OTA Circuit Active Inductors for DDR5 Duty Cycle Distortion
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Solution Overview
Problem
Double data rate (DDR) 5 systems experience distortion in duty cycle due to differing electrical path lengths for operational transconductance amplifiers, and traditional inductors require high inductance at lower frequencies, occupying large areas and hindering miniaturization.
Innovation Solution
The use of active inductors, including P-channel and N-channel transistors, resistors, and capacitors, in operational transconductance amplifier circuits to enhance bandwidth and duty cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional inductors are used to reduce duty cycle distortion, then duty cycle characteristics are improved, but the inductors occupy large area and hinder miniaturization
Solution Approach 1:
The patent replaces traditional passive inductors with active inductors implemented using transistor circuits (specifically, a cross-coupled transistor configuration with capacitors). This changes the physical implementation from a component requiring large magnetic core area to an active circuit occupying minimal silicon area, thereby resolving the area occupation problem while maintaining the inductive function needed for duty cycle correction.
Solution Approach 2:
The patent substitutes the mechanical/magnetic inductor structure with an electronic active circuit implementation. The traditional inductor based on magnetic fields and physical windings is replaced by an active transistor-based circuit that synthesizes inductive behavior through feedback mechanisms, eliminating the need for large physical inductor components and enabling miniaturization.
2Stability of the object's composition
If inductors with high inductances are used to maintain constant impedances at lower frequencies, then impedance stability is improved, but the inductors occupy larger area
Solution Approach 1:
The patent uses active inductors with controllable parameters through transistor biasing and capacitor values. The equivalent inductance can be adjusted by changing transistor operating points and capacitor values, allowing high inductance values to be achieved with minimal physical area. This enables impedance stability at lower frequencies without requiring large physical inductors.
3Ease of operation
If different lengths of electrical paths are used in operational transconductance amplifiers, then circuit functionality is achieved, but distortion of duty cycle occurs
Solution Approach 1:
The patent introduces active inductors as intermediary elements within the operational transconductance amplifier circuit. These active inductors are strategically placed in the electrical paths to compensate for path length differences and impedance variations, acting as mediators that equalize the signal transmission characteristics and eliminate duty cycle distortion while preserving the necessary circuit functionality.
Data Source
AI summary
An amplifier circuit comprises a first unit circuit and a second unit circuit. The first unit circuit may include a first current mirror circuit that includes a first active inductor including a P-channel transistor, and a first input circuit configured to generate a first differential current and a second differential current based on a pair of differential input signals. The second unit circuit may include a second current mirror circuit that includes a second active inductor including a P-channel transistor, and a second input circuit configured to generate a third differential current and a fourth differential current based on the pair of differential input signals.