Digital microphones

A digital microphone apparatus for outputting a digital output signal at a sample rate defined by a received clock signal received by the digital microphone apparatus, the apparatus comprising:

• a band splitter configured to receive a microphone signal indicative of an output of a microphone transducer and split said microphone signal into first signal path for frequencies in a first frequency band and a second signal path for frequencies in a second frequency band, the frequencies of the second frequency band being higher than the frequencies in the first frequency band;
• and
• a modulation block configured to down-convert signals in the second frequency band to a third frequency band, wherein the third frequency band extends across a frequency range that is lower than the second frequency band;
• wherein:
• the second signal path comprises a mixer for mixing the signals in the second signal path with an oscillator signal and a band-pass filter downstream of the mixer with a pass-band corresponding to the third frequency band;
• and
• the modulation block comprises an oscillator for generating the oscillation signal wherein the oscillator is configured such that the frequency of the oscillation signal is variable.