Low-Impedance Driver Amplifier Using Stacked CMOS Transconductance
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Solution Overview
Problem
The elevated frequencies of the 5G-NR cellular standard pose challenging requirements for signal transmission, particularly for power amplifiers in mobile communication devices, as they necessitate inter-stage impedance matching networks that increase physical costs, consume power, and impose bandwidth limitations.
Innovation Solution
A driving amplifier stage with low output impedance is achieved by using stacked transconductance devices, such as complementary metal oxide semiconductor (CMOS) field effect transistors (FETs), which reuse supply current to provide an intermediate signal with high current and moderate voltage swing, eliminating the need for an inter-stage impedance matching network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inter-stage impedance matching network is used between the driving amplifier stage and output amplifier stage, then signal transmission quality is improved, but device complexity and physical cost increase
Solution Approach 1:
The patent extracts and eliminates the inter-stage impedance matching network from the transmission chain by redesigning the driving amplifier stage to inherently provide the necessary impedance transformation through stacked transconductance devices, thereby simplifying the overall device structure while maintaining signal transmission quality
Solution Approach 2:
The patent changes the output impedance parameter of the driving amplifier stage by using stacked transconductance devices configured to provide a low output impedance that directly matches the requirements of the output amplifier stage, eliminating the need for additional impedance matching networks
2Reliability
If an inter-stage impedance matching network is used, then signal transmission is improved, but power consumption increases
Solution Approach 1:
The patent removes the power-consuming inter-stage impedance matching network by integrating impedance transformation functionality into the driving amplifier stage itself through stacked transconductance devices, thereby reducing overall power consumption while maintaining signal transmission performance
Solution Approach 2:
The driving amplifier stage performs self-impedance transformation through its stacked transconductance device configuration, eliminating the need for separate impedance matching components and their associated power consumption
3Reliability
If an inter-stage impedance matching network is used, then signal quality is maintained, but bandwidth is limited
Solution Approach 1:
The patent extracts the bandwidth-limiting inter-stage impedance matching network and replaces it with a direct coupling approach using stacked transconductance devices that provide both impedance transformation and broadband signal transmission capabilities
Solution Approach 2:
The patent changes the impedance characteristics of the driving amplifier stage output to directly match the output amplifier stage input requirements across a broad frequency range, eliminating the bandwidth limitations imposed by traditional impedance matching networks
4Reliability
If an inter-stage impedance matching network is used, then impedance matching is achieved, but physical cost and size increase
Solution Approach 1:
The patent merges the impedance transformation function with the driving amplifier stage by using stacked transconductance devices that simultaneously provide amplification and impedance transformation, eliminating the need for separate impedance matching networks and reducing physical cost
Solution Approach 2:
The stacked transconductance devices in the driving amplifier stage serve multiple functions including signal amplification, impedance transformation, and direct driving of the output amplifier stage, thereby eliminating the need for dedicated impedance matching components
Data Source
AI summary
A driving amplifier with low output impedance is disclosed. In one aspect, a driving amplifier stage that does not need an inter-stage impedance matching network between the driving amplifier stage and an output amplifier stage in a transmission chain may be achieved by providing stacking transconductance devices within the driving amplifier stage and reusing a supply current to provide an intermediate signal with high current but moderated voltage swing to drive the output amplifier stage. In specifically contemplated aspects, the stacked transconductance devices may be complementary metal oxide semiconductor (CMOS) field effect transistors (FETs).