Four-quadrant active output. What is it? - Page 1
Forum section: electronics / beginners

author: Rostislav
author_rank: Contributor
timestamp: June 08, 2016, 02:07:19 pm
content: Hi, all!My friends, please, tell me, what is this "four-quadrant active output stage" in high voltage amplifier PZD350A?http://www.trekinc.com/products/PZD350A.aspWhich is topology and circuit?Very thanks!!!

author: tszaboo
author_rank: Super Contributor
timestamp: June 08, 2016, 02:23:11 pm
content: Source or sink current, positive or negative voltage output.It is an amplifier, powered by dual rail.

author: Rostislav
author_rank: Contributor
timestamp: June 08, 2016, 02:35:27 pm
content: Quote from: NANDBlog on June 08, 2016, 02:23:11 pmNANDBlog, very thanks!!!Ok!Can whether the classical scheme amplifier (AB class) to replace the four-quadrant topology? Please, see my image. Or no? Maybe other principle work?

author: Rostislav
author_rank: Contributor
timestamp: June 08, 2016, 02:41:58 pm
content: Quote from: NANDBlog on June 08, 2016, 02:23:11 pmNANDBlog,"Dual rail" - bridge circuit (like on a picture)?

author: Rostislav
author_rank: Contributor
timestamp: June 08, 2016, 02:46:41 pm
content: Quote from: NANDBlog on June 08, 2016, 02:23:11 pmNANDBlog,do you have example (schematic) four-quadrant output stage?Very thanks!

author: tszaboo
author_rank: Super Contributor
timestamp: June 08, 2016, 04:20:15 pm
content: Quote from: Rostislav on June 08, 2016, 02:41:58 pmNo, dual rail means that it has an internal positive and negative power supply.It could be a bridged circuit also, like the one you draw, becuase it can output negative voltage on the output therminals. Well, I mean the voltage between the two terminals can change polarity.

author: macboy
author_rank: Super Contributor
timestamp: June 08, 2016, 04:34:46 pm
content: Quote from: Rostislav on June 08, 2016, 02:35:27 pmYes, an audio power amplifier (or any op-amp) is an example of a four quadrant output device.

author: bson
author_rank: Unknown
timestamp: June 10, 2016, 07:53:26 am
content: Quote from: Rostislav on June 08, 2016, 02:07:19 pmIt means it can sink current during the positive phase - for example when faced with a reactive load that lags - and similarly source current during the negative phase. It's a fancy way of saying "negative feedback amplifier".

author: TimFox
author_rank: Super Contributor
timestamp: June 10, 2016, 04:07:55 pm
content: The "quadrants" in question are the four quadrants of a graph of output voltage vs. output current.

author: woodchips
author_rank: Frequent Contributor
timestamp: June 10, 2016, 07:28:14 pm
content: Yes, the first quadrant is +V and +I so the output will source a current flowing out to a +ve voltage. Similarly the third quadrant is -V and -I so the output will source a current flowing out to a -ve voltage.The other two quadrants are the tricky ones.Quadrant 2 is +V and -I, so the output has to sink current flowing into the output from a +ve voltage.Similarly quadrant 4 is -V and +I, so the output has to sink a current flowing into the output from a -ve voltage.What you need is a push pull transistor pair connected between 0V and +ve power rail and the same from 0V to the -ve power rail, with the emitters all joined together. It isn't as simple as just an op-amp output, probably need steering diodes to stop transistors turning on when they shouldn't.Think of it as a supply of +ve voltage, if the output voltage is lower than what is desired then source current. BUT if the output voltage is HIGHER than the desired voltage then it has to sink it. Similar argument for -ve voltage.

author: kridri
author_rank: Contributor
timestamp: June 13, 2016, 02:34:44 pm
content: Quote from: Rostislav on June 08, 2016, 02:46:41 pmThe HP 6826A is an older bipolar/ four quadrant power supply from which you can have the schematics with detailed description. Other know four quadrant supplies are from Keithley but to my knowledge the schematics aren't for download.http://literature.cdn.keysight.com/litweb/pdf/05950-1702.pdf?id=1415976

author: ivaylo
author_rank: Frequent Contributor
timestamp: June 14, 2016, 06:30:32 am
content: Yes, the Keithley or Keysight SMUs do it. Also these -http://www.kepcopower.com/bop.htm