Numerical control attenuator based on capacitance compensation

Abstract

The invention discloses an attenuator based on capacitance compensation, the attenuator comprises a transistor switch, a parallel attenuation resistor, a parallel open-circuit line capacitor and a matching transmission line, and the attenuator utilizes the switch to switch an attenuation state and a direct connection state so as to realize the control of relative attenuation; the attenuator is simple in structure, small in occupied area and good in parasitic phase modulation and attenuation characteristic bandwidth, and has great advantages and application space in monolithic integrated circuit application.

Description

technical field [0001] The invention relates to the field of attenuators, more specifically, it relates to a numerically controlled attenuator based on capacitance compensation. Background technique [0002] The attenuator is an important part of the microwave control circuit, which is used to control the amplitude of the radio frequency signal. A common digitally controlled attenuator is to switch the signal between the reference state and the attenuation state through the switching device, so as to achieve the predetermined target signal amplitude attenuation. Ideally, the attenuator is equivalent to a lossless straight-through network in the reference state, and is equivalent to a resistive network with flat amplitude and phase characteristics in the attenuation state. Generally, for an attenuator with a relatively small attenuation range (less than 2dB), a simple parallel attenuation structure is used to realize a series structure of a switch and an attenuation resistor...

AI Technical Summary

Problems solved by technology

However, due to the existence of the parasitic capacitance of the switching transistor, the attenuator has a parasitic phase shift in different states, resulting in parasitic phase modulation, which has a greater impact especially in high frequency operation

[0003] The parasitic phase modulation of the traditional attenuator with small attenuation values ​​above can be improved by adjusting the size of the switch transistor, but this method requires the transistor switch to have an accurate model in different sizes, which increases the design cost and reduces the flexibility of the design , and this also sacrifices the performance of attenuation flatness, increases loss and has limited improvement in parasitic phase modulation

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