Write head fault detection with small threshold
AssigneeTexas Instruments Incorporated
InventorsHong Jiang, James Nodar
Life of this patent
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Abstract
A circuit (50) and method are provided for generating a signal (84) indicating an open impedance fault of a coil (56) of a write head (18) of a mass data storage device (10). The circuit (10) includes a differential amplifier (51) with the electrical component (56) being connected as a load in a first leg thereof. An impedance element (64) is provided in a second leg of the differential amplifier (50), and a pair of bipolar transistors (52,54) are respectively connected in the first and second legs. The pair of bipolar transistors (52,54) have a constant bias voltage (Bias) applied to inputs thereof, and an output circuit is connected to an output node of the first leg of the differential amplifier (51).
Claims26
A circuit for generating a signal indicating an impedance fault of an electrical component comprising:
- a differential amplifier;
- said electrical component being connected as a load in a first leg of said differential amplifier;
- an impedance element in a second leg of said differential amplifier;
- a pair of bipolar transistors respectively connected in said first and second legs of said differential amplifier;
- said pair of bipolar transistors each having a same constant bias voltage applied to inputs thereof;
- and an output circuit connected to an output node of said first leg of said differential amplifier.
A circuit for generating a signal indicating an impedance fault of an electrical component, comprising:
- a differential amplifier;
- said electrical component being connected as a load in a first leg of said differential amplifier;
- an impedance element in a second leg of said differential amplifier;
- a pair of bipolar transistors respectively connected in said first and second legs of said differential amplifier;
- said pair of bipolar transistors having a constant bias voltage applied to inputs thereof;
- and an output circuit connected to an output node of said first leg of said differential amplifier;
- wherein said output circuit comprises an output transistor connected to said output node, an output inverter having an input connected to receive an output of said output transistor, and a current source to bias said input of said output inverter to a predetermined quiescent voltage value.
A circuit for generating a signal indicating an impedance fault of an electrical component, comprising:
- a circuit for providing differential amplification in first and second differential current legs;
- said electrical component being connected as a load in said first differential current leg;
- a circuit for providing a matching impedance in said second differential current leg;
- an active amplifier in said first and second differential current legs for providing differential amplification of currents in said first and second differential current legs;
- said active amplifier having a constant bias applied to inputs thereof;
- an output circuit connected to an output node of said first differential current leg for providing said signal indicating an impedance fault of said electrical component;
- wherein said output circuit comprises an active output amplifier device connected to said output node for detecting an output voltage at said output node, an output inverter having an input connected to receive an output of said output amplifier device for providing an output signal, and a current source for providing a current to bias said input of said output inverter to a predetermined quiescent voltage value.
A circuit for generating a signal indicating an impedance fault of an electrical component, comprising:
- a circuit for providing differential amplification in first and second differential current legs;
- said electrical component being connected as a load in said first differential current leg;
- a circuit for providing a matching impedance in said second differential current leg;
- active amplifier in said first and second differential current legs for providing differential amplification of currents in said first and second differential current legs;
- said active amplifier having a constant bias applied to inputs thereof;
- an output circuit connected to an output node of said first differential current leg for providing said signal indicating an impedance fault of said electrical component;
- further comprising a set of replicating elements in said first current leg, each replicating element being connected in parallel with a corresponding element of said first current leg.
A method for generating a signal indicating an impedance fault of an electrical component connected as a load in a first current leg, comprising:
- differentially amplifying currents in respective said first current leg and a second current leg with a fixed amplification value;
- providing a matching impedance for said electrical component in said second current leg;
- and providing an output amplifier at an output node of said first current leg for providing said signal indicating an impedance fault of said electrical component;
- wherein said step of providing an output amplifier comprises providing an active output amplifier device connected to said output node for detecting an output voltage at said output node, providing an output inverter having an input connected to receive an output of said active output amplifier device for providing an inverted output signal, and a current source for providing a current to bias said input of said output inverter to a predetermined quiescent voltage value.
Dependencies are inferred from the claim text.