Unipolar transistor as current amplifier
I think you are getting your terms mixed up a bit. A Unijunction Transistor is a device that acts a switch and cannot be used as a linear amplifier.

Unijunction Transistor

The term Unipolar Transistor is very rarely used - I have never heard it in 50 years. That is a name for an FET since it only uses majority carriers.

You can easily use an FET as a current amplifier by using a resistor to convert the input current into a voltage then using the FET to amplify that voltage to a current

To get accuracy from a circuit like this one would usually use a differential stage to cancel the threshold voltage and an opamp with a feedback circuit to control the gain. In this example the gain will vary with the gm of the FET and there will be a standing current that depends upon the threshold voltage of the device.







simulate this circuit &ndash; Schematic created using CircuitLab

It is rare however to require an amplifier to output current though - usually the need is to amplify a small voltage (or current) with voltage as the output.