Non-linear Amplifier Stage for Ultra-low Power Implantable Receiver

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Leadless implantable medical devices face challenges in energy consumption due to the need for continuous communication between capsules, which results in high energy usage by transmitter/receiver circuits, exacerbated by signal attenuation and interference within the human body, limiting their longevity and efficiency.

Innovation Solution

A non-linear amplifier stage with a voltage inverter circuit and feedback resistor, combined with a Pulse Position Modulation (PPM) transmitter and a fast comparator demodulator, reduces energy consumption while maintaining high gain and bandwidth, enabling efficient human body communication with low power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional linear amplifier stages are used in the receiver module, then signal amplification is achieved, but energy consumption increases significantly

Engineering Contradiction:

Improveenergy consumptionVSAvoidcommunication reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent changes the operating parameters of the amplifier stage by biasing it at an intermediate voltage point rather than at the traditional linear operating point. This parameter change enables the amplifier to operate in a non-linear regime that consumes significantly less energy while still achieving the required signal amplification for reliable communication

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of using a linear amplifier that consumes high power, the patent inverts the approach by using a non-linear amplifier stage with complementary transistors operated in switching mode. This inversion of the conventional linear amplification approach achieves the same communication reliability with dramatically reduced energy consumption

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If the receiver module operates continuously to maintain communication readiness, then communication reliability is improved, but energy consumption increases

Engineering Contradiction:

Improvecommunication readinessVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic sampling of the incoming signal rather than continuous amplification. The non-linear amplifier stage is activated periodically to detect and amplify signal transitions, maintaining communication readiness while consuming energy only when needed, thus resolving the contradiction between continuous operation and energy savings

Inventive Principle:

Principle #19Periodic action

3Measurement precision

If high gain and bandwidth are maintained in the receiver, then signal detection accuracy is improved, but energy consumption increases

Engineering Contradiction:

Improvesignal detection accuracyVSAvoidenergy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent inverts the conventional approach by using a non-linear amplifier with complementary transistors that operates in switching mode. This inverted approach achieves high gain and bandwidth for accurate signal detection while consuming minimal energy, as the transistors switch between saturation and cutoff regions rather than operating in the linear active region

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the operating parameters of the amplifier to achieve high gain-bandwidth product at ultra-low power. By biasing the complementary transistor pair at an intermediate voltage and operating them in switching mode, the system achieves the required signal detection accuracy with dramatically reduced energy consumption compared to conventional linear amplifiers

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11027133B2Ultra-low power receiver module for wireless communication by an implantable medical device

Publication Date: 2021.06.08 CAIRDAC

AI summary

A receiver module of an autonomous implanted capsule receives a human body communication, HBC, signal sensed by an electrode in contact with body tissues or fluids of a patient. The signal is a pulse-modulated, baseband PPM pulse signal. The receiver module comprises a non-linear LNA amplifier stage comprising a pair of complementary transistors arranged as a voltage inverter circuit with an input coupled to the modulated-input-signal collecting electrode. The amplifier stage input is polarized to an intermediate operating point voltage between a supply voltage of the complementary transistor pair and a ground voltage. The amplifier stage has a gain of at least 40 dB, a gain-bandwidth product of at least 20 MHz, and a consumption lower than or equal to 100 nW. It is followed by a downstream demodulator stage made up of a fast comparator circuit of the Threshold Inverter Quantization, TIQ, type, comprising two inverters with cascade-coupled complementary transistors, one of the inverters operating as a voltage reference and the other inverter operating as a gain booster.