Switched-current biquad using differential, double-sampling, forward/backward difference integrators

A new switched-current integrator which accomplishes forward and backward difference integration and achieves double-sampling capabilities is described. The signal-flow graphs (SFGs) of several double-sampling integrators are derived and mapped into transistor circuits. Furthermore, as an example, a biquad based on an exact design and operating in differential and double-sampling mode is described and simulated. It is shown that the pole sensitivity of this biquad is reduced by a factor of 2 and the coefficient spread by a factor of 3 when compared with a bilinearly transformed reference filter