RF Transceiver Front End with Implicit Direction Control

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Solution Overview

Problem

Existing RF transceivers require multiple antennas and passive matching elements, as well as high-frequency analog signal switches, which increase costs and device area, and fail to efficiently share matching elements for both communication directions.

Innovation Solution

The design integrates a single antenna and matching elements for both transmit and receive paths using a cascode transistor configuration for the Power Amplifier and a common-gate PMOSFET configuration for the Low Noise Amplifier, with implicit direction control through bias voltage manipulation, eliminating the need for TX/RX switches and minimizing component count.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple antennas and passive matching elements are used for separate transmit and receive paths, then signal quality and communication reliability are improved, but device area and manufacturing cost increase

Engineering Contradiction:

Improvecommunication reliabilityVSAvoiddevice area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent combines transmit and receive paths into a single shared antenna and matching element structure. The same antenna and passive matching elements serve both TX and RX functions by being time-multiplexed between the two communication directions, thereby reducing device area while maintaining communication reliability through proper isolation during simultaneous operations

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The antenna and passive matching elements are designed to perform multiple functions - serving both as transmit antenna and receive antenna, and as matching elements for both TX and RX paths. This multi-functionality is achieved through time-division multiplexing where the same physical components are dynamically allocated to different functions based on communication direction

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If TX/RX switches are used to commutate transfer direction, then direction isolation is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvedirection isolationVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the TX/RX switch component from the system by using implicit direction control through bias voltage manipulation. The switching function is replaced by controlling the operational state of amplifiers via bias voltages, thereby reducing device complexity while maintaining direction isolation through proper amplifier state management

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical/electrical switch system with a voltage-controlled system. Instead of using physical switches to commutate between TX and RX paths, the invention uses bias voltage manipulation to control the operational state of amplifiers, substituting a simpler voltage control mechanism for a more complex switching mechanism

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If separate matching elements are used for transmit and receive paths, then path optimization is improved, but manufacturing cost and device area increase

Engineering Contradiction:

Improvepath optimizationVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The passive matching elements are designed to serve both transmit and receive paths universally. The same matching elements are used for impedance matching in both TX and RX configurations, reducing manufacturing cost and device area while maintaining path optimization through careful design that accounts for both operational modes

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Area of stationary object

If a single antenna is shared for both transmit and receive, then device area and cost are reduced, but direction isolation and signal quality deteriorate

Engineering Contradiction:

Improvedevice areaVSAvoiddirection isolation

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The patent employs time-division multiplexing where the single antenna and matching elements are periodically alternated between transmit and receive modes. During TX periods, the transmit path is activated; during RX periods, the receive path is activated. This periodic switching maintains direction isolation while enabling single antenna usage, thereby reducing device area without sacrificing communication reliability

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS8711831B2Front end for RF transmitting-receiving systems with implicit directional control and time-multiplexing method in submicron technology

Publication Date: 2014.04.29 MAXIM INTEGRATED PROD GMBH

AI summary

A new design configuration of an RF-transceiver front end is proposed. The Power Amplifier (PA) output stage of the transceiver comprises a cascode circuitry of N-type transistors with open-drain-configuration. The cascode-transistor is acting as a common-gate-transistor, whose gate is controlled to block the transmitting-(TX) path. The Low Noise Amplifier (LNA) input stage uses a common-gate configuration of a p-channel MOS-transistor that is controlled by the voltage at the bulk terminal. Lifting the bulk potential of this PMOS-transistor above its source potential disables the receiving-(RX)-path. This design allows low cost implementation for TDMA-RF-transceivers especially for Bluetooth-Solutions. The number of external components is reduced. No additional TX/RX switch is required. The same port and the same matching elements for the antenna's bandwidth adaptation are used for both the TX-path and the RX-path.