Universal Filter Based on Compact CMOS Structure of VDDDA

Area of Science:

• Electronics
• Analog Integrated Circuit Design
• Signal Processing

Background:

• Existing voltage differencing differential difference amplifier (VDDDA) structures often lack compactness and simplicity.
• The multiple-input metal oxide semiconductor (MOS) transistor technique offers a path to simplified integrated circuit designs.

Purpose of the Study:

• To propose and validate a novel, compact universal filter circuit utilizing the voltage differencing differential difference amplifier (VDDDA).
• To demonstrate the filter's capability to achieve multiple frequency responses (LP, BP, BR, HP, AP) with independent parameter control.
• To compare simulation results with experimental data for verification.

Main Methods:

• Design and simulation of a universal filter employing two VDDDAs, one resistor, and two grounded capacitors using Cadence and a 0.18-µm TSMC CMOS process.
• Implementation and testing of the filter using commercial components (LM13700, AD830).
• Analysis of filter characteristics including frequency response, input/output impedance, noise, and distortion.

Main Results:

• The proposed filter achieves low-pass, band-pass, band-reject, high-pass, and all-pass responses with unity passband gain.
• Orthogonal control of natural frequency and bandwidth is achieved via separate transconductance adjustments without impacting passband gain.
• For a band-pass configuration, the filter exhibits an RMS noise of 46 µV, IMD3 of -49.5 dB, and a dynamic range of 73.2 dB.
• Simulation results closely match experimental findings, confirming the circuit's efficacy.

Conclusions:

• The presented VDDDA-based universal filter offers a compact and simple solution compared to existing CMOS structures.
• The design provides versatile filtering capabilities with independent control over key parameters.
• The agreement between simulated and experimental results validates the proposed filter's performance and practical applicability.