Gilbert Switch Biasing With PMOS Trickle Current for Higher Gain

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Solution Overview

Problem

Existing Gilbert switch pairs face challenges in increasing conversion gain while maintaining low DC power consumption, as higher LO drive currents can hinder switching and lead to increased DC power consumption.

Innovation Solution

Incorporating cascoded PMOS trickle current sources controlled by DACs into the main transconductance and Gilbert switch stages, allowing for adjustable current injection into the output paths to enhance sensitivity and gain without significantly increasing DC power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the overall current of the mixer and the LO drive are increased to increase conversion gain, then the gain is improved, but the DC power consumption increases

Engineering Contradiction:

Improveconversion gainVSAvoidDC power consumption

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The patent changes the bias current parameter by introducing cascoded trickle current sources that provide a small DC bias current to the Gilbert switch stage. This allows the switches to operate at lower LO drive levels while maintaining full switching capability, thereby reducing DC power consumption without sacrificing conversion gain

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The cascoded trickle current sources act as intermediary components that inject a small bias current into the Gilbert switch stage. This intermediary current enables the switches to turn on fully at lower LO drive levels, allowing the system to achieve high conversion gain without requiring high overall mixer current and thus avoiding increased DC power consumption

Inventive Principle:

Principle #24Intermediary (Mediator)

2Power

If the LO swing is increased to switch the Gilbert switch harder and increase gain, then the gain is improved, but the DC power consumption increases

Engineering Contradiction:

ImprovegainVSAvoidDC power consumption

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The patent changes the biasing parameters of the Gilbert switch stage by adding cascoded trickle current sources. This modifies the operating point of the switches, enabling them to achieve full switching with lower LO swing amplitudes. The result is reduced DC power consumption while maintaining or improving gain performance

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10778148B1Gain and sensitivity in a Gilbert switch stage

Publication Date: 2020.09.15 RAYTHEON CO

AI summary

A power detector with a main transconductance stage and a Gilbert switch stage coupled to one another. Current sources are coupled between the main transconductance and the Gilbert switch stages. Each of the current sources is configured to generate a cascoded PMOS trickle current under the control of a DAC to control the effective voltage of the Gilbert switch stage. This mitigates the DC offsets resulting in enhanced sensitivity of the Gilbert switch stage. An increase in the conversion gain of a system using a Gilbert switch stage, for a given LO swing, is therefore obtained for a very small increase in DC power.