Threshold voltage control network for integrated circuit field-effect trransistors

Claim 1

A threshold voltage control circuit for controlling threshold voltages of selected field-effect transistors formed as part of an integrated circuit and having respective drains, sources and gates thereof electrically interconnected in said integrated circuit in any desired manner including a first field-effect transistor, said threshold voltage control circuit comprising: a reference field-effect transistor formed as part of said integrated circuit having a drain, a source and a first gate with said first gate and source electrically connected together, with said reference field-effect transistor being electrically connected to said first field-effect transistor such that said reference field-effect transistor has a threshold voltage which determines that threshold voltage associated with said first field-effect transistor, said reference field-effect transistor drain being electrically connected to a first terminal means characterized as being connectible to a first voltage source; an impedance means electrically connected to a second terminal means characterized as being connectible to a second voltage source and electrically connected to said reference field-effect transistor source wherein said impedance means has a first or a second impedance value depending on values of a control signal; and means for providing threshold voltage control to said reference field-effect transistor depending on impedance values taken by said impedance means to cause said threshold voltage of said reference field-effect transistor to attain a value which maintains current flowing between source and drain of said reference field-effect transistor substantially equal to that flowing through said impedance means, said threshold voltage of said reference field-effect transistor having a first value when said impedance means has said first impedance value and having a second value when said impedance means has said second impedance value.