Development of a CMOS Based on OTA for Bluetooth or WiFi Applications in 65nm Technology

Abstract

In the modern digital economy, the internet is the unifying strand for billions of people, which provides communication and access to information globally. The vast connectivity is largely made possible by wireless communication technologies, which are one of the main driving forces behind the advantages gained in our interconnected world. Harmonized guidelines for mobile devices allow people to use their devices almost everywhere on the planet. Bluetooth and Wi-Fi technologies are the cornerstones of wireless communication, guaranteeing uninterrupted device connections. Operational Transconductance Amplifiers (OTAs) are crucial in circuit design for Bluetooth and Wi-Fi usage as key elements in signal processing. Based on CMOS technology, OTAs offer versatile solutions that are particularly notable for their capability to transform voltage signals into current signals. This article provides a high-level design of a cascade current mirror Operational Transconductance Amplifier (OTA) for Bluetooth and Wi-Fi systems, based on a 65nm CMOS technology node. The design works towards improving the overall system performance by emphasizing crucial parameters like gain, power dissipation, area, and group delay. The suggested design lowers power consumption considerably and reduces the chip area occupied, along with lowering the group delay to enhance the responsiveness of the system. A significant gain increase is also obtained, providing enhanced signal amplification and overall performance for Bluetooth and Wi-Fi communication systems. This book showcases the significance of OTAs for maximizing the efficiency and performance of contemporary wireless telecommunication systems and emphasizes their significant role in establishing the next phase of Bluetooth and Wi-Fi development.

Introduction

Background and Motivation

In the 1990s, CMOS technology transitioned from baseband-only usage to being viable for high-frequency RF applications, thanks to reductions in transistor sizes to submicron levels. This shift enabled CMOS-based RF Integrated Circuits (RFICs) like Operational Transconductance Amplifiers (OTAs) to compete with bipolar and GaAs technologies. As devices became smaller and more power-sensitive—especially with the rise of portable electronics like smartphones and laptops—the need for low-power, low-voltage components grew, particularly in wireless technologies such as Bluetooth and WiFi.

2. Role of OTAs in Wireless Communication

Operational Transconductance Amplifiers (OTAs) are critical in low-power, high-frequency circuits because they offer:

• Adjustable transconductance

• High bandwidth and speed

• Low power usage

• Small chip area

• Suitability for integration in modern wireless systems

OTAs are essential in applications requiring amplification, filtering, and signal conversion, especially in Bluetooth and WiFi transceivers operating at 2.4 GHz.

3. Review of Related Work

Several studies have compared 65nm CMOS to older 90nm processes, showing clear advantages:

• Kim et al. (2023): Emphasized improved linearity and power efficiency in 65nm OTA designs for Bluetooth.

• Kulej et al. (2022): Proposed a linear OTA with 2.93μS transconductance, achieving high linearity and rail-to-rail operation in 65nm CMOS.

• Shankar et al. (2022) and Li et al. (2022): Compared 65nm and 90nm for WiFi, showing better power and signal performance in 65nm.

• Song et al. (2021): Developed a BLE receiver with 65nm, offering lower noise and better energy efficiency.

• Hu et al. (2021): Introduced a 28nm BLE receiver with very low power, validating trends of downscaling.

• Prasad et al. (2021): Demonstrated that 65nm provides better IRR and lower power compared to 90nm in Gm-C filter designs.

Conclusion from Literature: 65nm CMOS offers improved efficiency, integration, linearity, and power reduction, making it optimal for IoT and portable wireless devices.

4. Proposed OTA Design (65nm CMOS)

The paper presents a cascaded current mirror OTA designed and simulated using LTSpice XVII with 65nm CMOS technology. Key steps:

• Transistor sizing (W/L) was selected and tuned.

• DC and AC analyses were performed.

• Supply voltage used: 2.6V

Design Features:

• High gain and linearity due to cascaded architecture.

• Compact and energy-efficient layout suitable for Bluetooth/WiFi.

5. Simulation Results

A. DC Analysis:

• Output current ranged from 9.58mA to 9.61mA, indicating a stable design.

• A resistor was used at the output to measure current response.

B. AC Analysis:

• A 1pF capacitor was added to test frequency response.

• Key findings:

  • Operating frequency: 2.4 GHz

  • Gain: -20.09 dB

  • Phase: 111.5°

  • Group Delay: 62.27 ps

These results validate the OTA’s suitability for Bluetooth/WiFi transceivers at 2.4 GHz.

Conclusion

The project deals with the important aspect in electronic circuit design: the OTA, and its uses in the applications of Bluetooth and WiFi. The project studies the integration of CMOS technology with a view to optimizing the performance of an amplifier to sustain efficient wireless communication system operation. Bluetooth and WiFi technologies are commonly employed to link devices, and this paper presents a cascade current mirror CMOS operational transconductance amplifier (OTA) tailored for wireless communication systems operates in the 2.4GHz frequency band. The new OTA design is realized in 65nm CMOS technology and simulated with LTSpice software under a 2.6V supply voltage. The resulting performance specs for the OTA are a magnitude of -20.09dB, a phase of 111.50°, a Group Delay of 62.27ps, and a power dissipation of 27.09mW. This paper is proof of the feasibility of using the cascade current mirror configuration for improving the OTA\'s performance as an application to high-speed wireless communication systems, highlighting the relevance of accurate design and simulation as requirements for cutting-edge technology implementations.

References

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Copyright

Copyright © 2025 Mrs. D. Gowthami, L. Pravallika, E. Nishitha Reddy, B. Murali Karthik, SK. Sadhik. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.