can include a current source and a capacitor in the architecture shown a first branch includes the current source 104 a and the capacitor c 1 a second branch includes the current source 104 b and the capacitor c 2 and a third branch includes the current source 104 c and capacitor c 3 the architecture 100 can have two or more parallel branches where at least two branches can be configured through switches to provide a continuous voltage output in each branch switches are operable to connect and disconnect the current source to the capacitor and to short the capacitor to ground to remove charge on the capacitor the current sources 104 a 104 c can be selected to be closely matched in some implementations an integrator can be used as a source or capacitors and large resistors as pull up sources rather than current sources 104 a 104 c the state machine 108 can be implemented using a programmable logic device a programmable logic controller logic gates and flip flops or relays in some implementations a register can store state variables a first block of combinational logic can determine the state transition and a second block of combinational logic can determine the output of the state machine 108 the state machine 108 together with the digital counter 110 can be used to close and open the switches s 1 s 12 to affect various stages of circuit operation as described in reference to fig2 7 the digital counter 110 can be implemented using register type circuits such as a flip flop e g up down counter or any other known digital counter design switches s 1 s 12 can be semiconductor switches e g mosfet transistors the control inputs to the switches s 1 s.