PN-Diode Current-Controlled Resistor for Standard IC Integration
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Solution Overview
Problem
Current-controlled resistors using PIN diodes are difficult to implement in integrated circuits due to the need for additional process steps in standard technologies like Bipolar, CMOS, or BiCMOS, which complicates their integration.
Innovation Solution
A current-controlled resistor design utilizing PN diodes with a first and second stage, each receiving part of the current control signal, and including current mirrors to control resistance values, allowing implementation in standard bipolar or BiCMOS technologies while maintaining equivalent electric properties to PIN diode-based resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PIN diodes are used to implement current-controlled resistors, then the electric properties (conductance, linearity, noise) are satisfactory, but the device complexity and manufacturing difficulty increase due to additional process steps required for intrinsic layer formation
Solution Approach 1:
The patent replaces PIN diodes with PN diodes that replicate the essential resistive behavior. The PN diode structure copies the current-controlled resistance function without requiring the intrinsic layer, thereby simplifying the manufacturing process while maintaining the desired electric properties of conductance, linearity, and noise characteristics
Solution Approach 2:
The invention changes the diode structure parameter from PIN to PN configuration. This parameter change eliminates the need for the intrinsic layer while preserving the forward-bias resistive behavior that is essential for current-controlled resistor operation in RF attenuator applications
2Ease of operation
If PIN diodes are used in current-controlled resistors, then the resistance control function is achieved, but the ease of manufacture deteriorates due to incompatibility with standard integrated circuit processes
Solution Approach 1:
The PN diode-based circuit copies the resistance control function of PIN diodes using only standard bipolar or BiCMOS components. The circuit replicates the voltage-controlled resistance behavior through a combination of PN diodes and transistors, enabling integration into standard IC processes without requiring specialized PIN diode fabrication steps
Solution Approach 2:
The patent segments the resistance control function into multiple PN diodes and transistor components working together. This segmentation allows each component to be implemented using standard process steps, and the collective behavior achieves the desired current-controlled resistance function that would otherwise require a single complex PIN diode
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the integration of current-controlled resistors into integrated circuits with equivalent conductance, linearity, and noise characteristics to PIN diode-based resistors, facilitating their use in RF applications without the need for complex PIN diode formation processes.
Implementation Method 1
the first stage includes first and second forward biased PN diodes
Implementation Method 2
each one having a variable resistance value controlled by the bias control current
Data Source
AI summary
A current-controlled resistor comprises a first input terminal configured to receive an input signal and a second input terminal configured to receive a current control signal. The resistor comprises a first stage configured to receive the current control signal; the first stage includes first and second PN diodes having first terminals of a first type and second terminals of a second type. The first terminals of the first and second PN diodes are coupled each other and a second terminal of the first PN diode is coupled to the first input terminal. The resistor comprises a second stage configured to receive the current control signal; the second stage includes a third PN diode having first and second terminals of the first and second types, the second terminal of the third PN diode being coupled to the second terminal of the second PN diode.