Compensated impedance calibration circuit

摘要

Aspects of the invention provide for compensating impedance calibration circuits. In one embodiment, a compensated impedance calibration circuit, includes: a variable resistor network including a tunable resistor and a fixed resistor; and an external resistance network including a target external precision resistor and a parasitic distribution resistance; wherein a resistance of the variable resistor network is proportional to a resistance of the external resistance network, such that a ratio of an output voltage of the variable resistor network to a power supply voltage is constant.

主权项

1. A compensated impedance calibration circuit, comprising:
a variable resistor network including a tunable resistor and a fixed resistor; and an external resistance network including a target external precision resistor and a parasitic distribution resistance, wherein a resistance of the variable resistor network is proportional to a resistance of the external resistance network, such that a ratio of an output voltage of the variable resistor network to a power supply voltage is constant, wherein a value for the fixed resistor is selected from a range of discrete values, the range of discrete values including:
a minimum value represented by (Rext(tgt)+Rdistmin)−Rtuned; anda maximum value represented by (Rext(tgt)+Rdistmax)−Rtuned,wherein Rext(tgt) is a resistance value of the target external precision resistor, Rdistmin is a minimum resistance value of the parasitic distribution resistance, Rdistmax is a maximum resistance value of the parasitic distribution resistance, and Rtuned is a resistance value of the tunable resistor.