Active current bias network for compensating hot-carrier injection induced bias drift

An active bias current network, comprising:

• a target transistor having a bias current;
• reference means to simulate said bias current;
• current sensing means to monitor said bias current, said current sensing means comprising:
• a first current mirror having two transistors biased in the triode region;
• a second current mirror having two transistors biased in the saturation region;
• and
• constant current means to provide a constant current source;
• and
• feedback means to adjust a bias of said target transistor and said reference transistor, said current sensing means is coupled to said reference means, said constant current means is connected to said current sensing means and said feedback means, wherein said feedback means is a transistor coupled to said reference means and said target transistor to form a third current mirror.

A method for regulating the bias current in a transistor, comprising the steps of:

• replicating a bias current from a target transistor with a reference transistor;
• biasing a first current mirror into a triode region;
• sensing said bias current with said first current mirror;
• comparing said bias current to a reference current;
• determining a current difference between said bias current and said reference current;
• adjusting a bias across said target transistor and said reference transistor using said current difference between said bias current and said reference current;
• equalizing the input and output currents of said first current mirror;
• and
• buffering the output of said first current mirror from said reference current with a second current mirror.

An active bias current network for stabilizing the bias current in a target transistor, comprising:

• a reference transistor;
• a first current mirror coupled to said reference transistor, said first current mirror comprising:
• a transistor pair biased in a triode region;
• an operational amplifier having a pair coupled between said transistor pair;
• and
• a biasing transistor connected to an output of said operational amplifier;
• a second current mirror coupled to said biasing transistor, said second current mirror comprised of a transistor pair biased in a saturation mode;
• a reference current source coupled to said second current mirror;
• and
• a feedback transistor coupled between said reference current, said second current mirror, and said reference transistor and said target transistor.

A method of regulating the bias current in a transistor, comprising the steps of:

• producing a bias reference current;
• varying said bias reference current with hot carrier injection;
• monitoring said bias reference current with a current sensor;
• comparing said bias reference current to a constant reference current;
• determining a current difference between said bias reference current and said constant reference current;
• and
• adjusting a bias on said transistor using said current difference.