measures before also may be being reduced one amplifier, make its become not stable. To make RC filter has tall Q, low temperature coefficient, and stable electric character is had below metabolic voltage, the proposal uses C0G or NP0 electric capacity. Should choose reasonable series connection resistance, amplifier is stabilized and restrict its in order to maintain to export electricity. Resistance cannot pass big, otherwise multichannel answer is used implement driver of the ADC after recoil will not is opposite capacitance recharge.
AD7682/AD7689 can offer 2.39 Mm of × of 2.39 Mm now, cite a base dimensions of chip of round class of compatible, brilliant is enclosed (WLCSP) , it compares dimensions of chip of casing of down-lead of 4 Mm of × of existing 4 Mm to enclose (LFCSP) or parts of an apparatus of other and congener competition are small 60% above, can realize higher circuit density in very little system space so. The graph is shown 8 times for small-sized WLSCP dimension and dimension of pencil of standard 6 Mm contrast pursues.
Graph 8. Dimensions of chip of AD7682/AD7689 brilliant round class encloses the dimension contrast with standard pencil
The active side of AD7682/AD7689 WLCSP chip is in the opposite, can use solder ball to receive PCB repeatedly, graph the 11 chip dimension after showing PCB is assembled. The actual distance between surface of the chip after PCB is assembled and substrate (from board height) with the block solder net that pressworks to go up in substrate and solder dish the diameter is concerned.
Graph 9. The AD7682/AD7689 WLCSP dimension after PCB is assembled
AD7682/AD7689 needs an imitate and digital kernel power supply (VDD) and input of a number / output interface power source (VIO) , so that be mixed at 1.8 V with any interpose the logistic and direct interface between VDD. VDD and VIO bring the power source amount that the foot also can be together to need in order to save systematic place repeatedly, and they and power source sequential have nothing to do. These parts of an apparatus use 5 V (VDD) and power supply of power source of 1.8 V (VIO) , its power comsumption and take in and send out in large quantities scale of rate thread sex concerns, can realize low-down power comsumption so: Below the case that uses source of fiducial voltage of exterior 5 V, the typical power comsumption when 100 SPS is W of 1.7 μ about, 12.5 MW is when 250 KSPS, if pursue,10 are shown. Accordingly, this ADC is had efficient, to rate of sampling of on any account (low even to several Hz) all suit, can support well portable with batteries power supply system. One of main character of this parts of an apparatus are its can change level in every when the end close automatically, use up low-down to need machine electricity only (typical cost 50 NA) , can save batteries n when using parts of an apparatus consequently, extend time of batteries add boat.
Graph 10. AD7682/7689 job electric current and take in and send out in large quantities the relation of rate
To needing the application of many AD7682/AD7689 parts of an apparatus, use amortize of bumper of in-house and fiducial voltage exterior and fiducial voltage will be more effective, can reduce SAR to change string of faze so. As a result of in-house and fiducial voltage limitation is in 4.096 V, because this uses 5 V function of the SNR when source of exterior and fiducial voltage is optimal. Input signal sound to 2 KHz, use 5 V source of exterior and fiducial voltage and when moving amain with 250 KSPS, it provides outstanding communication and dc performance: INL is ± 1.5 LSB, letter offer is compared (SINAD) is 93 DB about, effective digit (ENOB) is 15.2 about. Graph 11 showed the typical performance that gives the SNR below exterior and fiducial voltage, SINAD and ENOB.
Graph 11. The relation of AD7682/7689 SNR, SINAD and ENOB and fiducial voltage
Next generation insert the light that receive form to send and receive implement module and other portable system need data of efficient, small size, low cost to collect a system. AD7682/AD7689 provides industry bannerer compositive spend and nice performance, support extensive sensor port, design personnel uses these parts of an apparatus to be able to satisfy slashing user requirement not only, return the poor dissimilation that can implement a system. This kind efficient compositive ADC solution can answer a space to accept the tall circuit density that is restricted to apply and challenge of hot power comsumption, compare the space that can save 60% above with existing LFCSP and competitive product photograph, very appropriate to application of rate of sampling of on any account.
(Origin: Yadenuo semiconductor)
