Current generator, notably for current of the order of nano-amperes, and voltage regulator using such a generator

A current generator using field-effect transistors, comprising:

• a first plurality of Q transistors connected as a current mirror and able to be linked to a supply voltage, each of the first plurality of transistors having a channel of a first polarity;
• a second plurality of Q−1 transistors connected as a current mirror, each having a channel of a second polarity that is the reverse of the first polarity, and each connected in series to a transistor included in the first plurality of transistors;
• a first transistor N3R having a channel of the second polarity, having an equivalent resistance Req, and connected in series with a transistor included in the second plurality of transistors;
• and
• a second transistor N4, connected as a current mirror with the first transistor N3R, and connected in series with a transistor included in the first plurality of transistors;
• wherein
• the first transistor N3R is able to operate in its linear zone;
• an amount of current generated by the current generator is dependent on the equivalent resistance Req of the first transistor N3R;
• the first and second transistors N3R, N4 each have an ultra-long channel, each ultra-long channel having a ratio L/W greater than several hundred, L being the length of the ultra-long channel and W its width, the values of W and of L/W being determined so as to obtain a stable value of current as a function of a variation of the supply voltage.