For simple MOSFET-pair current mirrors, such as the NMOS version above, are there any known disadvantages that one has to consider? The above example, for instance, does not perfectly mirror the current (I really don't know about this, as the LTSpice sim works perfectly).
I'm excluding the discussion about parameter mismatch between the MOSFET pairs (V_TO, λ, K, etc)and the condition I_REF ≤ V1/R_LOAD, but more of noise or bias or anything like that.
What I mean is does this just sorta average out as current mirroring? The same way that a Common Drain sorta averages out as having voltage gain of a little less than unity?
What about frequency response? Can MOSFET-pair Current Mirrors reach GHz range? Or, Is it useless to ask? This being the simplest MOSFET-based Current Mirror?