I have seen leaky integrator circuit using a capacitor and resistor in parallel between inverting terminal and the output of an op-amp. But I was wondering if it is possible to make a leaky integrator using switched capacitance integrator.
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2 Answers
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Here's a simple method:
Add a capacitor, \$C_{leak}\$, to your circuit. One terminal is always grounded. The other terminal is connected either to the op-amp's output or to its inverting terminal, alternating between the two at the switching frequency \$f_S\$. This capacitor acts like a resistor of value \$R_{eq}=1/(f_SC_{leak})\$ between the op-amp's output and its inverting terminal.
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A "leaky integrator" is nothing else than an inverting 1st-order lowpass. If you want to design such a circuit in S/C technique you must replace both resistors (between signal input and inv. opamp input as well as in the feedback path in parallel to the fixed capacitor) by a switched capacitor. As a result, you have two switched capacitors and one fixed capacitor.
