Differential Amplifier Canceling Circuit for Leakage-Free Test Mode
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In transceiver devices, unbalanced voltages at differential nodes of amplifiers when turned off can cause leakage currents, leading to inaccuracies in performance determination during testing due to induced leakage current affecting the attenuator.
Innovation Solution
An amplifier design incorporating a pair of input transistors, a load, and a canceling circuit that balances voltages at differential nodes when the amplifier is turned off, utilizing transistors and capacitors to couple input signals and manage bias voltages for effective voltage balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the amplifier is turned off during test mode, then power consumption is reduced and testing can be performed, but unbalanced voltages at differential nodes cause leakage current that affects measurement accuracy
Solution Approach 1:
The canceling circuit is activated before the amplifier is turned off to balance the voltages at the differential nodes. This preliminary action prevents the generation of leakage current that would otherwise occur when the amplifier is off, thereby maintaining measurement accuracy during test mode while still achieving power savings.
Solution Approach 2:
The canceling circuit acts as an intermediary component that specifically addresses the voltage imbalance issue. It is coupled between the differential nodes and actively balances their voltages, serving as a mediator that allows the amplifier to be turned off without causing harmful leakage current effects on the attenuator and measurement accuracy.
2Measurement precision
If the amplifier remains on during testing, then voltage balance is maintained and no leakage current is generated, but power consumption increases and prevents effective test mode operation
Solution Approach 1:
The amplifier system is segmented into the main amplifier function and the separate canceling circuit function. This allows the main amplifier to be turned off for power savings while the canceling circuit independently maintains voltage balance at the differential nodes, preventing leakage current without requiring the entire amplifier to remain on.
Solution Approach 2:
The canceling circuit provides a self-service solution by automatically detecting and correcting voltage imbalances at the differential nodes. It operates autonomously to maintain the necessary voltage balance condition, allowing the amplifier to be turned off without manual intervention or complex control mechanisms.
3Measurement precision
If a canceling circuit is added to balance voltages, then leakage current is reduced and measurement accuracy improves, but device complexity increases
Solution Approach 1:
The canceling circuit changes the voltage parameters at the differential nodes by actively balancing them. It adjusts the voltages to be equal when the amplifier is off, thereby preventing the voltage differential that causes leakage current. This parameter change approach achieves measurement accuracy improvement without requiring fundamental architectural changes to the amplifier.
Solution Approach 2:
The canceling circuit implements a feedback mechanism that continuously monitors the voltages at the differential nodes and adjusts them to maintain balance. This feedback control ensures that voltage imbalances are automatically corrected, preventing leakage current generation while keeping the circuit design relatively simple and manageable.
Data Source
AI summary
An amplifier is provided. The amplifier includes a pair of first input transistors, a first load, and a first canceling circuit. The pair of first input transistors is coupled between a pair of first differential nodes and a reference voltage source, for receiving a pair of input signals. The first load is coupled to the pair of first differential nodes and a pair of differential output terminals of the amplifier. The first canceling circuit is coupled between the first differential nodes. The canceling circuit is capable of balancing voltages, respectively, at the first differential nodes when the amplifier is turned off.