Amplifier

An amplifier circuit for coupling a voltage source to a load, the load having a frequency domain transfer function g(s), said circuit comprising:

• coupling means having a frequency domain transfer function f(s);
• first connecting means for connecting said coupling means between the source and the load;
• compensating means having a frequency domain transfer function r(s);
• and second connecting means for connecting said compensating means to both the source and the load;
• wherein:
• the voltage source has first and second output terminals and the load has first and second ends;
• said coupling means comprise differential amplifying means having first and second inputs, an output and means for generating a voltage at said output which is proportional to the difference in potential at said first and second inputs, said first input being connected to said first connecting means for connection to the first output terminal of the source, said output being connected to said first connecting means for connection to the first end of the load, and said second input being connected to said output;
• and said compensating means comprise second amplifying means having at least one input, an output and means for establishing a high voltage gain between said input and said output, said output of said second amplifying means being connected to said second connecting means for connection to the second output terminal of the source and to the second end of the load, and said input of said second amplifying means being connected to said output of said second amplifying means by a circuit connection which maintains the potential at said input of said second amplifying means substantially equal to the potential at said output of said second amplifying means.