Dual Conversion Transmitter Single Local Oscillator
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Solution Overview
Problem
Tunable transmitters with dual conversion architecture face challenges due to the use of multiple local oscillators, including high material costs, phase noise degradation, and difficulties in designing filters to remove spurious signals, which complicates the integration of GaAs or SiGe semiconductor processes.
Innovation Solution
A dual conversion transmitter design utilizing a single tunable oscillator, where the first mixer upconverts an Intermediate Frequency (IF) signal, and the filtered signal is then upconverted by a second mixer using a scaled version of the oscillator signal, reducing the IF bandwidth and improving phase noise characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two or more local oscillators are used in a dual conversion transmitter, then the transmitter can achieve frequency conversion across a wide band, but the material costs increase and the device complexity increases
Solution Approach 1:
The patent applies a single local oscillator to perform multiple functions: it provides the LO signal for the first mixer and, through frequency multiplication, provides the LO signal for the second mixer. This multi-functional approach eliminates the need for separate local oscillators while maintaining the dual conversion capability across wide frequency bands.
Solution Approach 2:
The patent merges the functions of multiple local oscillators into a single oscillator combined with a frequency multiplier. Instead of having separate oscillators for different conversion stages, the invention combines them into one unified frequency source that is multiplied to generate the required frequencies for both mixers.
2Adaptability or versatility
If two or more local oscillators are used in a dual conversion transmitter, then the transmitter can operate across multiple bands, but the manufacturing cost increases
Solution Approach 1:
The single local oscillator serves multiple bands and conversion stages simultaneously. By using frequency multiplication, the same oscillator can generate different frequency requirements for different bands, eliminating the need to manufacture and assemble multiple separate oscillators, thereby reducing material costs.
Solution Approach 2:
The patent changes the frequency parameter of the local oscillator through multiplication to adapt to different frequency bands. Instead of manufacturing different oscillators for different bands, the invention keeps the oscillator fixed and changes its output frequency through the multiplier, simplifying manufacturing.
3Object-generated harmful factors
If a single filter is used to remove spurious signals, then the filter passband must be wide, but this makes it difficult or impossible to filter higher order spurious mixer outputs that are too close to the passband
Solution Approach 1:
The patent extracts and removes spurious signals at the intermediate frequency stage using a filter before the second mixing operation. By filtering at this intermediate stage rather than at the final RF output, the filter operates at a lower frequency where spurious signals are more easily separated from the desired signal, simplifying the filter design.
Solution Approach 2:
The filter is placed in the signal path before the second mixer to preemptively remove spurious signals. This preliminary filtering action prevents spurious signals from proceeding through the second mixing stage, where they would become harder to filter, thus simplifying the overall filter design requirements.
4Adaptability or versatility
If the intermediate frequency band is made as wide as the final output band, then all frequency ranges can be passed, but the filter design becomes more difficult and material costs increase
Solution Approach 1:
The patent segments the frequency conversion process into two stages: first conversion to an intermediate frequency, then second conversion to the final RF frequency. The intermediate frequency band is narrower than the final output band, allowing for simpler, more cost-effective filter design at the intermediate stage while still achieving wide overall frequency coverage through the second conversion stage.
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
This approach reduces material costs, simplifies filter design, and enhances phase noise performance by using a lower frequency oscillator with a smaller tuning range, facilitating easier integration of semiconductor processes like SiGe.
Implementation Method 1
a first mixer configured to receive a first oscillator signal; the first mixer configured to receive a communication signal from an input to the electronic device; the first mixer configured to output a converted signal based on the first oscillator signal and the communication signal
Implementation Method 2
a filter configured to remove undesired spurious signals from the converted signal and output a filtered signal
Implementation Method 3
a second mixer in communication with the filter and configured to receive the filtered signal, the second mixer configured to receive a scaled version of the first oscillator signal; the second mixer in communication with an output of the electronic device and configured to output an output signal based on the scaled version of the first oscillator signal and the filtered signal
Data Source
AI summary
The present disclosure relates to systems, devices and methods related to transmitters, and/or transceivers having a single, tunable oscillator in a dual conversion architecture. In various exemplary embodiments, this transmitter may include: a first mixer configured to receive a first oscillator signal from the single oscillator; a filter configured to band pass filter the converted signal and output a filtered signal; and a second mixer in communication with the filter, configured to receive the filtered signal. This dual conversion transmitter may be configured to receive a communication signal from an input to the transmitter and to output a converted signal based on the first oscillator signal and the communication signal. The second mixer may be configured to receive a scaled version of the first oscillator signal and to output a desired frequency output signal based on the scaled version of the first oscillator signal and the filtered signal.