Driver Comparator Circuit for Round-Trip Delay Cancellation
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Solution Overview
Problem
In bidirectional signal transmission between semiconductor devices, existing methods suffer from round trip delay issues due to the need to switch signal transmission direction, leading to increased test periods and reduced throughput in testing apparatuses.
Innovation Solution
A driver comparator circuit is designed with a voltage dividing circuit and a load balancer, along with a driver amplifier and comparator, to cancel out the signal component transmitted by the driver amplifier, allowing the comparator to compare only the signal component from the communication target device with a threshold voltage, thereby reducing the effects of round trip delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the output of the driver is set to a predetermined fixed terminal voltage during signal transmission, then bidirectional transmission is achieved, but round trip delay occurs leading to increased test period and reduced throughput
Solution Approach 1:
The patent extracts and removes the driver's own transmitted signal from the received signal using a subtractor circuit. This allows the comparator to process only the signal from the DUT, eliminating the need to wait for signal direction switching and thereby reducing round trip delay and test period.
Solution Approach 2:
The patent introduces intermediate circuits including a voltage dividing circuit, subtractor, and level shifting circuit between the driver output and comparator input. These intermediary components process the combined signal to separate and eliminate the driver's own signal component, enabling continuous operation without direction switching delays.
2Device complexity
If the driver and comparator share a common transmission line for bidirectional communication, then device complexity is reduced, but the comparator is affected by the driver's output signal
Solution Approach 1:
The subtractor circuit extracts and removes the driver's transmitted signal component from the combined signal received at the comparator. This extraction process eliminates interference from the driver's output, allowing the comparator to accurately measure and compare only the DUT's signal without being affected by the shared transmission line.
Solution Approach 2:
The patent uses feedback by taking a portion of the driver's output signal through the voltage dividing circuit and feeding it to the subtractor. This feedback mechanism enables the subtractor to cancel out the driver's signal component in real-time, ensuring accurate comparison of the DUT's signal despite the shared transmission line.
Data Source
AI summary
A first resistor is arranged such that a first voltage is applied to a first terminal thereof, and a second terminal thereof is connected to an input/output terminal. The first voltage is applied to a first terminal of a second resistor. A tail current source generates a predetermined tail current. A current switch receives data to be transmitted to a second device, selects one from among the second terminals of the first and second resistors, and connects the terminal thus selected to the tail current source. A voltage dividing circuit includes a third resistor and a fourth resistor provided in series between the second terminals of the first resistor and the second resistor. A load balancer includes a fifth resistor arranged such that a second voltage is applied to a first terminal thereof, and a second terminal thereof is connected to the second terminal of the second resistor.