Output Driving Circuit Switching for Stable Bias Voltage Transitions
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Solution Overview
Problem
The increasing demand for low voltage I/O circuits due to semiconductor process scaling down leads to challenges in constructing I/O circuits that manage parasitic currents effectively, resulting in increased power consumption and the need for larger output driving circuits.
Innovation Solution
An output driving circuit is designed with multiple bias voltage generating circuits and a switching control circuit that selectively connects these circuits based on output voltage transitions, allowing for the transmission and reception of parasitic currents, thereby reducing their impact on bias voltages without using large static currents or decoupling capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low voltage I/O devices are used to construct I/O circuits, then cost is reduced and integration is improved, but parasitic currents are generated during voltage transitions that affect bias voltage stability
Solution Approach 1:
The bias voltage generating circuit is divided into multiple sub-circuits, each responsible for generating bias voltage during specific transition types (rising or falling). The switching control circuit selects and connects only the required sub-circuit based on the current transition type, thereby segmenting the parasitic current path and preventing it from affecting the entire bias voltage generation system.
Solution Approach 2:
The switching control circuit acts as an intermediary between the bias voltage generating sub-circuits and the output voltage generating circuit. It monitors the transition type and dynamically connects the appropriate sub-circuit to handle parasitic currents, isolating the bias voltage from parasitic current interference while maintaining proper biasing during transitions.
2Device complexity
If parasitic currents are allowed to flow during output voltage transitions, then device operation is simplified, but power consumption increases due to the need for larger output driving circuits
Solution Approach 1:
The parasitic current path is extracted and separated from the main bias voltage generation path. By providing a dedicated sub-circuit and switching mechanism, parasitic currents are directed through a separate path that does not interfere with the bias voltage, allowing the use of smaller output driving circuits and reducing overall power consumption.
3Reliability
If large static currents or decoupling capacitors are used to counteract parasitic current effects, then bias voltage stability is improved, but device area and power consumption increase
Solution Approach 1:
The bias voltage generating circuit transitions from a static configuration to a dynamic one, where the switching control circuit actively selects and connects the appropriate sub-circuit based on the real-time transition type. This dynamic adaptation allows the circuit to maintain bias voltage stability during transitions without requiring large static currents or decoupling capacitors, thereby reducing device area.
Data Source
AI summary
An output driving circuit includes: a plurality of bias voltage generating circuits configured to generate a plurality of bias voltages; a switching control circuit; and an output voltage generating circuit. The switching control circuit is configured to selectively connect one bias voltage generating circuit of the plurality of bias voltage generating circuits to the output voltage generating circuit based on an output voltage. The output voltage generating circuit is configured to transmit and receive a parasitic current generated due to transition of the output voltage to and from the one bias voltage generating circuit selectively connected to the output voltage generating circuit through the switching control circuit.