Power Amplifier Cascode Bias From Output Voltage Divider
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Solution Overview
Problem
Existing RF circuit designs require a dedicated pin for generating cascode bias voltages, increasing cost, component count, and reducing flexibility due to additional on-board components and pins.
Innovation Solution
A circuit using a voltage divider coupled to a power amplifier to generate an output bias voltage, eliminating the need for a dedicated pin by utilizing internal connections and nodes within the amplifier and voltage divider.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated pin is used to generate cascode bias voltages, then the power amplifier performance is improved, but the number of on-board components and pins increases
Solution Approach 1:
The patent combines the cascode bias voltage generation function with existing power amplifier internal nodes. Specifically, the bias voltage is generated from the output node of the power amplifier through a voltage divider network, eliminating the need for a separate dedicated pin. This merging of functions reduces the overall number of pins and components while maintaining the required performance.
Solution Approach 2:
The patent makes existing nodes in the power amplifier serve multiple functions. The output node is used both for signal output and for generating the cascode bias voltage through the voltage divider. This multi-functionality approach allows the same hardware resources to serve multiple purposes, reducing the need for additional dedicated components.
2Stability of the object's composition
If a dedicated pin is used for cascode bias voltage generation, then the bias voltage is stable, but the flexibility of the system is reduced
Solution Approach 1:
By merging the bias voltage generation with the existing output node, the system maintains voltage stability through the inherent properties of the power amplifier output while simultaneously improving flexibility. The voltage divider network provides stable bias generation without requiring a dedicated pin, allowing the system to be more adaptable in its implementation.
3Power
If a dedicated pin is used to connect power amplifier supply power and on-chip matching network, then the power transfer is maximized, but the cost increases
Solution Approach 1:
The patent merges the bias voltage generation function with the existing power amplifier output stage and matching network. By using the output node and implementing a voltage divider, the system achieves the required power transfer performance without adding dedicated pins or separate bias generation circuits, thereby reducing overall system cost.
Data Source
AI summary
Embodiments disclosed herein relate to power amplifiers and topology design thereof. In an example, a circuit includes a power amplifier (PA), a voltage divider, and a bias voltage generator circuit. The PA includes a first transistor coupled to receive a first input signal, a second transistor coupled to receive a second input signal, a third transistor coupled to the first transistor and coupled to the bias voltage generator circuit, and a fourth transistor coupled to the second transistor, the bias voltage generator circuit, and the third transistor. The voltage divider includes a first resistor and a second resistor. The first resistor is coupled to the third transistor of the PA. The second resistor is coupled to the fourth transistor of the PA. The first resistor and the second resistor are coupled to each other and coupled to the bias voltage generator circuit.