Discrete time filter network
A discrete time filter network with an input signal connection and an output signal connection and comprising a capacitor bank with a plurality of history capacitors, and at least one sampling capacitor which operates at a predetermined cycling rate to couple to at least one history capacitor at a time, which history capacitor is selected from the capacitor bank so as to share electrical charge between such selected history capacitor and the sampling capacitor, wherein there is a plurality of sampling capacitors that are provided in the capacitor bank, and the discrete time filter network is provided with at least one switch network comprising a plurality of clock driven switches for making selected cyclical connections between the sampling capacitors and the history capacitors in the capacitor bank at the predetermined cycling rate.
1. A discrete time filter network with an input connection and an output connection comprising:
a plurality of N history capacitors CHi (i=1−N), wherein N≥3, and wherein one of the plurality of history capacitors CHi is connected to the input connection and another one of the plurality of history capacitors CHi is connected to the output connection,
at least one sampling capacitor CS which is coupled either parallel or antiparallel to one of the plurality of history capacitors CHi at a time to share electrical charge with positive and negative sign respectively, wherein the antiparallel connection provides a negative feedback path, and
a switch network comprising a plurality of clock driven switches for making a predetermined sequential cyclical connection between the at least one sampling capacitor CS and the history capacitors CHi (i=1−N) at a predetermined cycling rate;
characterized in that
the discrete time filter network comprises a predefined number M of feedback paths, wherein M≥1, the location of which is identified with a predefined list L of M feedback location numbers wherein each location number Lj (j=1−M) ranges from 2 to N and defines the feedback path of the history capacitor Chi to the input, wherein i ranges from i=1 to Lj, and is associated with a sub-cycle j within the predetermined cycling rate, and that
in each sub-cycle j (j=1−M), the at least one sampling capacitor CS is connected sequentially parallel to each history capacitor CHi wherein i ranges from i=1 to Lj, and that upon reaching and connecting to a history capacitor CHi, wherein i=Lj, the at least one sampling capacitor CS is subsequently flipped and connected back antiparallel so as to provide its charge with inverted polarity to the history capacitor CHi, wherein i=1.
2. The filter network of claim 1 , characterized in that a current is provided to the input connection.
3. The filter network of claim 1 , characterized in that a charge is provided to the input connection.
4. The filter network according to claim 1 , characterized in that a plurality of sampling capacitors are sequentially, i.e. with mutual phase-delay, connected to the history capacitors.
5. The filter network of claim 1 , characterized in that the network is embodied without active components.
6. The filter network of claim 1 , characterized in that at least one of the numbers in said list L of M feedback location numbers pertaining to the history capacitors CHi is equal to the number N of history capacitors.