Analog Baseband Filter With Temperature-Compensated Common-Mode Control

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Solution Overview

Problem

Current Radio Frequency Integrated Circuits (RFICs) face challenges in reducing current consumption and size while maintaining performance, especially in communication systems using 16QAM or 64QAM, due to issues like temperature-dependent resistor properties causing common mode voltage variations and Local Oscillator (LO) leakage.

Innovation Solution

Integration of a Current-to-Voltage (I-V) converter and Power Gain Amplifier (PGA) into a single block using a resistor array, combined with a source follower circuit for temperature compensation, to maintain a constant common mode voltage and reduce current consumption and physical size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If an I-V converter and PGA are integrated into a single block using resistors, then current consumption and physical size are reduced, but temperature-dependent resistor properties cause common mode voltage variations and LO leakage

Engineering Contradiction:

Improvecurrent consumptionVSAvoidcommon mode voltage stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A feedback loop is implemented that senses the common mode voltage at the output of the integrated I-V converter and PGA, and adjusts the bias conditions of the PGA through a feedback amplifier to compensate for temperature-induced resistor variations. This closed-loop feedback mechanism maintains stable common mode voltage despite temperature changes.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The circuit dynamically adjusts operating parameters (bias currents and voltages) based on temperature conditions. By changing the bias parameters in response to temperature variations, the system compensates for resistor property changes and maintains stable common mode voltage performance.

Inventive Principle:

Principle #35Parameter changes

2Area of stationary object

If an I-V converter and PGA are integrated into a single block using resistors, then current consumption and physical size are reduced, but LO leakage occurs due to temperature changes

Engineering Contradiction:

Improvephysical sizeVSAvoidLO leakage

Core Design Contradiction:

Area of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The feedback loop detects common mode voltage variations that cause LO leakage and automatically adjusts PGA bias conditions to counteract these variations. This real-time feedback correction prevents LO leakage by maintaining proper common mode voltage levels despite temperature-induced changes.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The integrated circuit combines resistors with temperature compensation circuits and active feedback elements to create a composite structure that achieves both size reduction and temperature stability, preventing LO leakage while maintaining compact form factor.

Inventive Principle:

Principle #40Composite materials

3Reliability

If an OP-AMP is used in the PGA structure to ensure gain and dynamic range, then performance is maintained, but current consumption increases and circuit area expands

Engineering Contradiction:

Improvegain and dynamic range performanceVSAvoidcircuit area

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The I-V converter and PGA are merged into a single integrated block, eliminating the need for separate operational amplifiers and reducing overall circuit area. The combined structure achieves the required gain and dynamic range performance through integrated transistor-level implementation rather than discrete op-amp stages.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The design replaces traditional mechanical/op-amp-based PGA structures with a transistor-level integrated circuit implementation. This substitution eliminates bulky operational amplifiers while maintaining performance through carefully designed current mirrors and transistor gain stages.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach effectively reduces current consumption and physical size of RFICs while preventing LO leakage by maintaining a constant common mode voltage despite temperature changes, ensuring efficient performance in multi-mode multi-band radio transceivers.

Implementation Method 1

adjusting a gain of an output voltage of the current-voltage conversion amplifier using a plurality of resistors

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

a source follower circuit compensating for temperature for the output voltage of the current-voltage conversion amplifier

Methodology Applied

Scientific EffectTemperature compensation:

Data Source

PatentUS9197174B2Analog baseband filter for radio transceiver

Publication Date: 2015.11.24 SAMSUNG ELECTRONICS CO LTD

AI summary

An analog baseband filter for a radio transceiver is provided. An analog baseband filter for a multi-mode multi-band radio transceiver includes a current-voltage conversion amplifier converting a current received at the analog baseband filter into a voltage and adjusting a gain of an output voltage of the current-voltage conversion amplifier using a plurality of resistors, and a source follower circuit compensating for temperature for the output voltage of the current-voltage conversion amplifier.