Oscillation Circuit Feedback for Stable Frequency Under Voltage Drift
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Solution Overview
Problem
Existing oscillation circuits using bipolar or MOS transistors are susceptible to variations in power supply voltage and temperature, leading to potential linear operation of transistors and frequency instability due to increased collector or drain voltages.
Innovation Solution
The oscillation circuit incorporates a P-type transistor with feedback between its collector and base, or drain and gate, to lower the collector or drain voltage, and includes a resistance element and variable current sources to stabilize operation points and temperature characteristics, ensuring the transistor operates within a saturation region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a collector voltage of the bipolar transistor increases, then the transistor can operate with higher power, but the circuit operation is influenced and frequency variation occurs
Solution Approach 1:
The patent implements feedback by connecting the collector of the bipolar transistor to the gate of the P-type transistor, which in turn connects to the base of the bipolar transistor. This feedback path allows the circuit to automatically regulate the collector voltage, preventing excessive voltage increases that would cause frequency variation and maintain stable oscillation frequency despite power changes.
Solution Approach 2:
The patent changes the operating parameters by introducing a P-type transistor to actively control the collector voltage through gate-source voltage regulation. This parameter control mechanism ensures the collector voltage remains within an optimal range, preventing the transistor from entering linear operation mode and maintaining frequency stability.
2Reliability
If a bias voltage of a collector increases at low temperature, then the transistor can maintain operation, but the transistor performs linear operation and oscillation frequency varies
Solution Approach 1:
The feedback mechanism through the P-type transistor continuously monitors and regulates the collector voltage even at low temperatures. This prevents the bias voltage from increasing excessively, thereby avoiding linear operation mode and maintaining accurate oscillation frequency across temperature variations.
Solution Approach 2:
The circuit proactively counteracts the temperature-induced voltage increase by using the P-type transistor to preemptively regulate the collector voltage before it can cause linear operation. This preliminary control action prevents frequency accuracy degradation before it occurs.
3Power
If a drain voltage of the MOS transistor increases, then the transistor can operate with higher power, but the circuit operation is influenced similarly to bipolar transistor
Solution Approach 1:
The patent applies the same feedback principle to MOS transistors, connecting the drain to the gate of a P-type transistor which controls the gate of the MOS transistor. This feedback path regulates the drain voltage, preventing excessive voltage increases and maintaining stable circuit operation.
Solution Approach 2:
The P-type transistor actively controls the drain voltage parameter, preventing it from exceeding optimal levels. This parameter regulation ensures the MOS transistor operates in the correct region and maintains circuit stability despite power variations.
Data Source
AI summary
An oscillation circuit that causes a vibrator to oscillate includes a bipolar transistor for oscillation, a P-type transistor having a gate to which a collector voltage of the bipolar transistor is input and a source to which a base of the bipolar transistor is connected, a first current source that supplies a current to the bipolar transistor, and a second current source that supplies a current to the P-type transistor.