High frequency common mode rejection technique for large dynamic common mode signals
AssigneeDialog Semiconductor (UK) Limited
InventorsZakaria Mengad, Vladislav Vasilev, Steven Collins
Life of this patent
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Abstract
A system is disclosed which allows for canceling high frequency rail to rail common mode swing at pulse-width modulation (PWM) frequency for a Class-D, H and G audio amplifier or a Linear Resonance Actuator (LRA) driver. This allows wide bandwidth current sensing without the need of external components, or large on-chip resistor-capacitor (RC) networks, facilitating integration of the sense resistor. In addition, the sense amplifier DC input common mode and audio band common mode swing is reduced, allowing a sense resistor high frequency common mode swing of a least twice the MOSFET gate break down voltages.
Claims19
A high frequency common mode rejection circuit for large dynamic common mode signals, comprising:
- a sense resistor, configured in series with a load;
- a summing amplifier configured to sense current through said sense resistor, an output of said summing amplifier comprising said common mode signals;
- a low pass filter between said sense resistor and said summing amplifier;
- and
- a high voltage (HV) inverter, having a supply voltage of 8 or more volts, having its input connected to said sense resistor on a side of said sense resistor opposite to said load and having its output connected to said low pass filter.
A method for high frequency common mode rejection for large dynamic common mode signals, comprising the steps of:
- providing a sense resistor, configured in series with a load;
- providing a high voltage (HV) inverter, having a supply voltage of 8 of more volts, having an input of said high voltage inverter connected to said sense resistor on a side of said sense resistor opposite to said load;
- sensing current through said sense resistor, configured to a summing amplifier, an output of said summing amplifier comprising said common mode signals;
- and
- providing a low pass filter between said sense resistor and said summing amplifier
- cancelling said common mode signals, allowing a high frequency common mode swing on said summing amplifier.
Dependencies are inferred from the claim text.