collinge@uvicctr.UUCP (Doug Collinge) (05/28/85)
I have a need for a very fast A/D converter. SPECS: 4MHz conversion rate 4 bits resolution binary output I realize that this can be done with discrete comparators, etc. and this is how I am doing it at the moment, but I want more convenience and a lower package count. I also know about the RCA CA3300 but this seems to be unavailable for the near future. Anyone have any tips? -- Doug Collinge School of Music, University of Victoria, PO Box 1700, Victoria, B.C., Canada, V8W 2Y2 decvax!nrl-css!uvicctr!collinge decvax!uw-beaver!uvicctr!collinge ubc-vision!uvicctr!collinge
sct@lanl.ARPA (05/29/85)
> I have a need for a very fast A/D converter. > > SPECS: > 4MHz conversion rate > 4 bits resolution > binary output > > I realize that this can be done with discrete comparators, etc. > and this is how I am doing it at the moment, but I want more > convenience and a lower package count. I also know about the > RCA CA3300 but this seems to be unavailable for the near future. > > Anyone have any tips? Two I have found are the TRW TDC1021 and the TDC1014. Both operate at 25 MegaSamples per second and have been available since 1978. I do not have any price information. >
pda@crystal.UUCP (05/29/85)
> I have a need for a very fast A/D converter. > > SPECS: > 4MHz conversion rate > 4 bits resolution > binary output > > I realize that this can be done with discrete comparators, etc. > and this is how I am doing it at the moment, but I want more > convenience and a lower package count. I also know about the > RCA CA3300 but this seems to be unavailable for the near future. > > Anyone have any tips? > > -- > Doug Collinge > School of Music, University of Victoria, > PO Box 1700, Victoria, B.C., > Canada, V8W 2Y2 > decvax!nrl-css!uvicctr!collinge > decvax!uw-beaver!uvicctr!collinge > ubc-vision!uvicctr!collinge Look into flash encoders. They come in several speeds and resolutions. 4 Mhz would easily be found. There are some up to 100mhz with resolutions up to 8 bits. RCA, TRW and Siemens make a variety of different configurations. A flash encoder is in effect a stack of 2**n comparators with a laser trimmed resistor network for the reference voltage at each comparator. The physical layout of the board around these devices is critical for good performance. They have a tremendous bandwidth and are integrating digital and analog electronics on one board. Watch out for noise to couple through the board grounds and many other places. Paul Anderson University of Wisconsin Computer Sciences Dept. Madison, Wis 53706
mike@amdcad.UUCP (Mike Parker) (05/31/85)
In article <26502@lanl.ARPA>, sct@lanl.ARPA writes: > > I have a need for a very fast A/D converter. > > > > SPECS: > > 4MHz conversion rate > > 4 bits resolution > > binary output > > > > I realize that this can be done with discrete comparators, etc. > > and this is how I am doing it at the moment, but I want more > > convenience and a lower package count. I also know about the > > RCA CA3300 but this seems to be unavailable for the near future. > > > > Anyone have any tips? > > Two I have found are the TRW TDC1021 and the TDC1014. Both operate at > 25 MegaSamples per second and have been available since 1978. I do not > have any price information. > > I tried to e-mail a response but it bounced, so I'll have to clutter the net with it. AMD makes a 4 bit 100Mhz A to D converter. I used to be the applications engineer in charge of it ( two years or more ago ). I think Plessey and Analog Devices also make these parts. National's half-flash should also fit the bill although you'd be throwing away 4 bits. How many do you need, production quantities or one-off quantities? Give me a call and we'll discuss it further. Mike @ AMDCAD 408-749-4947
mike@amdcad.UUCP (Mike Parker) (05/31/85)
In article <465@crystal.UUCP>, pda@crystal.UUCP writes: > > A flash encoder is in effect a stack of 2**n comparators with a laser trimmed > resistor network for the reference voltage at each comparator. The physical > layout of the board around these devices is critical for good performance. They > have a tremendous bandwidth and are integrating digital and analog electronics > on one board. Watch out for noise to couple through the board grounds and many > other places. > > Paul Anderson > University of Wisconsin > Computer Sciences Dept. > Madison, Wis 53706 Actually the board layout at 4 Mhz isn't all that critical. It isn't nearly the problem that noise elimination at 100Mhz presents. Mike @ AMDCAD
simard@loral.UUCP (Ray Simard) (06/02/85)
In article <127@uvicctr.UUCP> collinge@uvicctr.UUCP (Doug Collinge) writes: >I have a need for a very fast A/D converter. > >SPECS: > 4MHz conversion rate > 4 bits resolution > binary output > I recommend the Signetics/N.A. Phillips PNA7507. It affords a 7-bit flash conversion at up to 15 MHz, is monolithic, and costs less than $20 in onesey-twozies. [ I am not a stranger, but a friend you haven't met yet ] Ray Simard Loral Instrumentation, San Diego {ucbvax, ittvax!dcdwest}!sdcsvax!sdcc6!loral!simard ...Though we may sometimes disagree, You are still a friend to me!
pda@crystal.UUCP (06/03/85)
> In article <465@crystal.UUCP>, pda@crystal.UUCP writes: > > > > A flash encoder is in effect a stack of 2**n comparators with a laser trimmed > > resistor network for the reference voltage at each comparator. The physical > > layout of the board around these devices is critical for good performance. They > > have a tremendous bandwidth and are integrating digital and analog electronics > > on one board. Watch out for noise to couple through the board grounds and many > > other places. > > > > Paul Anderson > > University of Wisconsin > > Computer Sciences Dept. > > Madison, Wis 53706 > > Actually the board layout at 4 Mhz isn't all that critical. It > isn't nearly the problem that noise elimination at 100Mhz presents. > > Mike @ AMDCAD Yes that is true if the part in question is a 4mhz part. When you are using a part that has a 100 mhz analog bandwidth you still have to be carefull with the board layout to reduce ground noise coupling and especially for the stability of the circuit itself. If it oscillates at 100 mhz but you are interested in the last digit of accuracy at 4 mhz what happens? Paul A.