Yes, looking for a current source for some amplifiers.

@User I've just committed the DRC/LVS clean beta-multiplier here: https://github.com/yrrapt/amsat_txrx_ic/tree/master/design/bandgap_bmr Hopefully it's useful for you

I'll take a look...I'm not too familiar with beta-multiplier design...if I need to adjust current do I need to resize all the transistors? or is there a relatively easy way to adjust this

@Trevor Clarke The output is a voltage which can be connected to the gate of a matching PMOS to gate the current. You can increase the multiplicity of the PMOS to get more current

so I can generate multiple biases adding that number of PMOS with appropriate sizing?

Yeah, the biasv port can be connected to as many PMOS devices as you want to create multiple currents

@yrrapt ok, finally getting around to testing this, can you take a look and see if I'm using it correctly? https://github.com/tclarke/sky130radio/basic there's SVGs of the schematics in doc. Haven't properly sized the transistors yet.

@Trevor Clarke the use of the BMR looks good. The circuit below probably won't do what you want because M2 is Biased off but that's a different issue

yea, I haven't biased or sized anything, just a quick layout to make sure I was understanding you properly. Sounds like I am. Do you have a handy copy of the equation to size the V2I pfet for a specific current? I can look it up but figured you might know offhand. (changing M won't be accurate enough for my needs)

In theory it's the ratio of W/L between the reference FET in the BMR and the output one. But in practise you're edge effects etc. means that doesn't hold that well unless you're copying unit components that match exactly. It's worth bearing in mind the current is derived from a resistor with about +/- 20% tolerance and then there's probably about +/- 10% temperature variation with this circuit too so it may not be worth working too hard to dial in exact current values that you can only get in the simulation with tt corner at 27 degC

🤔 got it