The University of New Mexico

Science & Technology Corporation

David F Cox

Method and apparatus for controlling amplifier output offset using body biasing in MOS transistors. A pair of input transistors have isolated bodies. A differential input signal is applied across the gates of the input transistors. An output signal is derived from a voltage at the drain of one of the input transistors. A feedback loop includes an integrator and a feedback amplifier. The integrator integrates the output signal, thereby forming an integrated output signal. The integrated output signal is applied to a first input of the feedback amplifier, while a reference voltage is applied to a second input of the feedback amplifier. The feedback amplifier controls the voltage of the body of one of the input transistors. The body of the other input transistor is coupled to its source. The threshold voltage of the input transistor having its body coupled to the feedback amplifier is controlled such that a quiescent level of the output signal tends to equal the reference voltage. A time constant associated with the feedback loop is sufficiently long that frequencies of interest for the input differential signal pass to the output of the amplifier without affecting the bias voltage formed by the feedback loop. A comparator differs from the amplifier in that the integrator and feedback amplifier are omitted and, instead, a second reference voltage is applied directly to the body of the input transistor having its body voltage controlled. The offset voltage is reduced or eliminated by adjusting the second reference voltage.

Apparatus for and method of controlling amplifier output offset using body biasing in MOS transistors

The system converts output signals from the conventional circuit into input signals configured for the ULP circuit. This system preferably scales down the output signals from the conventional circuit to allow the ULP circuit to receive these signals as corresponding input signals without damaging the ULP circuit. Further, the system also converts output signals from the ULP circuit into input signals configured for the conventional circuit. This system preferably increases the voltage level and voltage swing of the output signals from the ULP circuit to be compatible as corresponding input signals for the conventional circuit. The system is a circuit formed in a semiconductor substrate having improved immunity to total ionizing dose radiation. By back-biasing the n-type material and the p-type material, the effective threshold voltages of the transistors both drawn and parasitic are preferably dynamically tuned. Preferably, by optimizing the threshold voltages of the n-channel and p-channel transistors, the total ionizing dose radiation effect is neutralized and lower supply voltages are utilized for the circuit which would result in the circuit requiring less power.

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Los Lunas, NM, United States of America

David F Cox