Systems, methods and circuits for implementing a self test in a slowly varying sensor. In one particular case, a circuit is provided that includes two filters operating in parallel. One of the filters is tailored for filtering normal operational signals, and operates at a first oversampling rate. The other filter is tailored for filtering test signals, and operates at a second oversampling rate. The second oversampling rate is generally less than the first oversampling rate. In various cases, the filter tailored for filtering normal operational signals may be programmed for operation across a plurality of oversampling rates.
