Analog tunneling current sensors for use with disk drive storage devices

摘要

Amplifier architectures are provided for current sensing applications. An amplifier includes a load device, an operational amplifier, a current source, and a bipolar transistor. The operational amplifier has a first input terminal connected to a first input node that receives an input current, and a second input terminal connected to a second input node that receives a reference voltage. The current source is connected to an output of the operational amplifier. The operational amplifier, the current source, and the bipolar transistor form a feedback loop that generates and maintains a bias voltage on the first input node based on the reference voltage applied to the second input node. The bipolar transistor amplifies the input current received on the first input node, and generates an amplified input current. The load device converts the amplified input current to an output voltage, wherein the output voltage is used to sense the input current.

主权项

1. An amplifier circuit, comprising:
a first node configured to receive a first current; a second node configured to receive a reference voltage; feedback circuitry configured to form a feedback loop that generates and maintains a bias voltage on the first node based on the reference voltage at the second node, wherein the feedback circuitry comprises a bipolar transistor having a base terminal connected to the first node, and wherein the bipolar transistor is configured to amplify the first current so as to provide a second current; a reference circuit configured to generate a scaled version of the second current; and a comparing circuit configured to compare an output voltage with an output reference voltage to detect when the first current is at a predetermined level, wherein the output voltage is generated based on the second current, and wherein the output reference voltage is generated based on the scaled version of the second current.