25% Duty Cycle Passive Mixer Loaded with Positive Feedback Transimpedance Amplifier Stage

Abstract

The invention discloses a passive frequency mixer at a duty ratio of 25% with a positive feedback transimpedance amplification stage as a load. The passive frequency mixer comprises a transconductance amplification stage, a switch frequency mixing stage and a transimpedance amplification stage, wherein the transconductance amplification stage adopts an inverter transconductance amplification structure and outputs radio frequency current; the switch frequency mixing stage adopts a switch tube cascaded structure respectively driven by orthogonal local oscillator signals at the duty ratio of 50%, the switch frequency mixing at the duty ratio of 25% is implemented, the radio frequency current output by the transconductance amplification stage is modulated, and the intermediate frequency current is output; the transconductance amplification stage adopts a cross coupling positive feedback structure, and the low input impedance is implemented at lower power consumption, so that the intermediate frequency current output by the switch frequency mixing stage is effectively converted to the intermediate frequency voltage to be output. The passive frequency mixer at the duty ratio of 25% with the positive feedback transimpedance amplification stage as the load has the characteristics of low power consumption, high gain and low noise.

Description

technical field [0001] The invention relates to a frequency conversion receiver, in particular to a 25% duty-cycle passive mixer with a positive feedback transimpedance amplifier stage as a load. Background technique [0002] With the continuous development of wireless communication technology, devices such as mobile phones, global positioning systems and wireless broadband networks play an increasingly important role in people's daily life. For these systems, low power consumption and low cost are extremely important indicators. Direct conversion receivers are widely used in modern mobile communication systems due to their low power consumption, high integration, and low cost, but they are also plagued by problems such as DC offset and 1 / f noise. In order to meet the low 1 / f noise requirements of direct conversion receivers, passive mixers are favored by designers because of their low 1 / f noise. [0003] In recent years, passive mixers with 25% duty ratio loaded by resist...

AI Technical Summary

Problems solved by technology

Among them, the switching tube is directly driven by the local oscillator signal with a 25% duty cycle. Since the local oscillator signal is a 25% duty cycle, the local oscillator buffer cannot use a limiting amplifier structure, but can only use an inverter structure. Increase the driving capability of the local oscillator signal, and the inverter structure needs to consume a lot of power to achieve the steep rising and falling edges of the local oscillator signal, which increases the power consumption of the system

In addition, the operational transconductance amplifier with resistor negative feedback has two disadvantages in addition to requiring large power consumption to obtain a sufficient gain-bandwidth product: First, the operational transconductance amplifier will generate a lot of noise, which directly reduces the noise performance of the mixer; second, the RF current at the input of the operational transconductance amplifier will feed through to its output through the load capacitance, creating an undesirable RF voltage at the output

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