Field-programmable analog array: Difference between revisions

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A '''field-programmable analog array''' ('''FPAA''') is an [[Integrated circuit|integrated circuit device]] containing computational [[Analog signal|analog]] blocks (CAB)<ref>{{cite journal |last1=Hall |first1=Tyson |last2=Twigg |first2=Christopher |last3=Hassler |first3=Paul |last4=Anderson |first4=David |title=APPLICATION PERFORMANCE OF ELEMENTS IN A FLOATING–GATE FPAA |journal=IEEE-ISCAS 2004 |date=2004 |volume=II |pages=589-592589–592}}</ref><ref>{{cite journal |last1=Baskaya |first1=F. |last2=Reddy |first2=S. |last3=Sung |first3=Kyu Lim |last4=Anderson |first4=D.V. |title=Placement for large-scale floating-gate field-programable analog arrays |journal=IEEE Trans.Transactions on VLSI Systems Aug.|date=August 2006 |volume=14 |issue=8 |pages=906-910906–910 |url=https://www.computer.org/csdl/trans/si/2006/08/01664910-abs.html}}</ref> and interconnects between these blocks offering [[field-programmability]]. Unlike their [[Digital signal|digital]] cousin, the [[Field-programmable gate array|FPGA]], the devices tend to be more application driven than general purpose as they may be [[Current-mode logic|current mode]] or voltage mode devices. For voltage mode devices, each block usually contains an [[operational amplifier]] in combination with programmable configuration of passive components. The blocks can, for example, act as [[Analog adder|summers]] or [[Integrator|integratorsintegrator]]s.

FPAAs usually operate in one of two modes: [[Discrete time and continuous time|''continuous time'' and ''discrete time'']].

*''Discrete-time devices'' possess a [[Clock signal|system sample clock]]. In a [[switched capacitor]] design, all blocks sample their input signals with a [[sample and hold]] circuit composed of a semiconductor switch and a capacitor. This feeds a programmable [[Operational amplifier|op amp]] section which can be routed to a number of other blocks. This design requires more complex [[semiconductor]] construction. An alternative, switched-current design, offers simpler construction and does not require the input capacitor, but can be less accurate, and has lower [[fan-out]] - it can drive only one following block. Both discrete-time device types must compensate for switching noise, aliasing at the system sample rate, and sample-rate limited bandwidth, during the design phase.

*''Continuous-time devices'' work more like an array of [[Transistor|transistorstransistor]]s or op amps which can operate at their full [[Bandwidth (signal processing)|bandwidth]]. The components are connected in a particular arrangement through a configurable array of switches. During [[circuit design]], the switch matrix's [[Parasitic element (electrical networks)|parasitic]] inductance, capacitance and [[Noise (signal processing)|noise]] contributions must be taken into account.

Currently there are very few manufactures of FPAAs. On-chip resources are still very limited when compared to that of an FPGA. This resource deficit is often cited by researchers as a limiting factor in their research.

== Development tools ==

{{RefimproveMore citations needed|section|date=May 2017}}

=== AnadigmDesigner®2 EDA Software ===