VCO WITH LINEAR GAIN OVER A VERY WIDE TUNING RANGE

摘要

An oscillating circuit with linear gain is presented. The oscillating circuit may include a relaxation oscillator and a current compensation block. The relaxation oscillator includes a capacitor, a pair of resistors operative to deliver a first current to the capacitor, and a first current source adapted to generate the first current having a first predefined level. The current compensation block includes a second current source, and a pair of cross-coupled transistors coupled to the second current source and adapted to steer a current exceeding the first predefined level in the relaxation oscillator away from the capacitor and to the second current source. The proposed oscillating circuit generates an output signal which has a linear gain over a wide tuning range.

主权项

1. An oscillating circuit, comprising:
a relaxation oscillator comprising:
a capacitor;a pair of resistors operative to deliver a first current to the capacitor; anda first current source adapted to generate the first current having a first predefined level; and a current compensation block comprising:
a second current source; anda first pair of cross-coupled transistors coupled to the second current source and adapted to steer a current exceeding the first predefined level in the relaxation oscillator away from the capacitor and to the second current source.