PLL CIRCUIT AND IC CHIP

摘要

PROBLEM TO BE SOLVED: To increase a transfer rate of communication without increasing the frequency of an oscillator provided to a contactless IC chip.

SOLUTION: A value ϕ is varied in accordance with an external control signal and an oscillation output signal represented as cosϕ and an oscillation output signal represented as sinϕ are output from a variable oscillator 71. The signals output from the variable oscillator 71 are multiplied, added and so on, and a signal sin(ωt+ϕt) and a signal cos(ωt+ϕ) which is π/2 out of phase with the signal are output. Based upon the outputs, a phase difference from a current clock signal etc., is determined and a control signal corresponding to the phase difference is supplied to the variable oscillator 71. The present invention is applicable to a PLL mounted on the noncontact IC chip.

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