Low-Voltage RF Signal Path With Regulated Current-Mode Bias

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Solution Overview

Problem

RF signal generators, particularly arbitrary waveform generators, face challenges in reducing supply voltage levels and power consumption, especially in cryogenic applications for quantum computing, where current-mode circuitry requires high supply voltages to maintain transistor saturation mode.

Innovation Solution

The integration of a voltage-mode filter circuit with a current-mode output circuit, utilizing a regulation circuit to maintain a constant gate-source bias voltage, allows for reduced supply voltage levels and power consumption by eliminating the need for high voltage headroom and optimizing transistor operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If current-mode circuitry is used to improve power efficiency through current reuse, then power efficiency is improved, but supply voltage requirements increase due to stacked transistor architectures requiring high headroom to operate transistors in saturation mode

Engineering Contradiction:

Improvepower efficiencyVSAvoidsupply voltage

Core Design Contradiction:

Use of energy by moving objectVSPower

Solution Approach 1:

The patent divides the circuit into separate voltage-mode and current-mode sections. The voltage-mode filter circuit processes signals at lower voltages, while the current-mode output circuit handles power-efficient signal generation. This segmentation allows each section to operate in its optimal mode without requiring high supply voltages throughout the entire system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a voltage-to-current conversion stage as an intermediary between the voltage-mode filter circuit and the current-mode output circuit. This intermediary converts the voltage signal from the filter into a current signal that can be processed efficiently by the current-mode circuitry, enabling the system to achieve both low voltage operation and high power efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by stationary object

If supply voltage levels are reduced to decrease power consumption, then power consumption is reduced, but transistor saturation mode operation becomes difficult to maintain in current-mode circuitry

Engineering Contradiction:

Improvepower consumptionVSAvoidtransistor operation stability

Core Design Contradiction:

Use of energy by stationary objectVSReliability

Solution Approach 1:

The patent segments the circuit architecture into voltage-mode and current-mode sections, allowing the voltage-mode filter to operate at reduced supply voltages (500mV-700mV) without compromising the operation stability of current-mode transistors. This segmentation enables low-power operation while maintaining reliable transistor saturation mode operation in the current-mode output circuit.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the operating parameters of different circuit sections independently. The voltage-mode filter operates at low supply voltages with appropriate biasing, while the current-mode output circuit maintains its required voltage headroom through separate power supply rails. This parameter differentiation allows reduced overall power consumption while preserving transistor operation stability.

Inventive Principle:

Principle #35Parameter changes

3Power

If voltage-mode filter circuit is used to reduce supply voltage requirements, then supply voltage requirements are reduced, but interfacing with current-mode output circuit becomes complex due to mode conversion requirements

Engineering Contradiction:

Improvesupply voltageVSAvoidcircuit interfacing complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent employs a voltage-to-current conversion circuit as an intermediary stage between the voltage-mode filter and current-mode output. This intermediary handles the mode conversion in a dedicated, standardized manner, simplifying the overall interfacing complexity compared to attempting direct integration or using complex dual-mode circuits throughout the system.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent extracts the voltage-to-current conversion function into a separate, dedicated stage rather than attempting to integrate it throughout the circuit. This extraction isolates the complexity of mode conversion to a specific location, making the interfacing between voltage-mode and current-mode sections more manageable and modular.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS11777496B1Low voltage signal path in a radio frequency signal generator

Publication Date: 2023.10.03 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A device comprises a voltage-mode filter circuit, a current-mode output circuit, and a regulation circuit. The voltage-mode filter circuit is configured to generate a voltage signal on an output terminal thereof. The current-mode output circuit comprises an input transistor which comprises a gate terminal coupled to the output terminal of the voltage-mode filter circuit, and a source terminal coupled to a regulated node. The regulation circuit is configured to adjust a voltage level on the regulated node to maintain a constant gate-source bias voltage for the input transistor to generate a current for biasing the current-mode output circuit.