Patent Document ID: 20130321031
Application ID: 13482875
Patent Flag: 0

Claim One:
1. A CMOS programmable non-linear function synthesizer, comprising: a plurality of current squarer circuits having a plurality of MOSFET transistors configured for providing current gain and current mirroring, each of the squarer circuits including a bias circuit controlling the current gain responsive to an external voltage, the current gain responsiveness to the external voltage being characterized by the relation: I out = k 1 k 3 2 ( V GG - V th ) 2 I in 2 , where V GG is a gate voltage operable within the bias circuit, I in is the input current of the current squarer circuit, k 1 is a transconductance parameter of the current gain portion of the current squarer circuit, k 3 is a transconductance parameter of the bias circuit, and V th is a threshold voltage associated with the formation of the gate voltage, the bias circuit having MOSFET transistors operating in a linear region, the current gain portion of the current squarer circuit having MOSFET transistors operating in a saturation region, the current gain representing at least one term of a Taylor series expansion of a nonlinear function; successive power-factor raising circuit stages, each of the stages being connected to the current squarer circuits, the successive power-factor raising circuit stages including combinations of inverting and non-inverting current mirrors, the power-factor raising stages each producing a current output; a variable DC current source; a summer circuit having a plurality of switches configured to combine currents from the variable DC current source and the plurality of power-factor raising current stages, each of the switches having a first position configured to switch the current for the DC current source or the corresponding power-factor raising stage to a positive current, a second position configured to the current for the DC current source or the corresponding power-factor raising stage to a negative current, and a third position configured to disconnect the current for the DC current source or the corresponding power-factor raising stage from the summer circuit, the switch positions representing sign coefficient weights applied to successive terms of the Taylor series expansion of the nonlinear function of interest; wherein the total current output of the summer circuit approximates the nonlinear function, the squarer circuits, the power-factor raising circuit stages, and the switch positions being configured to represent weighted power factors corresponding to the plurality of terms in the Taylor-series expansion of the nonlinear function.