MOS Resistor Bank Load for HF Amplifier Gain Stabilization

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Solution Overview

Problem

Gains of amplifiers/mixers in radio frequency front end (RFFE) circuitry deviate across process, voltage, and temperature variations, affecting signal-to-noise distortion ratio (SNDR) in electronic devices.

Innovation Solution

A metal oxide semiconductor (MOS)-based resistor bank is used as a load to adjust the gain of amplifiers/mixers, regulating impedance and emulating desirable resistance variations across PVT variations by adjusting voltage on the gate terminal of the MOS-based resistor bank.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional amplifiers/mixers are used in RFFE circuitry, then the circuit structure is simple, but the gain deviates across PVT variations affecting SNDR

Engineering Contradiction:

Improvegain stabilityVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A regulated MOS-based load is introduced as an intermediary component between the amplifier/ mixer and the power supply. This regulated load acts as a mediator that compensates for PVT variations by adjusting its impedance characteristics in response to control signals, thereby stabilizing the gain without requiring complex feedback loops or multiple amplification stages

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the impedance parameter of the MOS-based load dynamically in response to PVT conditions. By adjusting the gate voltage of the MOS transistor in the regulated load, the effective resistance changes to compensate for gain deviations caused by process, voltage, and temperature variations, thus maintaining stable amplifier/mixer gain across operating conditions

Inventive Principle:

Principle #35Parameter changes

2Reliability

If gain regulation circuitry is added to stabilize amplifier gain, then SNDR improves, but the device complexity increases

Engineering Contradiction:

Improvesignal to noise distortion ratioVSAvoidcircuit components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The gain regulation function is merged with the existing load structure of the amplifier/mixer. Instead of adding a separate complex feedback control system, the invention combines the regulation capability directly into the MOS-based load, which is already part of the basic amplifier structure. This integration approach improves SNDR while minimizing additional circuit components

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The regulated MOS-based load performs self-adjustment to maintain stable gain. The load automatically modifies its impedance characteristics in response to PVT variations without requiring external complex control circuits. The simple control signal applied to the MOS gate enables the load to self-regulate and compensate for gain deviations, improving SNDR with minimal additional complexity

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS20250105811A1Regulated MOS-based load for stabilization of HF amplifier/mixer gain VS. pvt

Publication Date: 2025.03.27 APPLE INC

AI summary

Systems and methods are provided for using a metal oxide semiconductor based (MOS-based) resistor bank as a load of an amplifier/mixer to adjust the gain of the amplifier/mixer across PVT variations. The gain is adjusted by regulating the impedance of the MOS-based resistor bank to emulate a desirable resistance change over temperature across all PTV variations. The voltage adding on the gate of the MOS-based resistor bank is controlled so that the resistance of the MOS-based resistor bank is a desired value and follow a predetermined variation across the PVT variations.