1.2 V Differential Difference Transconductance Amplifier and Its Application in Mixed-Mode Universal Filter.

Area of Science:

• Electronics
• Analog Signal Processing
• Integrated Circuit Design

Background:

• Conventional transconductance amplifiers (TAs) have limitations.
• Differential difference amplifiers (DDAs) offer specific advantages.
• A combined approach using a differential difference transconductance amplifier (DDTA) can leverage benefits from both TA and DDA functionalities.

Purpose of the Study:

• To introduce a new mixed-mode universal filter topology.
• To utilize a novel differential difference transconductance amplifier (DDTA) as the core component.
• To achieve versatile filtering capabilities including voltage-mode (VM), current-mode (CM), transadmittance-mode (TAM), and transimpedance-mode (TIM) operations within a single circuit.

Main Methods:

• Design and simulation of a mixed-mode universal filter centered around a DDTA.
• Implementation of four distinct operation modes (VM, CM, TAM, TIM) within the proposed topology.
• Analysis of filtering responses, component matching conditions, and control of natural frequency and quality factor.
• Performance validation using PSPICE simulations with 0.18 µm CMOS technology and experimental verification with discrete DDTA-based integrated circuits.

Main Results:

• The proposed filter topology successfully implements four operation modes, yielding at least twenty distinct second-order filtering transfer functions.
• Absence of matching conditions for input and passive components simplifies the design.
• Orthogonal and electronic control of natural frequency and quality factor are demonstrated.
• Simulations show low power dissipation (66 µW) at a 1.2 V supply, and experimental tests confirm the filter's workability.

Conclusions:

• The presented DDTA-based mixed-mode universal filter offers significant flexibility and performance advantages.
• The design is suitable for low-voltage, low-power applications.
• The achieved multi-mode and multi-response filtering capabilities make it a valuable contribution to analog signal processing.