AD834 is such an excellent multiplier, why do we rarely see people using it? - Page 1
Forum section: electronics / projects

author: daisizhou
author_rank: Super Contributor
timestamp: July 19, 2024, 12:10:54 am
content: Hello everyoneI plan to build a high frequency power measurement device,The general operating frequency is 800K-3Mhz,To measure RMS voltage and power, I looked at a lot of references.I found the AD834 to be a very good multiplier,I plan to use non-inductive resistors to decay and eventually use the AD834 to measure.But few people use it to make power measurement devices,I do not know whyhttps://www.analog.com/en/products/ad834.html

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 19, 2024, 12:13:38 am
content: Cost mostly - you an get some really nice ADC/DAC/DSP for way less than the cost of that part.

author: daisizhou
author_rank: Super Contributor
timestamp: July 19, 2024, 12:26:25 am
content: But can the bandwidth also reach a maximum of 500MHZ?There is also 0.5% accuracy

author: moffy
author_rank: Super Contributor
timestamp: July 19, 2024, 12:41:05 am
content: Quote from: daisizhou on July 19, 2024, 12:26:25 amThat's why it is expensive, making it uncommon, for me about $80 AUD at Mouser.

author: andrewtaylor
author_rank: Contributor
timestamp: July 19, 2024, 04:48:34 am
content: Quote from: daisizhou on July 19, 2024, 12:10:54 amThe high price and it is single source only from AD -- so that's main reasons.Same with e the LT-chips for RMS measurement (10hz..50/100Mhz possible) -obsolete since decade.(btw. if you didn't aware: LT was sold to AD).

author: dzseki
author_rank: Frequent Contributor
timestamp: July 19, 2024, 06:58:55 am
content: If frequency requirements are not very high , you can also consider AD835 (250MHz), which is a touch cheaper, and has already voltage outputs, plus with the added "+Z" input it can do a few more tricks too.

author: daisizhou
author_rank: Super Contributor
timestamp: July 19, 2024, 07:34:34 am
content: Quote from: andrewtaylor on July 19, 2024, 04:48:34 amI remember the LT1088, but unfortunately it has been discontinued.For RMS measurement, I only know that AD834 is the best choice.

author: daisizhou
author_rank: Super Contributor
timestamp: July 19, 2024, 07:39:49 am
content: Quote from: dzseki on July 19, 2024, 06:58:55 amAre AD834 and AD835 interchangeable?I rarely see any enthusiasts using them to make RMS measurement circuits or other DIY works on the Internet.

author: RoGeorge
author_rank: Super Contributor
timestamp: July 19, 2024, 08:05:00 am
content: I've bought once a batch of AD835 from Aliexpress, in 2015. It was $1.48/pcs in batches of 10pcs. and free shipping.At first I was afraid it would be fake chips, though I've DIY a breakout board for one of those AD835, and measure it at low frequency on a breadboard. The chip was indeed a working analog multiplier. To this day, still didn't test them at high frequency.AD835should work up to 250MHz.Source:https://hackaday.io/project/7574-the-devil-is-in-the-details/log/26074-diy-breadboard-friendly-soic-breakout-boardsFrom traceable vendors the cost was many times higher, but I don't recall the official price.

author: daisizhou
author_rank: Super Contributor
timestamp: July 19, 2024, 08:19:23 am
content: Quote from: RoGeorge on July 19, 2024, 08:05:00 amYes.AD834 sop8 package is very cheap, DIP8 may be slightly more expensive。The reason why I chose AD834 is also based on its price. It seems to be very cheap. The purchase quantity can be 1 or 2, which is up to the buyer.

author: RoGeorge
author_rank: Super Contributor
timestamp: July 19, 2024, 08:59:58 am
content: That's about $0.48/pcs for a 500MHz AD834, right?The Analog Devices webpages forAD835andAD834list them as starting from $16.93/pcs respectively $30.56/pcs for 1ku.Don't know what's the catch, but there must be a reason why the Chinese AD834 is more than 60 times cheaper.

author: daisizhou
author_rank: Super Contributor
timestamp: July 19, 2024, 09:03:39 am
content: Quote from: RoGeorge on July 19, 2024, 08:59:58 amYes It may be old, but for amateur players, it's not important as long as the chip function is normal

author: moffy
author_rank: Super Contributor
timestamp: July 19, 2024, 11:49:58 am
content: Quote from: RoGeorge on July 19, 2024, 08:59:58 amCaveat emptor or buyer beware.

author: dzseki
author_rank: Frequent Contributor
timestamp: July 19, 2024, 12:22:46 pm
content: Quote from: daisizhou on July 19, 2024, 07:39:49 amThey are different. AD834 has a complementary current output ("open collector") that is somewhat awkward to work with. On the other hand AD835 has a single conventional voltage output.Also AD834 is a pure multiplier with a transfer function: W=X*YWhile AD835 has an adder input oo, so the transfer function goes like: W=X*Y+ZI've made various projects with AD834 and AD835 as a contrast modulator for high resolution CRT projectors for home theater enthusiasts.I still have a few chips and boards laying around.

author: Postal2
author_rank: Frequent Contributor
timestamp: July 19, 2024, 12:38:16 pm
content: This chip (or similar) can be used to build a sound converter to speak with the voice of a clown.