Semiconductor integrated circuit

Abstract

The present invention provides a semiconductor integrated circuit capable of reducing a chip occupied area and reducing variations in control gain of a digitally controlled oscillator (DCO). The semiconductor integrated circuit is equipped with the digitally controlled oscillator (DCO). The digitally controlled oscillator (DCO) comprises oscillation transistors (NM1, NM2) and a resonant circuit (20). The resonant circuit (20) comprises inductances (L11, L12), a frequency coarse-tuning variable capacitor array (CCT11) and a frequency fine-tuning variable capacitor array (CFT11). The frequency coarse-tuning variable capacitor array (CCT11) comprises a plurality of coarse-tuning capacitor unit cells (CCT0, CCT1...). The frequency fine-tuning variable capacitor array (CFT11) comprises a plurality of fine-tuning capacitor unit cells (CFT0, CFT1...). The capacitance values of the coarse-tuning capacitor unit cells of the frequency coarse-tuning variable capacitor array (CCT11) are set in accordance with a binary weight 2M-1. The capacitance values of the fine-tuning capacitor unit cells of the frequency fine-tuning variable capacitor array (CFT11) are also set in accordance with a binaryweight 2N-1.

Description

technical field [0001] The present invention relates to a semiconductor integrated circuit with a digitally controlled oscillator (DCO), in particular to a method for reducing the control gain K of a digitally controlled oscillator (DCO). DCO Deviations from beneficial techniques. Background technique [0002] An oscillator capable of variably controlling an oscillation frequency is an essential circuit in information equipment such as wireless communication devices and storage devices. With the development of information equipment, the miniaturization of semiconductor integrated circuits (ICs) for communication is required. Especially in ICs for wireless communication used in mobile phones and wireless LANs (Local Area Networks, local area networks), the processing of radio frequency in IC chips The necessity of monolithically integrating an RF circuit for a (RF: Radio Frequency) signal and a BB circuit for processing a baseband (BB: Base Band) signal is increasing. [00...

AI Technical Summary

Problems solved by technology

However, in the DEM method, each variable capacitance constituting the tracking group needs to be individually controlled

Therefore, when the DEM method is applied to a tracking group including 2000, 4000, etc. a large number of variable capacitors, not only 2000, 4000 control lines are required, but also a control logic circuit for controlling each capacitor is required separately, so the inventor proposes solves the problem of larger chip footprint

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