Push-Pull RF Switch Circuit for High-Linearity Low-Power Operation
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Solution Overview
Problem
PiN diode configurations in RF switch circuits can only sink, not source, large ac current swings, leading to a trade-off between linearity and dc power dissipation, particularly in high-power applications like 5G base stations.
Innovation Solution
Implementing a push-pull diode-based configuration with a first PiN diode configured to sink or source alternating current and a second diode-based device, along with an impedance inversion circuit and a bias circuit, allowing both current sourcing and sinking without requiring Class-A biasing, thereby reducing dc current dissipation while maintaining high linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a unidirectional PiN diode is used as a shunt switch in a quarter wavelength switch, then the circuit can sink large ac current swings, but it cannot source large ac current swings, requiring Class-A biasing which increases dc power dissipation
Solution Approach 1:
The single PiN diode is segmented into two separate PiN diodes (first and second PiN diodes) that operate in complementary fashion. One diode sources current while the other sinks current, allowing the circuit to handle full bidirectional current swings without requiring Class-A biasing of a single device.
Solution Approach 2:
Instead of using a single diode that must handle both sourcing and sinking, the invention inverts the approach by using two diodes where each specializes in one function. The roles are inverted between the two devices, with one sourcing and one sinking, eliminating the need for the single diode to operate in inefficient Class-A mode.
2Reliability
If Class-A biasing is applied to a shunt PiN diode to maintain high linearity, then linearity performance is improved, but dc power dissipation increases significantly
Solution Approach 1:
The single PiN diode is segmented into two PiN diodes operating in complementary fashion, allowing each to operate in more efficient biasing modes while collectively maintaining high linearity through their coordinated action.
Solution Approach 2:
The biasing parameters are changed from Class-A (continuous conduction) to a complementary switching mode where each diode operates only when needed. This parameter change reduces average current flow and associated power dissipation while maintaining signal fidelity.
3Device complexity
If a single PiN diode configuration is used, then the circuit structure is simple, but it cannot efficiently handle bidirectional current swings in high-power applications
Solution Approach 1:
The single PiN diode is segmented into two PiN diodes that operate in complementary fashion, allowing the circuit to handle full bidirectional current swings without requiring Class-A biasing of a single device.
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
The push-pull diode-based configuration enables significant reduction in dc current dissipation, achieving high linearity and efficient operation by allowing both current sourcing and sinking, thus improving the performance of RF switch circuits in high-power applications.
Implementation Method 1
A PiN diode typically behaves as a current-controlled non-linear resistor and capacitor/varactor at radio and microwave frequencies
Implementation Method 2
A PiN diode typically behaves as a current-controlled non-linear resistor and capacitor/varactor at radio and microwave frequencies
Implementation Method 3
the λ/4 transmission line transforms from a low impedance at Node 120 to a high impedance at Node B 150
Implementation Method 4
Node 120 is shorted to ac ground by the shunt switch PiN diode 132
Data Source
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AI summary
A radio frequency, RF, switch circuit (201, 301, 401, 501, 601, 701, 751, 801) includes at least one first PiN diode device (252, 352, 452, 552, 652, 752, 852, 945) configured to sink or source a first alternating current; and an impedance inversion circuit (222, 322, 422, 522, 622, 722, 822, 922), connected to the at least one first PiN diode device and arranged to provide a transformed impedance between a first side of the impedance inversion circuit and a second side of the impedance inversion circuit. The RF switch further includes a second diode-based device (254, 354, 454, 554, 654, 754, 854, 945) configured to source or sink a second alternating current; and a bias circuit (330, 430, 530, 630, 830, 930) connected to at least one of the at least one first PiN diode device and the second diode-based device, wherein the at least one first PiN diode device cooperates with the second diode-based device as a push-pull current circuit.