Are there are real life examples of using a current mirror?
I am using the following current sensing amplifier chip, which is using a current mirror.
My real life project still in progress is to plot the I-V curve of a tunnel diode. Because the current I am measuring is very small, in the range of uV to a couple of mV, so I need a current sense amplifier to convert the tiny current to 0 ~ 5V, and I also use a 12-bit ADC to read the digital value which will be read and stored by a Raspberry Pi.
The photo below shows my calibration hardware setup.
Wiring the tiny MAX4172 is a bit tricky. There is no assembled module available, so I need to do the point to point wiring, luckily only 8 pins, to a SOC8 to DIP8 breakout board. I have about 100 hours of SMD hand soldering experience, so it took me only 15 minutes to do the first chip, and then 10 minutes in average for the later ones. The photo below shows my craftmanship. :)
The software part is not that difficult. I skimmed the datasheet, and found that there is actually no programming required. I only need to find out the a bit complicated amplification gain factor table, and choose the gain resistor to fit my current range. My datasheet summary is show below.
The picture below shows my working on the current sense and output resister
My quick and dirty conclusion is that the hardware soldering is a bit tricky, but there is no software need, just simple calculation.
So all in all, a damn cheap newbie friendly toy to learn new stuff.
MAX4172 is an example of using current mirror at the current sensing amplication application level. Another example of using current mirror at the circuit design level can be found in Refs 6, 7, where current mirror is used in CCS, Constant Current Source
I am making a constant current source, with reference to the Zener based one transistor circuit of the Wikipedia article on "Constant Current Source". The Wiki article points out that a "boost current mirror" is used this circuit. The definition of current mirror by the Wiki article is also very good.
(1) MAX4172 Low-Cost, Precision, High-Side Current-Sense Amplifier Product Sheet - Maxim
(2) MAX4172 Low-Cost, Precision, High-Side Current-Sense Amplifier Datasheet -Maxim
(3) Maxim MAX4172ESA High Side Current Sense Amplifier - TaoBao ¥1.25
(4) SOP8 SMD to DIP8 Breakout Board - TaoBao, ¥2/10pcs
(5) Current Mirror - Wikipedia
(6) The Basic MOSFET Constant-Current Source June 06, 2016 by Robert Keim - aac
(7) Current Mirror BJTs - aac