Patent ID: 7960996

Claim:
A variable delay circuit for producing a desired delay time, comprising: a DA converter which supplies a prescribed amount of current based on delay setting data; a delay element which imparts to a prescribed signal a delay amount based on the amount of current; and a bias circuit which is connected between the DA converter and the delay element such that the amount of current flowing in the delay element and the amount of current flowing in the DA converter become equal, wherein the DA converter supplies current which has a hyperbolic relationship with the delay setting data; wherein the DA converter includes a transistor to which a bias voltage corresponding to a variable range of the delay element is applied at its input and a shunt circuit connected to an output of the transistor to divide current flown from the transistor in response to the delay setting data, and wherein the shunt circuit is comprised of a plurality of parallel circuits commonly connected to the output of the transistor, where each parallel circuit consists of a switch and a current source where the delay setting data is supplied to the corresponding switch.