Switch Regulator Circuit for DAC Impedance Matching
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Solution Overview
Problem
High-resolution DACs face accuracy issues due to impedance mismatch in switches caused by the back-body voltage effect, which is impractical to address through transistor isolation, leading to reduced performance below 16-bit levels.
Innovation Solution
A switch regulator circuit that compensates for the body voltage effect by determining and adding a correction to the control voltage, ensuring matched impedance between transistors, using a regulator core circuit and output circuit to adjust the gate drive voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If transistor isolation is used to address back-body voltage effect, then impedance matching is improved, but device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The patent introduces a regulator circuit as an intermediary component between the digital-to-analog converter switches and the signal path. This regulator circuit actively compensates for the back-body voltage effect by adjusting the gate voltage of the switches, thereby maintaining impedance matching without requiring complex physical isolation structures. The regulator acts as a mediator that eliminates the need for isolated transistor wells or separate isolation circuits.
Solution Approach 2:
The patent dynamically adjusts the gate voltage parameter of the switches through the regulator circuit to compensate for body voltage effects. By changing the gate voltage in response to detected impedance variations, the system maintains optimal impedance matching across different operating conditions without requiring fixed structural modifications like transistor isolation.
2Measurement precision
If high-resolution DAC performance is achieved, then measurement precision is improved, but impedance mismatch due to back-body voltage effect worsens accuracy
Solution Approach 1:
The patent implements a feedback mechanism where the regulator circuit continuously monitors the impedance conditions of the DAC switches and adjusts the gate voltage accordingly. This feedback loop compensates for the back-body voltage effect in real-time, ensuring that impedance matching is maintained throughout operation, thereby preserving high measurement precision and DAC resolution accuracy.
Solution Approach 2:
The regulator circuit performs preliminary adjustment of the gate voltage before the switches are fully activated in the DAC signal path. By pre-compensating for the body voltage effect before the switches engage in critical signal switching, the system ensures that impedance matching is already optimized when high-resolution conversion occurs, preventing accuracy degradation.
3Object-affected harmful factors
If transistor isolation structures are implemented, then back-body voltage effect is reduced, but ease of manufacture and device complexity are worsened
Solution Approach 1:
Instead of implementing complex isolation structures around the transistors, the patent uses a regulator circuit as an intermediary that electrically compensates for the back-body voltage effect. This approach eliminates the need for additional isolation fabrication steps, making the manufacturing process simpler while still effectively reducing the harmful body voltage effects through active compensation.
Data Source
AI summary
A circuit includes an amplifier, a first transistor, a second transistor, and a third transistor. The amplifier has a first amplifier input coupled to a voltage reference terminal; a second amplifier input, and an amplifier output. The first transistor has a first terminal coupled to a power terminal, a second terminal coupled to the second amplifier input, a body terminal coupled to a reference terminal, and a control terminal coupled to the amplifier output. The second transistor has a first terminal coupled to the power terminal, a second terminal, a body terminal coupled to the second terminal of the second transistor, and a control terminal coupled to the amplifier output. The third transistor has a first terminal coupled to the second amplifier input, a second terminal coupled to the reference terminal, and a control terminal coupled to the second terminal of the second transistor.