Reconfigurable filter network with shortened settling time
AssigneeInfineon Technologies AG
InventorsVictor Popescu-Stroe, Dan-Alexandru Mocanu
Life of this patent
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Abstract
A filter circuit includes a first stage comprising a first infinite impulse response (IIR) filter; a third stage comprising a third IIR filter; and a second stage interposed between the first stage and the third stage, the second stage comprising a second IIR filter, where an output terminal of the first IIR filter is coupled to an input terminal of the second IIR filter, and an output terminal of the second IIR filter is coupled to an input terminal of the third IIR filter, where the second stage of the filter circuit is configured to operate in an acquisition mode when a transient is detected in an input signal to the first IIR filter, where during the acquisition mode, the second stage of the filter circuit is bypassed.
Claims21
A filter circuit comprising:
- a first stage comprising a first infinite impulse response (IIR) filter;
- a third stage comprising a third IIR filter;
- a second stage interposed between the first stage and the third stage, the second stage comprising a second IIR filter, wherein an output terminal of the first IIR filter is coupled to an input terminal of the second IIR filter, and an output terminal of the second IIR filter is coupled to an input terminal of the third IIR filter, wherein the second stage of the filter circuit is configured to operate in an acquisition mode when a transient is detected in an input signal to the first IIR filter, wherein during the acquisition mode, the second stage of the filter circuit is bypassed;
- and
- a monitoring circuit coupled to the first stage, the second stage, and the third stage, wherein the monitoring circuit is configured to:
- compute a difference between an output of the third IIR filter and a scaled version of an output of the first IIR filter;
- declare detection of the transient in the input signal to the first IIR filter when the computed difference is larger than a pre-determined threshold;
- and
- in response to the detection of the transient, set the second stage of the filter circuit into the acquisition mode.
A system comprising:
- a microelectromechanical systems (MEMS) sensor;
- a filter network comprising:
- a first infinite impulse response (IIR) filter, an input terminal of the first IIR filter coupled to an output terminal of the MEMS sensor;
- a third IIR filter, an output terminal of the third IIR filter coupled to an output terminal of the filter network;
- and
- a second IIR filter coupled between the first IIR filter and the third IIR filter, wherein the first IIR filter, the second IIR filter, and the third IIR filter are first-order IIR filters, wherein the second IIR filter is configured to operate in a first mode or a second mode, wherein the filter network has a first convergence speed when the second IIR filter operates in the first mode, and the filter network has a second convergence speed slower than the first convergence speed when the second IIR filter operates in the second mode, wherein in the first mode, for each input sample of the filter network, a register of the second IIR filter is loaded with a value that is a scaled version of an output of the first IIR filter;
- and
- a monitor circuit coupled to the filter network, wherein the monitor circuit is configured to:
- detect a transient in an input signal at the input terminal of the first IIR filter;
- and
- set the second IIR filter to operate in the first mode in response to detecting the transient.
A method of operating a filter network, the filter network comprising a first infinite impulse response (IIR) filter, a second IIR filter, and a third IIR filter coupled in series, with the second IIR filter coupled between the first IIR filter and the third IIR filter, wherein the first IIR filter, the second IIR filter, and the third IIR filter are first-order IIR filters, wherein the method comprises:
- monitoring an input signal and an output signal of the filter network;
- detecting a transient in the input signal of the filter network;
- and
- in response to detecting the transient, operating the second IIR filter in an acquisition mode, wherein operating the second IIR filter in the acquisition mode comprises:
- for each input sample of the filter network, loading a scaled value of an output of the first IIR filter into a register of the second IIR filter.
Dependencies are inferred from the claim text.