mm-Wave Frequency Tripler Biasing for Stable LO Power
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Solution Overview
Problem
The generation of local oscillator (LO) signals at mm-wave frequencies is limited by poor phase noise performance due to higher loss caused by passive elements and a smaller achievable frequency tuning range, making it challenging to cover the entire band effectively in communication devices.
Innovation Solution
A frequency tripler architecture with a large signal feedback-based biasing scheme is used to generate LO signals, which senses the large signal device performance and adjusts the bias voltage using feedback to maintain constant output power across process, voltage, and temperature (PVT) variations, reducing the need for manual calibration and minimizing area and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mm-wave frequency generation is used to increase bandwidth, then data rates and spectrum utilization are improved, but phase noise performance deteriorates due to higher loss from passive elements
Solution Approach 1:
The patent implements a feedback-based biasing scheme where the bias voltage to the frequency tripler is dynamically adjusted based on detected output power levels. This closed-loop control compensates for PVT variations and maintains stable LO output power across process, voltage, and temperature changes, thereby improving phase noise performance while operating at mm-wave frequencies
Solution Approach 2:
The patent changes the bias voltage parameter dynamically to optimize the frequency tripler's performance. By adjusting the bias voltage based on temperature and process conditions, the system maintains consistent output power and phase noise characteristics across varying operating conditions, resolving the contradiction between high-frequency operation and phase noise performance
2Reliability
If manual calibration is implemented to compensate for PVT variations, then output power stability is improved, but device complexity and area increase
Solution Approach 1:
The patent implements a self-adjusting biasing circuit that automatically compensates for PVT variations without requiring external manual calibration. The circuit uses feedback from the output power detection to self-regulate the bias voltage, eliminating the need for complex manual calibration procedures while maintaining stable output power across process, voltage, and temperature variations
3Reliability
If feedback-based biasing is used to maintain constant output power, then PVT robustness is improved, but power consumption increases
Solution Approach 1:
The patent implements a feedback mechanism that only activates when necessary to compensate for PVT variations. Rather than continuously adjusting the bias voltage, the system monitors output power and applies corrective bias adjustments only when deviations are detected, reducing unnecessary power consumption while maintaining PVT robustness
Data Source
AI summary
A biasing scheme for a frequency multiplication circuit, and transceiver using LO signals provided by the frequency multiplication circuit are described. A frequency doubler is cascaded with a mixer to provide a mm-wave oscillator signal. The combination provides a frequency triple that of the LO frequency supplied to the frequency doubler from a PLL. A small-sized replica of the frequency doubler is used to determine biasing of transconductance devices of the frequency doubler. A voltage output of the replica is amplified and the difference between the output and a reference voltage is supplied as feedback to the control terminal of the transconductance devices to bias the transconductance devices to near threshold. The biasing is replicated at the frequency doubler to compensate for PVT variations. A PTAT current source tied to the output of the replica regulates an average output current of the frequency multiplication circuit.