Stable constant-current bias CASCODE MMIC (Multi-Media Integrated Circuit) VCO (Voltage Controlled Oscillator)

Abstract

The invention discloses a stable constant-current bias CASCODE MMIC VCO. The stable constant-current bias CASCODE MMIC VCO comprises a VCO body, a buffer amplifier, a constant-current bias circuit, aholding circuit and an output matching circuit. The VCO is an oscillation frequency selection circuit controlled by external voltage, an oscillation tube of the VCO is connected with the second-stagebuffer amplifier through cascode, and a radio frequency signal of the VCO is subjected to cascade amplification through the buffer amplifier and then reaches a load through the output matching circuit. The constant-current bias circuit is used for providing constant current bias for the VCO, and the holding circuit is a resistor connected to the base electrode and the collector electrode of the buffer amplifier. When the voltage of the power supply changes, the constant-current source bias and the holding circuit are adopted to keep the quiescent current of the VCO and the quiescent bias pointof the buffer amplifier unchanged. Therefore, the circuit can stably oscillate under different power supply voltages, the oscillation frequency and the amplitude-frequency characteristic in the working bandwidth are kept unchanged, and the circuit has good and stable working performance.

Description

technical field [0001] The invention relates to a CASCODE MMIC VCO (a single-chip microwave integrated voltage-controlled oscillation circuit adopting a cascode amplifier structure), in particular to a stable constant current bias CASCODE MMIC VCO. Background technique [0002] The VCO (Voltage Controlled Oscillator) using the Cascode (cascode amplifier) ​​structure can cascade amplify the radio frequency signal, reduce the load pull effect, and make the VCO have a large output power and good output isolation. It is widely used in In the design of MMIC (Monolithic Microwave Integrated Circuit) VCO. [0003] The traditional Cascode VCO is usually biased by resistor divider. Take BJT / HBT as an example, figure 1 It is an implementation of the traditional Cascode VCO circuit. Transistors Q1 and Q2 adopt cascode cascade connection, and VCC passes through resistor R b1 , R b2 and R b3 Voltage biases the circuit. [0004] Assuming that the transistor works in the enlarged re...

AI Technical Summary

Problems solved by technology

Since in practical applications, the working voltage of VCO is usually uncertain and changes within a certain range, so this problem will lead to deterioration of VCO performance indicators, or even stop working

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