Amplitude Setting Circuit With Temperature-Compensated Bias Control
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Solution Overview
Problem
Conventional amplitude setting circuits in ASK modulation systems experience variations in output signal amplitude due to temperature changes, affecting the stability of the amplitude level.
Innovation Solution
An amplitude setting circuit is designed with a configuration that includes an inverter, drive transistors, and a voltage divider, utilizing resistors and diode-connected transistors to maintain a predetermined current relationship, which stabilizes the output signal against temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional amplifiers with fixed gain are used to set amplitude levels, then the circuit structure is simple, but the output signal amplitude varies with temperature changes
Solution Approach 1:
The patent changes the operating parameters of the amplifier circuit by introducing temperature-compensation components (diodes and resistors) that adjust the bias conditions. The diodes are biased to produce voltage drops that compensate for temperature-induced gain variations, thereby maintaining stable amplitude output across different temperatures while keeping the overall circuit structure relatively simple.
Solution Approach 2:
The patent implements a feedback mechanism where the temperature-dependent voltage drops across the diodes are fed back to the amplifier's bias circuitry. This feedback loop automatically adjusts the amplifier's operating point in response to temperature changes, counteracting gain variations and stabilizing the output amplitude without requiring complex external control systems.
2Adaptability or versatility
If variable gain amplifiers are used to adjust amplitude levels, then the amplitude can be dynamically controlled, but the circuit complexity increases
Solution Approach 1:
The patent achieves dynamic amplitude control by changing the bias parameters of the amplifier through temperature-compensated voltage dividers. By adjusting the resistor values in the voltage divider network, the amplifier's gain can be dynamically controlled while the diode-based temperature compensation ensures that the control relationship remains stable across temperatures, avoiding the need for complex variable gain amplifier circuits.
3Reliability
If temperature compensation components are added to stabilize amplitude, then the amplitude stability improves, but the circuit complexity increases
Solution Approach 1:
The patent achieves temperature compensation by changing the electrical parameters (voltage drops) of diode components that are naturally temperature-dependent. These diodes are biased to produce voltage drops that directly compensate for the temperature-induced parameter changes in the amplifier, providing automatic temperature compensation with minimal additional components.
Solution Approach 2:
The temperature compensation mechanism is self-regulating, utilizing the inherent temperature-dependent characteristics of diodes to automatically counteract temperature effects on the amplifier gain. The circuit serves itself by converting the temperature-dependent voltage drops into compensating signals without requiring external temperature sensing or active control elements.
Data Source
AI summary
An amplitude setting circuit for setting an amplitude level of its output signal corresponding to an input signal. By setting a current flowing through a first diode-connected transistor (Q5) and a current flowing through a first drive transistor (Q1) to be in a predetermined relationship, variation with temperature in potential at a first connection point of the first drive transistor (Q1) and a first conductivity-type transistor (M1) is removed, and by setting a current flowing through a second diode-connected transistor (Q6) and a current flowing through a second drive transistor (Q4) to be in a predetermined relationship, variation with temperature in potential at a second connection point of a second conductivity-type transistor (M2) and the second drive transistor (Q4) is removed.