Passive Reflection Mixer With LO Pulse Shaping and Isolation
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Solution Overview
Problem
Existing passive FET mixers face challenges in achieving high dynamic range, low distortion, and efficient frequency conversion with reduced LO drive levels, often requiring complex filtering and high LO power, while also suffering from intermodulation distortion and poor LO isolation.
Innovation Solution
A novel double-balanced passive reflection mode FET mixer with a 0/180 degree phase splitting transformer and pulse shaping circuitry, using dual-tuned networks and parallel R-C networks to improve energy transfer and reduce non-linearity, allowing for efficient LO signal processing and isolation without substantial LO power increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a passive FET mixer is designed to reduce LO drive levels, then energy efficiency improves, but intermodulation distortion increases and dynamic range deteriorates
Solution Approach 1:
The patent applies dynamic pulse shaping to the LO signal, transforming it from a static sinusoid into a time-varying pulse train with optimized rise/fall times. This dynamic modification allows the mixer to achieve superior intermodulation performance at reduced LO power levels by concentrating energy into sharp transitions that improve switching efficiency without requiring increased overall power
Solution Approach 2:
The invention changes the temporal parameters of the LO signal by applying pulse shaping with specific rise and fall times (typically 0.1-10 ns). This parameter transformation optimizes the LO waveform to reduce intermodulation distortion while maintaining lower drive levels, effectively decoupling the relationship between LO power and IMD performance
2Reliability
If a passive FET mixer uses traditional filtering to reduce intermodulation products, then intermodulation distortion improves, but device complexity and insertion loss increase
Solution Approach 1:
The patent performs preliminary intermodulation suppression by shaping the LO pulse parameters before the mixing occurs. By optimizing the LO waveform characteristics in advance, the mixer inherently generates fewer intermodulation products, eliminating the need for subsequent complex filtering stages and reducing overall system complexity
3Use of energy by moving object
If a passive FET mixer operates without substantial LO power increase, then energy efficiency improves, but LO isolation and suppression of intermediation products deteriorate
Solution Approach 1:
The patent employs periodic pulse shaping of the LO signal, creating a regular train of optimized pulses with controlled duty cycles. This periodic structure enhances the spectral characteristics of the LO signal, improving frequency selectivity and suppressing spurious intermediation products while maintaining energy efficiency through the pulsed rather than continuous operation
Data Source
AI summary
In one aspect, a mixer that provides improved isolation between an input oscillator and a mixing cell. In another aspect, a mixer that includes circuitry operative to shape an input signal provided by a local oscillator.