Charge-Steering Amplifier With Common-Mode Reference Coupling
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Solution Overview
Problem
Conventional charge-steering amplifiers are susceptible to perturbations in common-mode voltage, leading to reduced effective number of bits (ENOB) and linearity of gain due to transistor sensitivity.
Innovation Solution
Incorporating a sample-and-hold circuit, reference voltage generation circuit, and switch circuit to sample and amplify differential input signals, with the common-mode voltage being used to improve the charge-steering amplifier's performance by coupling it to the output terminals or load capacitors, thereby reducing the impact of common-mode voltage perturbations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional charge-steering amplifier is used, then the circuit structure is simple, but the susceptibility to common-mode voltage perturbation degrades performance and reduces ENOB
Solution Approach 1:
The patent introduces a reference voltage generation circuit as an intermediary component that generates a common-mode reference voltage based on the differential input signal. This reference voltage is then coupled to the output terminals through a switch circuit, acting as a mediator to counteract the effects of common-mode voltage perturbations on the transistors, thereby improving performance stability without fundamentally changing the core charge-steering amplifier structure.
Solution Approach 2:
The patent implements a feedback mechanism where the common-mode voltage of the differential input signal is detected and used to generate a reference voltage that is fed back to the output terminals. This feedback loop continuously compensates for common-mode voltage variations, maintaining stable transistor operation and improving ENOB while keeping the overall circuit structure relatively simple.
2Device complexity
If conventional charge-steering amplifier is used, then the circuit structure is simple, but the linearity of gain is reduced due to transistor sensitivity to common-mode voltage
Solution Approach 1:
The reference voltage generation circuit serves as an intermediary that processes the differential input signal to extract the common-mode voltage component and generates a compensating reference voltage. This reference voltage is coupled to the output terminals through switches, acting as a mediator to stabilize the transistor operating points and improve gain linearity without adding complex circuitry to the core amplifier path.
Solution Approach 2:
The patent dynamically adjusts the reference voltage parameter based on the common-mode voltage of the differential input signal. By changing the reference voltage level in response to common-mode variations, the transistor operating conditions are optimized to maintain linear gain characteristics, thereby improving manufacturing precision without increasing structural complexity.
3Reliability
If reference voltage generation circuit and switch circuit are added, then the linearity and stability are improved, but the device complexity increases
Solution Approach 1:
The reference voltage generation circuit is designed to perform multiple functions: it detects the common-mode voltage of the differential input signal, generates the appropriate reference voltage, and provides it to the output terminals. The switch circuit also serves dual purposes by coupling the reference voltage during normal operation and potentially resetting the output capacitors. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity while maintaining improved reliability.
4Object-affected harmful factors
If reference voltage is coupled to output terminals, then the susceptibility to common-mode voltage perturbation is reduced, but the device complexity increases
Solution Approach 1:
The switch circuit acts as an intermediary mechanism that conditionally couples the reference voltage to the output terminals. Instead of a permanent direct connection that would add continuous complexity, the switch provides controlled coupling only when needed, mediated by the switching action synchronized with the amplifier's operational phases. This approach reduces susceptibility to common-mode voltage perturbation while minimizing the increase in device complexity through selective rather than continuous intervention.
Data Source
AI summary
A charge-steering amplifier circuit and a control method thereof are provided. The charge-steering amplifier circuit is used for amplifying a differential input signal and includes a sample-and-hold circuit, a charge-steering amplifier, a reference voltage generation circuit, and a switch circuit. The sample-and-hold circuit is configured to sample the differential input signal to generate first and second sampled signals. The charge-steering amplifier has a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first and second input terminals receive the first and second sampled signals, respectively. The reference voltage generation circuit is configured to generate a reference voltage according to the differential input signal. The switch circuit is configured to couple the reference voltage to the first output terminal and the second output terminal.