Emitter follower and voltage controlled oscillator using same

Abstract

The invention discloses an emitter follower and a voltage controlled oscillator using the emitter follower. The emitter follower comprises a first heterojunction bipolar transistor, a capacitor and a current source, wherein the base of the first heterojunction bipolar transistor is connected with the output end of the voltage controlled oscillator, the collector of the first heterojunction bipolar transistor is connected with a power supply, and the emitter of the first heterojunction bipolar transistor is the output end of the emitter follower; the capacitor is connected between the base and emitter of the first heterojunction bipolar transistor; and the current inflow end of the current source is connected with the emitter of the first heterojunction bipolar transistor, and the current outflow end of the current source is grounded. According to the invention, by adding the capacitor between the base and the emitter of the heterojunction bipolar transistor, the distortion degree and non-linearity of output wave shape of the emitter follower can be reduced.

Description

Technical field [0001] The invention relates to the field of integrated circuits in the electronics industry, in particular to an emitter follower and a voltage controlled oscillator using the emitter follower. Background technique [0002] The voltage-controlled oscillator (VCO) is a very important functional module in the radio frequency analog integrated circuit. It is used to provide a stable local carrier signal, which has a great impact on the performance of the application system, and achieves high integration, high performance, and low cost. Power consumption and low-cost voltage-controlled oscillators have always been the focus and focus of research. [0003] When designing a voltage-controlled oscillator, determining the circuit topology and selecting the device process type are all key steps. The device process type also has a greater impact on its performance. For example, the low-frequency noise of a transistor has an impact on its phase noise. These low-frequency noi...

AI Technical Summary

Problems solved by technology

If the voltage at point A V A and point B voltage V B The amplitude of the larger, the output of the emitter follower V o1 , V o2 The amplitude is also larger, which in turn makes the transistor Q 3 , Q 5 The change of the collector current is also large, which will introduce high nonlinearity to the emitter follower, cause the emitter follower to generate harmonic distortion, and deteriorate the phase noise performance of the oscillator

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