simple 150uA constant current supply

I would like to find the simplest way to provide a constant current of
around 150uA (+/-20%) at around 2V.
This needs to be discrete components rather than IC and should not involve
pulse width modulation.
The simplest form I thought of was a 3v voltage reg with a 20K resistor
between it's 'reference ground' and the output but this seems clumsy.
Anyone ?
Thanks
Dave


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