Systems and methods for processing temperature data or other signals
In an embodiment, a circuit is configured to produce a magnetic field signal having a frequency spectrum. The circuit may also produce a temperature signal. A modulation circuit may modulate the temperature signal with a frequency outside the frequency spectrum of the magnetic field signal. The modulated signal and the magnetic field signal may be combined to produce a combined signal. A separation circuit may be configured to separate component signals from the combined signal. The separation circuit may include a first filter, which, when applied to the combined signal, produces a filtered signal; a modulation circuit configured to shift the data representing the temperature signal to a baseband frequency; and a second filter configured to separate the data representing the temperature signal from the combined signal.
1. A magnetic field sensor comprising:
a circuit configured to produce a magnetic field signal having a frequency spectrum, wherein the magnetic field signal represents a strength of an external magnetic field;
a temperature sensing circuit configured to produce a temperature signal for calibrating the magnetic field signal;
a first modulation circuit configured to modulate the temperature signal to a frequency outside the frequency spectrum of the magnetic field signal, resulting in a first modulated signal;
a combining circuit configured to combine the magnetic field signal with the first modulated signal to produce a combined signal; and
an output operative to provide the combined signal to a digital processing circuit.
2. The magnetic field sensor of claim 1 further comprising a separation circuit configured to separate data representing the temperature signal from the combined signal to produce a temperature reading.
3. The magnetic field sensor of claim 2 wherein the separation circuit comprises one or more of:
a second modulation circuit configured to shift the data representing the temperature signal to a baseband frequency, resulting in a second modulated signal; and
a filter coupled to receive the second modulated signal and configured to separate the data representing the temperature signal from the second modulated signal.
4. The magnetic field sensor of claim 2 wherein the circuit configured to produce the magnetic field signal is a circuit for detecting speed or position of a target object and a width of the frequency spectrum is defined by the speed of the target object.
5. The magnetic field sensor of claim 4 further comprising a magnetic field sensing element, wherein the target object is a wheel having teeth, wherein peaks on the magnetic field signal are produced as the teeth of the wheel move past the magnetic field sensing element.