Low-noise voltage-controlled oscillator biasing circuit and frequency source self-calibration method

Abstract

The invention discloses a low-noise voltage-controlled oscillator biasing circuit and a frequency source self-calibration method. A voltage division circuit comprises a resistor R1, a first bipolar junction transistor BJT1 and a second bipolar junction transistor BJT2 which are connected in series in sequence, wherein the R1 is connected with the collector of the BJT1; the emitter of the BJT1 is connected with the collector of the BJT2; the collector of the BJT1 is connected with the base of the BJT1; and the collector of the BJT2 is connected with the base of the BJT2. In a self-calibration state, voltage output by the biasing circuit is connected with the tuning voltage input end and the power supply end of an LC voltage-controlled oscillator respectively. The output noise of the biasing circuit disclosed by the invention is low, a filter capacitor does not need to be added externally, the pins of a chip can be effectively reduced, and the cost is reduced; and when a frequency source is in the self-calibration state, the voltage output by the biasing circuit is connected with the tuning voltage input end and the power supply end of the LC voltage-controlled oscillator respectively, so that influences caused by the change of an output DC (Direct-Current) point due to changes of the resistor and the BJTs in a whole temperature range can be effectively eliminated, and change of the frequency source along with temperature change in the self-calibration state is avoided.

Description

technical field [0001] The invention relates to a low-noise voltage-controlled oscillator bias circuit and a frequency source calibration method. Background technique [0002] At present, the frequency source circuit uses an LC voltage-controlled oscillator, and its structure is as follows figure 1 As shown, it is mainly composed of negative resistance, inductance and capacitance, and its output power is: Among them, L is an inductor, C is a capacitor, and the capacitor C is composed of three parts: a parasitic capacitor, a variable capacitor, and a programmable capacitor array. The function of capacitor C2 and capacitor C3 is to block the direct current, and give the LC voltage-controlled oscillator a DC point through other bias circuits, so that the capacitance value of the variable capacitor follows the voltage at both ends of the LC voltage-controlled oscillator (power supply terminal DC and tuning The change of the voltage difference at the voltage input terminal Vtu...

AI Technical Summary

Problems solved by technology

[0003] like image 3 As shown, the traditional bias circuit generally divides the voltage by resistors, but because the noise of the voltage divider circuit composed of series resistors R4 and R5 is relatively large, it is necessary to add a large capacitor outside the bias circuit ( image 3 Capacitor C4) in the filter, which increases the output pin of the bias circuit and increases the circuit cost

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