Switched-Capacitor Bias Circuit for Stable Gm/C Over PVT
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Integrated circuit designs face challenges in maintaining a constant transconductance to load capacitance ratio over process and temperature variations, requiring additional hardware and complex tuning mechanisms, which increase silicon area and power consumption.
Innovation Solution
A biasing generator circuit utilizing PMOS and NMOS switched capacitor reference circuits, along with a transconductor reference cell, provides a constant transconductance to load capacitance ratio without the need for additional hardware or calibration, using a combiner element and a low-dropout regulator to stabilize filter characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional biasing circuits are used to maintain constant transconductance to load capacitance ratio, then process and temperature stability is improved, but additional hardware and complex tuning mechanisms are required which increase silicon area and power consumption
Solution Approach 1:
The biasing generator circuit automatically adjusts transconductance values through self-biasing mechanisms, eliminating the need for external calibration hardware. The circuit uses intrinsic device characteristics and feedback loops to maintain constant gm/C ratios without requiring additional tuning components or complex control mechanisms.
Solution Approach 2:
The invention changes the operating parameters of transistors dynamically by adjusting bias voltages and currents based on process and temperature variations. This allows the transconductance to load capacitance ratio to remain constant despite environmental changes, without requiring additional hardware for compensation.
2Stability of the object's composition
If traditional biasing circuits are used to maintain constant transconductance to load capacitance ratio, then process and temperature stability is improved, but silicon area increases due to additional hardware
Solution Approach 1:
The biasing generator circuit performs multiple functions using a single integrated structure: it generates bias voltages, compensates for process variations, maintains constant transconductance ratios, and provides temperature stabilization. This multi-functionality eliminates the need for separate compensation circuits and tuning mechanisms, reducing overall silicon area.
3Stability of the object's composition
If traditional biasing circuits are used to maintain constant transconductance to load capacitance ratio, then process and temperature stability is improved, but power consumption increases
Solution Approach 1:
The biasing generator uses periodic switching of capacitor arrays to adjust transconductance values, rather than continuous adjustment mechanisms. This periodic action reduces power consumption by eliminating continuous current flow through tuning components while still achieving process and temperature compensation.
Data Source
AI summary
Bias circuit and a bias generator circuit comprising such a bias circuit. The bias circuit (10, 11) comprises a switched capacitor resistor circuitry (C1, C2, M12-M17), and an operational amplifier (M1-M4, M10) with an input differential transistor pair (M1, M2). The bias circuit further comprises additional source follower transistors (M5, M6) associated with the first and second input differential transistors (M1, M2). The bias generator circuit has a PMOS switched capacitor reference circuit (11) and a NMOS switched capacitor reference circuit (10) and a transconductor reference cell (15). The transconductor reference cell (15) is a replica of a basic reference cell used in a further circuit.