Patent ID: 7161412

Claim:
A calibration circuit for a current source cell, the current source cell including a current source providing a first current to a current output node, the current source having a calibration voltage node for receiving a bias voltage that drives the current source to provide the first current having a substantially constant value, the calibration circuit comprising: a reference current source supplying a reference current to a first node, the first node being switchably connected to the current output node; and a transresistance amplifier having an input terminal coupled to the first node for receiving an input current and an output terminal switchably connected to the calibration voltage node, the output terminal providing an output voltage indicative of the input current, wherein when the first node is connected to the current output node and the output terminal of the transresistance amplifier is connected to the calibration voltage node, the input current develops at the first node having a value equal to the difference between the first current and the reference current, the transresistance amplifier receives the input current and generates the output voltage in response to the input current for driving the calibration voltage node, the output voltage having a value operative to nullify the difference between the first current and the reference current, thereby calibrating the current source cell.