Differential Signal Output Circuit With Single-Phase Shutdown Control
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Solution Overview
Problem
Conventional signal output circuits require both npn and NMOS transistors for shutdown functionality, complicating manufacturing and limiting application to circuits using single-phase digital signals for switching between shutdown states.
Innovation Solution
A signal output circuit using only npn transistors, with an input buffer converting single-phase switching instructions into differential signals, a generation control circuit generating control voltages, and an output circuit switching between shutdown states based on these voltages, allowing for single-phase digital control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NMOS transistors are used for switching between shutdown states in addition to npn transistors, then shutdown functionality is achieved, but manufacturing process complexity increases
Solution Approach 1:
The patent applies homogeneity by using only npn transistors throughout the entire circuit, including for the switching function. The current source transistor (Q3) and its control mechanism are both implemented using npn transistors, eliminating the need for heterogeneous NMOS transistors. This uniform use of a single transistor type simplifies the manufacturing process while maintaining the shutdown functionality through voltage-controlled current modulation.
2Reliability
If differential switching signals are used for shutdown control, then reliable switching is achieved, but compatibility with single-phase digital signal circuits is reduced
Solution Approach 1:
The patent introduces an intermediary mechanism: a voltage divider circuit (R1, R2) that converts a single-phase digital control signal into a differential voltage swing at the base of transistor Q3. This intermediary voltage division approach allows the circuit to accept simple single-phase digital signals while internally generating the differential control action needed for reliable switching, thus bridging the gap between simple input signals and reliable differential control.
Solution Approach 2:
The patent utilizes parameter changes by modifying the voltage level and swing characteristics of the control signal through the voltage divider network. The single-phase digital signal undergoes parameter transformation (voltage division and differential conversion) to become an effective differential control signal, enabling the circuit to maintain reliability while accepting simpler input signals from a broader range of digital systems.
Data Source
AI summary
In a signal output circuit, an input buffer externally receives a single-phase switching instruction signal to switch a state of the output circuit a shutdown disable state or a shutdown enable state, and converts and outputs the single-phase switching instruction signal into a differential switching instruction signal. A generation control circuit outputs a generation control signal for controlling generation of a control voltage in the control voltage generation circuit based on the differential switching instruction signal. A control voltage generation circuit outputs the control voltage upon changing a value of the control voltage in accordance with a logic of the single-phase switching instruction signal. An output circuit externally receives a differential input signal, outputs a differential output signal upon impedance-converting the differential input signal, and switches between the shutdown disable state and the shutdown enable state of the differential input signal.