Patent ID: 7015735
Filing Date: 2006-03-21
Classification: H03L

Abstract:
1. A semiconductor integrated circuit having a built-in PLL circuit, said PLL circuit including: a voltage controlled oscillator circuit; a phase comparator circuit for comparing an oscillating signal generated by said voltage controlled oscillator circuit with a reference signal in phase to generate a first signal and a second signal in accordance with a difference in phase between the oscillating signal and the reference signal; a charge pump circuit configured to operate in response to the first signal and the second signal generated by said phase comparator circuit; a loop filter having capacitive elements charged and discharged by said charge pump circuits; and a voltage regulator including a bipolar transistor for generating a base-emitter voltage as a reference for a predetermined voltage generated by said voltage regulator, a first resistive element connected in series with said bipolar transistor, a series connection of a second resistive element and a switching element connected in parallel with said first resistive element, and a temperature detector circuit for detecting a temperature to generate an output for controlling said switching element to switch the voltage generated by said voltage regulator in accordance with the detected temperature, wherein said voltage controlled oscillator circuit is configured to operate with the predetermined voltage generated by said voltage regulator.